WO2024070098A1 - Nickel particles and method for manufacturing nickel particles - Google Patents
Nickel particles and method for manufacturing nickel particles Download PDFInfo
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- WO2024070098A1 WO2024070098A1 PCT/JP2023/023990 JP2023023990W WO2024070098A1 WO 2024070098 A1 WO2024070098 A1 WO 2024070098A1 JP 2023023990 W JP2023023990 W JP 2023023990W WO 2024070098 A1 WO2024070098 A1 WO 2024070098A1
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- Prior art keywords
- nickel
- particles
- metal element
- less
- mass
- Prior art date
Links
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims abstract description 629
- 239000002245 particle Substances 0.000 title claims abstract description 329
- 229910052759 nickel Inorganic materials 0.000 title claims abstract description 308
- 238000000034 method Methods 0.000 title claims description 33
- 238000004519 manufacturing process Methods 0.000 title claims description 26
- 229910052751 metal Inorganic materials 0.000 claims abstract description 167
- 239000002184 metal Substances 0.000 claims abstract description 165
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 71
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims abstract description 42
- 239000010949 copper Substances 0.000 claims abstract description 40
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910052797 bismuth Inorganic materials 0.000 claims abstract description 36
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052802 copper Inorganic materials 0.000 claims abstract description 33
- 239000011733 molybdenum Substances 0.000 claims abstract description 33
- 229910052742 iron Inorganic materials 0.000 claims abstract description 30
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 30
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 claims abstract description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000004544 sputter deposition Methods 0.000 claims abstract description 10
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 6
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 6
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 6
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 6
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 6
- BFDHFSHZJLFAMC-UHFFFAOYSA-L nickel(ii) hydroxide Chemical compound [OH-].[OH-].[Ni+2] BFDHFSHZJLFAMC-UHFFFAOYSA-L 0.000 claims description 37
- 150000001875 compounds Chemical class 0.000 claims description 33
- 239000011259 mixed solution Substances 0.000 claims description 29
- 229920002873 Polyethylenimine Polymers 0.000 claims description 26
- 238000005259 measurement Methods 0.000 claims description 25
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 24
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 19
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 19
- 238000009826 distribution Methods 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 16
- 229920005862 polyol Polymers 0.000 claims description 16
- 150000003077 polyols Chemical class 0.000 claims description 16
- 230000001186 cumulative effect Effects 0.000 claims description 14
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 10
- 238000001636 atomic emission spectroscopy Methods 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 5
- 235000012239 silicon dioxide Nutrition 0.000 claims description 5
- 239000003985 ceramic capacitor Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 abstract description 23
- 239000000956 alloy Substances 0.000 abstract description 23
- 238000004458 analytical method Methods 0.000 abstract description 7
- 238000004993 emission spectroscopy Methods 0.000 abstract description 3
- 238000006243 chemical reaction Methods 0.000 abstract 1
- 238000005245 sintering Methods 0.000 description 31
- 239000006185 dispersion Substances 0.000 description 26
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 21
- 239000000203 mixture Substances 0.000 description 21
- 238000006722 reduction reaction Methods 0.000 description 18
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 15
- 239000010410 layer Substances 0.000 description 13
- 239000006228 supernatant Substances 0.000 description 11
- 239000011362 coarse particle Substances 0.000 description 10
- JHXKRIRFYBPWGE-UHFFFAOYSA-K bismuth chloride Chemical compound Cl[Bi](Cl)Cl JHXKRIRFYBPWGE-UHFFFAOYSA-K 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 239000013078 crystal Substances 0.000 description 9
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 9
- 239000010970 precious metal Substances 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 8
- 230000003746 surface roughness Effects 0.000 description 8
- 238000002441 X-ray diffraction Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 229910001152 Bi alloy Inorganic materials 0.000 description 6
- 239000008188 pellet Substances 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical class [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- JZCCFEFSEZPSOG-UHFFFAOYSA-L copper(II) sulfate pentahydrate Chemical compound O.O.O.O.O.[Cu+2].[O-]S([O-])(=O)=O JZCCFEFSEZPSOG-UHFFFAOYSA-L 0.000 description 4
- 238000011156 evaluation Methods 0.000 description 4
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 4
- 230000006911 nucleation Effects 0.000 description 4
- 238000010899 nucleation Methods 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical class [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 4
- 235000015393 sodium molybdate Nutrition 0.000 description 4
- 239000011684 sodium molybdate Substances 0.000 description 4
- TVXXNOYZHKPKGW-UHFFFAOYSA-N sodium molybdate (anhydrous) Chemical compound [Na+].[Na+].[O-][Mo]([O-])(=O)=O TVXXNOYZHKPKGW-UHFFFAOYSA-N 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 229910000881 Cu alloy Inorganic materials 0.000 description 3
- 229910000640 Fe alloy Inorganic materials 0.000 description 3
- 229910001182 Mo alloy Inorganic materials 0.000 description 3
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 239000003638 chemical reducing agent Substances 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010304 firing Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 229910001453 nickel ion Inorganic materials 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000004917 polyol method Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- PUPZLCDOIYMWBV-UHFFFAOYSA-N (+/-)-1,3-Butanediol Chemical compound CC(O)CCO PUPZLCDOIYMWBV-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000005749 Copper compound Substances 0.000 description 2
- 238000005169 Debye-Scherrer Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 150000001622 bismuth compounds Chemical class 0.000 description 2
- WERYXYBDKMZEQL-UHFFFAOYSA-N butane-1,4-diol Chemical compound OCCCCO WERYXYBDKMZEQL-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 150000001880 copper compounds Chemical class 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical class [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Chemical class 0.000 description 2
- IKDUDTNKRLTJSI-UHFFFAOYSA-N hydrazine hydrate Chemical compound O.NN IKDUDTNKRLTJSI-UHFFFAOYSA-N 0.000 description 2
- 150000002506 iron compounds Chemical class 0.000 description 2
- 239000005078 molybdenum compound Substances 0.000 description 2
- 150000002752 molybdenum compounds Chemical class 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 2
- YJVFFLUZDVXJQI-UHFFFAOYSA-L palladium(ii) acetate Chemical compound [Pd+2].CC([O-])=O.CC([O-])=O YJVFFLUZDVXJQI-UHFFFAOYSA-L 0.000 description 2
- 238000005240 physical vapour deposition Methods 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Chemical class 0.000 description 2
- CQLFBEKRDQMJLZ-UHFFFAOYSA-M silver acetate Chemical compound [Ag+].CC([O-])=O CQLFBEKRDQMJLZ-UHFFFAOYSA-M 0.000 description 2
- 229940071536 silver acetate Drugs 0.000 description 2
- 229910001961 silver nitrate Inorganic materials 0.000 description 2
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 239000012756 surface treatment agent Substances 0.000 description 2
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- JJLJMEJHUUYSSY-UHFFFAOYSA-L Copper hydroxide Chemical compound [OH-].[OH-].[Cu+2] JJLJMEJHUUYSSY-UHFFFAOYSA-L 0.000 description 1
- 239000005750 Copper hydroxide Substances 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- ALQSHHUCVQOPAS-UHFFFAOYSA-N Pentane-1,5-diol Chemical compound OCCCCCO ALQSHHUCVQOPAS-UHFFFAOYSA-N 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical class [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 102100025490 Slit homolog 1 protein Human genes 0.000 description 1
- 101710123186 Slit homolog 1 protein Proteins 0.000 description 1
- 102100027340 Slit homolog 2 protein Human genes 0.000 description 1
- 101710133576 Slit homolog 2 protein Proteins 0.000 description 1
- 229910001128 Sn alloy Inorganic materials 0.000 description 1
- UWHCKJMYHZGTIT-UHFFFAOYSA-N Tetraethylene glycol, Natural products OCCOCCOCCOCCO UWHCKJMYHZGTIT-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- WUOACPNHFRMFPN-UHFFFAOYSA-N alpha-terpineol Chemical compound CC1=CCC(C(C)(C)O)CC1 WUOACPNHFRMFPN-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 1
- 235000018660 ammonium molybdate Nutrition 0.000 description 1
- 239000011609 ammonium molybdate Substances 0.000 description 1
- 229940010552 ammonium molybdate Drugs 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229940036348 bismuth carbonate Drugs 0.000 description 1
- 229940049676 bismuth hydroxide Drugs 0.000 description 1
- 229910000416 bismuth oxide Inorganic materials 0.000 description 1
- 229940036359 bismuth oxide Drugs 0.000 description 1
- TZSXPYWRDWEXHG-UHFFFAOYSA-K bismuth;trihydroxide Chemical compound [OH-].[OH-].[OH-].[Bi+3] TZSXPYWRDWEXHG-UHFFFAOYSA-K 0.000 description 1
- FBXVOTBTGXARNA-UHFFFAOYSA-N bismuth;trinitrate;pentahydrate Chemical compound O.O.O.O.O.[Bi+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FBXVOTBTGXARNA-UHFFFAOYSA-N 0.000 description 1
- BMRWNKZVCUKKSR-UHFFFAOYSA-N butane-1,2-diol Chemical compound CCC(O)CO BMRWNKZVCUKKSR-UHFFFAOYSA-N 0.000 description 1
- OWBTYPJTUOEWEK-UHFFFAOYSA-N butane-2,3-diol Chemical compound CC(O)C(C)O OWBTYPJTUOEWEK-UHFFFAOYSA-N 0.000 description 1
- BIOOACNPATUQFW-UHFFFAOYSA-N calcium;dioxido(dioxo)molybdenum Chemical compound [Ca+2].[O-][Mo]([O-])(=O)=O BIOOACNPATUQFW-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000013626 chemical specie Substances 0.000 description 1
- 229910001956 copper hydroxide Inorganic materials 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(I) oxide Inorganic materials [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 description 1
- NWFNSTOSIVLCJA-UHFFFAOYSA-L copper;diacetate;hydrate Chemical compound O.[Cu+2].CC([O-])=O.CC([O-])=O NWFNSTOSIVLCJA-UHFFFAOYSA-L 0.000 description 1
- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- KRFJLUBVMFXRPN-UHFFFAOYSA-N cuprous oxide Chemical compound [O-2].[Cu+].[Cu+] KRFJLUBVMFXRPN-UHFFFAOYSA-N 0.000 description 1
- 229940112669 cuprous oxide Drugs 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- SQIFACVGCPWBQZ-UHFFFAOYSA-N delta-terpineol Natural products CC(C)(O)C1CCC(=C)CC1 SQIFACVGCPWBQZ-UHFFFAOYSA-N 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- TYIXMATWDRGMPF-UHFFFAOYSA-N dibismuth;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Bi+3].[Bi+3] TYIXMATWDRGMPF-UHFFFAOYSA-N 0.000 description 1
- GMZOPRQQINFLPQ-UHFFFAOYSA-H dibismuth;tricarbonate Chemical compound [Bi+3].[Bi+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O GMZOPRQQINFLPQ-UHFFFAOYSA-H 0.000 description 1
- SZXQTJUDPRGNJN-UHFFFAOYSA-N dipropylene glycol Chemical compound OCCCOCCCO SZXQTJUDPRGNJN-UHFFFAOYSA-N 0.000 description 1
- SFXJSNATBHJIDS-UHFFFAOYSA-N disodium;dioxido(oxo)tin;trihydrate Chemical compound O.O.O.[Na+].[Na+].[O-][Sn]([O-])=O SFXJSNATBHJIDS-UHFFFAOYSA-N 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- RXPAJWPEYBDXOG-UHFFFAOYSA-N hydron;methyl 4-methoxypyridine-2-carboxylate;chloride Chemical compound Cl.COC(=O)C1=CC(OC)=CC=N1 RXPAJWPEYBDXOG-UHFFFAOYSA-N 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 235000014413 iron hydroxide Nutrition 0.000 description 1
- QZRHHEURPZONJU-UHFFFAOYSA-N iron(2+) dinitrate nonahydrate Chemical compound O.O.O.O.O.O.O.O.O.[Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O QZRHHEURPZONJU-UHFFFAOYSA-N 0.000 description 1
- WOSISLOTWLGNKT-UHFFFAOYSA-L iron(2+);dichloride;hexahydrate Chemical compound O.O.O.O.O.O.Cl[Fe]Cl WOSISLOTWLGNKT-UHFFFAOYSA-L 0.000 description 1
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 229910001092 metal group alloy Inorganic materials 0.000 description 1
- 229910000476 molybdenum oxide Inorganic materials 0.000 description 1
- DNIAPMSPPWPWGF-UHFFFAOYSA-N monopropylene glycol Natural products CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- PQQKPALAQIIWST-UHFFFAOYSA-N oxomolybdenum Chemical compound [Mo]=O PQQKPALAQIIWST-UHFFFAOYSA-N 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920003196 poly(1,3-dioxolane) Polymers 0.000 description 1
- 229920001601 polyetherimide Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 235000013772 propylene glycol Nutrition 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 229910001923 silver oxide Inorganic materials 0.000 description 1
- YPNVIBVEFVRZPJ-UHFFFAOYSA-L silver sulfate Chemical compound [Ag+].[Ag+].[O-]S([O-])(=O)=O YPNVIBVEFVRZPJ-UHFFFAOYSA-L 0.000 description 1
- 229910000367 silver sulfate Inorganic materials 0.000 description 1
- LMEWRZSPCQHBOB-UHFFFAOYSA-M silver;2-hydroxypropanoate Chemical compound [Ag+].CC(O)C([O-])=O LMEWRZSPCQHBOB-UHFFFAOYSA-M 0.000 description 1
- MQHGEVXQSFWXCE-UHFFFAOYSA-M silver;cyclohexanecarboxylate Chemical compound [Ag+].[O-]C(=O)C1CCCCC1 MQHGEVXQSFWXCE-UHFFFAOYSA-M 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010421 standard material Substances 0.000 description 1
- 230000007847 structural defect Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000004441 surface measurement Methods 0.000 description 1
- 229940116411 terpineol Drugs 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical compound OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
Definitions
- the present invention relates to nickel particles and a method for producing the same.
- Nickel particles are generally used to form the internal electrodes of multilayer ceramic capacitors (hereafter referred to as "MLCCs") used in electronic devices.
- MLCCs multilayer ceramic capacitors
- defects can occur in the internal electrodes due to differences in the sintering temperatures of the raw materials.
- Patent Document 1 discloses a technology in which nickel powder containing tin or bismuth obtained by the PVD or CVD method is used to form the internal electrodes of an MLCC.
- the document states that adding a non-magnetic metal such as tin to nickel powder distorts the crystal structure of the nickel, thereby increasing the sintering temperature of the nickel powder.
- Patent Document 2 discloses a technique for using nickel powder, which has a roughly spherical particle shape and is surface-treated with tin, to form the internal electrodes of an MLCC. The same document also discloses that surface treatment is performed using bismuth in addition to tin. The same document also describes that the sintering behavior is improved by using the nickel powder described in the document.
- an object of the present invention is to provide nickel particles that have high sintering resistance without excessively increasing electrical resistance.
- the present invention relates to a nickel particle having a surface region comprising an alloy of nickel and a metallic element M,
- the metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
- the content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
- a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy
- the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%)
- the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %)
- the present invention provides nickel particles having a value of X/Y of
- the present invention also provides a method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of: Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine, The heating reduces the nickel hydroxide particles to nickel base particles,
- a method for producing nickel particles comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
- the metal element M is at least one element selected from the group consisting of bismuth, copper, iron and molybdenum.
- the nickel particles of the present invention have a nickel base particle and a surface region containing an alloy of nickel and metal element M (hereinafter also referred to as “nickel-metal M alloy") located on the surface of the base particle.
- nickel base particle refers to a particle that is substantially composed of nickel element, with the remainder containing unavoidable elements.
- unavoidable elements include oxygen element and carbon element derived from oxygen and carbon dioxide in the air, and nitrogen element that may be mixed in during the manufacturing process of the nickel particles.
- nickel-metal M alloy refers to a nickel-based alloy containing the metal element M described below.
- the nickel-metal M alloy is substantially composed of an alloy of nickel element and metal element M, and contains inevitable elements as the remainder.
- the metal element M may be present in part in the state of the metal element M alone (i.e., in the state of metal).
- the metal element M may be present in part in the state of a compound of the metal element M.
- the metal element M may be present in a state of a combination of two or more of these.
- the metal element M When the metal element M is present in the surface region containing the nickel-metal M alloy in the state of a compound of the metal element M, examples of the compound include, but are not limited to, oxides, hydroxides, sulfides, sulfates, borides, phosphides, etc. containing the metal M. However, it is desirable that the metal element M in the surface region containing the nickel-metal M alloy is substantially composed of only an alloy with nickel, from the viewpoint of maximizing the inherent advantages of the nickel particles of the present invention.
- the metal element M in the nickel particles is preferably at least one selected from bismuth, copper, iron and molybdenum.
- the metal element M is bismuth, copper, iron or molybdenum, the sintering resistance of the nickel particles can be further improved without excessively increasing the electrical resistance of the nickel particles.
- the metal element M may be only one of bismuth, copper, iron and molybdenum, or any combination of two or more of them. In the following description, when the metal element M (or metal M) is mentioned, it means bismuth, copper, iron or molybdenum, or any combination of two or more of them, depending on the context.
- the nickel particles contain nickel-metal M alloy in their surface region can be confirmed by the following method. Specifically, first, it is confirmed by X-ray photoelectron spectroscopy (hereinafter also referred to as "XPS") that the nickel particles contain the metal element M in their surface region and that the metal element M is mainly in a metallic state. Next, it is confirmed that the a-axis length in the X-ray diffraction peak of the nickel particles is longer than the a-axis length in the X-ray diffraction peak obtained by measuring only the nickel particles in advance. The extension of the a-axis length in the X-ray diffraction peak means that the substance is in a solid solution.
- XPS X-ray photoelectron spectroscopy
- the metal element M confirmed by the XPS measurement exists in a metallic state in the surface region of the nickel particles, and the metal element M and nickel are in a solid solution confirmed by comparing the a-axis lengths, it can be confirmed that the nickel particles contain a nickel-metal M alloy in their surface region.
- the proportion of the metal element M in the surface region of the nickel particles can be measured by XPS.
- this region is also referred to as the "particle surface region"
- the value of X which is the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is 0.5 at% or more in the particle surface region.
- the "maximum value” refers to the maximum value of the value of X when multiple values of X measured along the thickness direction of the particle surface region are different.
- the metal element M exists so as to have a portion where the value of X is 0.5 at% or more from the viewpoint of further increasing the sintering resistance of the nickel particles described later.
- the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 3 at% or more, even more preferably 7 at% or more, and particularly preferably 14 at% or more.
- the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 15 at% or less.
- the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, even more preferably 8 at% or more, and particularly preferably 12 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 20 at% or less, and even more preferably 14 at% or less.
- the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 7 at% or more.
- the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 9 at% or less.
- the value of X (at%) is more preferably 1 at% or more, further preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 8 at% or more.
- the value of X (at%) is more preferably 70 at% or less, further preferably 35 at% or less, even more preferably 30 at% or less, and even more preferably 10 at% or less.
- outermost surface of nickel particles refers to the outermost surface of nickel particles containing a surface treatment agent such as an organic acid or amine when the surface of the nickel particles is present.
- a surface treatment agent such as an organic acid or amine
- the nickel particles preferably contain 0.09% by mass or more and 15.8% by mass or less of the metal element M relative to the entire nickel particles.
- the content of the metal element M relative to the nickel particles is within this range, the sintering resistance can be further improved without excessively increasing the electrical resistance of the nickel particles.
- the metal element M is bismuth, from the same viewpoint as above, the content of the bismuth element relative to the entire nickel particle is more preferably 0.3 mass% or more, even more preferably 0.4 mass% or more, even more preferably 1 mass% or more, and even more preferably 6.7 mass% or more.
- the content of the bismuth element relative to the entire nickel particle is more preferably 15.8 mass% or less, even more preferably 13 mass% or less, even more preferably 11.4 mass% or less, and even more preferably 10 mass% or less.
- the metal element M is copper
- the content of copper element with respect to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 2.1 mass% or more, and even more preferably 4.3 mass% or more.
- the content of copper element with respect to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 7.6 mass% or less, even more preferably 6.5 mass% or less, even more preferably 6 mass% or less, and particularly preferably 5.4 mass% or less.
- the metal element M is iron
- the content of the iron element relative to the entire nickel particle is more preferably 0.09% by mass or more, even more preferably 0.28% by mass or more, even more preferably 0.40% by mass or more, and even more preferably 0.47% by mass or more.
- the content of the iron element relative to the entire nickel particle is more preferably 11.4% by mass or less, even more preferably 6% by mass or less, even more preferably 2.87% by mass or less, even more preferably 1.91% by mass or less, and particularly preferably 0.96% by mass or less.
- the metal element M is molybdenum
- the molybdenum element content relative to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 1.1 mass% or more, and even more preferably 1.6 mass% or more.
- the molybdenum element content relative to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 6.4 mass% or less, even more preferably 6 mass% or less, even more preferably 4.9 mass% or less, and particularly preferably 3.3 mass% or less.
- the content of the metal element M relative to the entire nickel particles can be measured by ICP emission spectrometry, which will be described later.
- the content of the metal element M in the entire nickel particle satisfies the above-mentioned range, and the value of Y (at%), which is the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is preferably 0.1 at% or more and 7 at% or less in the entire nickel particle. It is preferable that the metal element M is present so that the value of Y is within this range, from the viewpoint of further increasing the sintering resistance without excessively increasing the electrical resistance of the nickel particle.
- the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, and particularly preferably 2 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 5 at% or less, even more preferably 4 at% or less, and even more preferably 3 at% or less.
- the value of Y is more preferably 0.2 at% or more, even more preferably 0.5 at% or more, even more preferably 1 at% or more, even more preferably 2 at% or more, and particularly preferably 4 at% or more. Also, the value of Y is more preferably 7 at% or less, even more preferably 6 at% or less, and even more preferably 5 at% or less.
- the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, and even more preferably 0.5 at% or more.
- the value of Y is more preferably 6 at% or less, even more preferably 3 at% or less, even more preferably 2 at% or less, and even more preferably 1 at% or less.
- the value of Y is more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, even more preferably 0.7 at% or more, and particularly preferably 1 at% or more.
- the value of Y is more preferably 6 at% or less, even more preferably 4 at% or less, even more preferably 3 at% or less, and even more preferably 2 at% or less.
- the value of Y which is the ratio of the number of atoms of the metal element M contained in the entire nickel particle, is measured by ICP atomic emission spectroscopy. Specifically, first, the entire nickel particle is measured by ICP atomic emission spectroscopy to determine the content ratio of the nickel element and the content ratio of the metal element M. Next, the content ratio of the nickel element (mass%) is divided by the atomic weight of the nickel element (58.7) to convert the content ratio to the atomic number A Ni of the nickel element.
- the content ratio of the metal element M (mass%) is divided by the atomic weight of the metal element M (bismuth is 209, copper is 63.6, iron is 55.9, and molybdenum is 96) to convert the content ratio to the atomic number A M of the metal element M. Then, the ratio of the number of atoms of the metal element M to the atomic number A Ni of the nickel element and the atomic number A M of the metal element M (A M / (A Ni +A M ) ⁇ 100) is calculated to obtain the value of Y.
- the relationship between the value of X and the value of Y affects the sintering resistance of nickel particles.
- the temperature at which the nickel particles start to shrink due to sintering increases, that is, the sintering resistance increases.
- the temperature at which the internal electrodes shrink due to sintering of the nickel particles in the firing process which is one of the manufacturing processes, can be made as close as possible to the temperature at which the dielectric layer shrinks due to sintering of the dielectric particles.
- Reducing the difference in temperature at which the internal electrodes and the dielectric layer shrink is advantageous because the time at which the internal electrodes and the dielectric layer shrink overlap during the temperature rise process in the firing process. Specifically, it is advantageous from the viewpoint of effectively preventing the occurrence of structural defects such as cracks and delamination (interlayer peeling at the interface between the internal electrodes and the dielectric layers) caused by the difference in temperature and shrinkage rate at which the internal electrodes and the dielectric layers shrink in the firing process of the MLCC.
- the value of X/Y in the nickel particles is more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 4 or more, even more preferably 5 or more, and particularly preferably 7 or more.
- the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, and even more preferably 20 or less.
- the value of X/Y in the nickel particles is more preferably 0.5 or more, even more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more.
- the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, particularly preferably 7 or less, and especially preferably 3 or less.
- the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 5 or more, and particularly preferably 10 or more.
- the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of making the above-mentioned advantages more prominent.
- the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3 or more, even more preferably 3.7 or more, and particularly preferably 5 or more.
- the value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, and particularly preferably 7 or less.
- the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M may be constant in the depth direction or may vary.
- the value of the ratio may decrease continuously or stepwise from the surface of the nickel particle toward the center.
- the value of the ratio gradually decreases from the outermost surface to a sputtering depth of 20 nm, since this further improves the sintering resistance of the nickel particle.
- the value of X/X1 is 0.1 or more and 15 or less in terms of further improving the sintering resistance of the nickel particle.
- the value of X/X1 is more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more.
- the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 4 or less, particularly preferably 3 or less, and especially preferably 2.5 or less.
- the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more.
- the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
- the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 2 or less. When the metal element M is molybdenum, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 1 or more, and even more preferably 2 or more.
- the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
- the method for measuring X1 will be explained in the Examples below.
- the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1.7 or more, particularly preferably 2 or more, and especially preferably 5 or more.
- the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 7 or less.
- the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 3 or more, and even more particularly preferably 5 or more.
- the value of X1 itself is more preferably 20 or less, even more preferably 15 or less, and even more preferably 10 or less.
- the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 2 or more, and even more particularly preferably 4 or more.
- the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 6 or less.
- the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, especially preferably 2 or more, and especially especially preferably 4 or more.
- the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, even more preferably 6 or less, and even more preferably 5 or less.
- the nickel particles of the present invention preferably have a value of D50 , which is the number-cumulative particle diameter at 50% of the cumulative number, of 20 nm or more and 200 nm or less.
- D50 is the number-cumulative particle diameter at 50% of the cumulative number, of 20 nm or more and 200 nm or less.
- the nickel particles of the present invention are preferably fine particles.
- the nickel particles of the present invention have a particle diameter D50 within this range, there is an advantage that when the nickel particles of the present invention are used in various applications, for example, as internal electrodes of MLCCs, short circuits between the internal electrodes are less likely to occur.
- the particle diameter D50 of the nickel particles is more preferably 20 nm or more and 150 nm or less, even more preferably 40 nm or more and 150 nm or less, and even more preferably 40 nm or more and 100 nm or less.
- the particle diameter D50 of the nickel particles is measured by observing the nickel particles with a scanning electron microscope (SEM). In detail, the nickel particles are photographed with a SEM at a magnification of 50,000 times, and the area of the photographed nickel particles is calculated. The circle equivalent diameter is calculated from the area. The particle size distribution is calculated based on the calculated circle equivalent diameter.
- the particle size distribution is plotted on the horizontal axis of the graph representing the equivalent circle diameter and on the vertical axis representing the number frequency.
- the number-cumulative particle size at 50% by number of cumulative particles is defined as D50 .
- the circle equivalent diameter is determined for 5,000 or more nickel particles.
- the circle equivalent diameter is calculated using image analysis particle size distribution measurement software (Mac-View, manufactured by Mountec Co., Ltd.).
- the smallest unit of nickel particle to be observed is determined by whether or not a particle interface that can be recognized as an independent particle is observed using SEM. Therefore, even if an agglomerate consisting of multiple particles is observed, if a particle interface is observed in the agglomerate, the area defined by the particle interface is recognized as a single particle.
- the nickel particles of the present invention preferably have a small proportion of coarse particles.
- the proportion of particles having a particle size of 1.5 times or more of D50 (hereinafter also referred to as "coarse particle proportion") is preferably 0.5% by number or less, more preferably 0.3% by number or less, and even more preferably 0.1% by number or less.
- the nickel particles of the present invention are preferably fine particles, have a low proportion of coarse particles, and have a particle size as uniform as possible. In other words, it is preferable that the particle size distribution curve is sharp.
- the sharpness of the particle size distribution curve can be evaluated by the coefficient of variation of the particle size.
- the coefficient of variation is a value defined as ( ⁇ /D 50 ) ⁇ 100(%), where ⁇ (nm) is the standard deviation of the particle size in the particle size distribution.
- the value of the coefficient of variation is preferably 14% or less, from the viewpoint of reducing the surface roughness of the conductive film formed from the nickel particles.
- the coefficient of variation is more preferably 13% or less, and even more preferably 12% or less.
- a coefficient of variation as low as about 8% can reduce the surface roughness of the conductive film to a sufficiently satisfactory degree.
- the nickel particles of the present invention preferably have high nickel crystallinity.
- High nickel crystallinity means that the temperature at which the nickel particles of the present invention begin to shrink due to sintering increases.
- high nickel crystallinity means that the nickel particles have high sintering resistance, as described above.
- the crystallinity of nickel is often evaluated by Cs/D 50 , which is the ratio of the crystallite size Cs (nm) to the particle size D 50 (nm). The larger the Cs/D 50 value, the higher the crystallinity of the nickel can be evaluated.
- the Cs/D 50 value is preferably 0.3 or more, more preferably 0.34 or more, and even more preferably 0.37 or more.
- the larger the Cs/D 50 value the higher the temperature at which nickel particles begin to sinter and shrink.
- the Cs/D 50 value is preferably 0.6 or less, the temperature can be made sufficiently high, and from this viewpoint, the Cs/D 50 value is more preferably 0.55 or less, and even more preferably 0.52 or less.
- the value of the crystallite size Cs itself is preferably 15 nm or more and 70 nm or less, more preferably 18 nm or more and 70 nm or less, and even more preferably 20 nm or more and 70 nm or less, from the viewpoint of sufficiently raising the temperature at which the nickel particles sinter and begin to shrink.
- the crystallite size in this specification refers to the value measured by the WPPF (whole powder pattern fitting) method.
- WPPF whole powder pattern fitting
- the Scherrer method is also known as a method for measuring crystallite size, and when the degree of distortion of the crystal is large, the value of the crystallite size obtained based on the Scherrer method is unreliable, so the WPPF method, which is less likely to cause such a problem, is adopted in the present invention. Details of the method for measuring the nickel crystallite size based on the WPPF method will be described in the Examples below.
- the nickel particles of the present invention preferably do not excessively increase electrical resistance.
- the performance of the MLCC can be further improved. Therefore, in order to prevent excessive increase in electrical resistance, it is preferable to control the crystal structure of the nickel particles so that the pure nickel component is increased in the nickel particles having a surface region containing nickel-metal M alloy.
- the a-axis length of the crystal lattice in the nickel crystal structure is preferably 3.520 ⁇ or more and 3.529 ⁇ or less, more preferably 3.522 ⁇ or more and 3.526 ⁇ or less, even more preferably 3.523 ⁇ or more and 3.526 ⁇ or less, and even more preferably 3.524 ⁇ or more and 3.526 ⁇ or less.
- the a-axis length of the crystal lattice in the crystal structure of nickel particles can be measured by an X-ray diffraction device using CuK ⁇ 1 radiation, as described in the Examples below.
- the length is determined by the WPPF method, as described in the Examples below.
- the crystallite size and a-axis length of the crystal lattice in the nickel crystal structure of the present invention can be achieved, for example, by adjusting the proportion of metal element M contained in the surface region of the nickel particles, or by reducing the thickness of the surface region of the nickel particles that contains the nickel-metal M alloy. In addition, or instead, they can also be achieved by appropriately adjusting the conditions in the manufacturing method of nickel particles described below.
- the degree of sintering resistance of the nickel particles of the present invention can be evaluated by subjecting the nickel particles to thermomechanical analysis (TMA).
- TMA thermomechanical analysis
- the temperature at which the TMA shrinkage rate (%) based on room temperature (25°C) is 5% is defined as the shrinkage start temperature.
- the temperature it is preferable for the temperature to be 400°C or higher. From the viewpoint of making this advantage more prominent, it is more preferable for the temperature to be 450°C or higher, even more preferable for the temperature to be 500°C or higher, even more preferable for the temperature to be 550°C or higher, and even more preferable for the temperature to be 570°C or higher.
- nickel particles are produced by the so-called polyol method.
- the polyol method is a method in which a polyol is used as a solvent that also serves as a reducing agent.
- nickel chemical species are present in a polyol and heating is performed to cause a reduction reaction to the nickel base particles, and before the reduction reaction is completed, a compound of metal element M is mixed and further heating is performed to cause a reduction reaction to metal M, forming a surface region containing a nickel-metal M alloy on the nickel base particles.
- nickel hydroxide As the nickel species for producing nickel particles, from the viewpoint of successfully obtaining the desired nickel particles.
- Nickel hydroxide is added to a mixture containing polyol, polyvinylpyrrolidone (hereinafter also referred to as "PVP"), and polyethyleneimine (hereinafter also referred to as "PEI"). From the viewpoint of ease of handling, it is preferable to use nickel hydroxide in a particulate form.
- the polyol contained in the mixed liquid is used as a solvent and also as a reducing agent for nickel hydroxide.
- the polyol that can be used include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and polyethylene glycol.
- These polyols can be used alone or in combination of two or more.
- ethylene glycol is preferred because it has a high reducing performance due to a large proportion of hydroxyl groups relative to the molecular weight, and is liquid at room temperature and therefore easy to handle.
- the concentration of polyol in the mixed solution in the range of 50% by mass or more and 99.8% by mass or less.
- PVP is used as a dispersant for nickel hydroxide.
- PVP is preferable because it has a significant effect as a dispersant and can sharpen the particle size distribution of nickel particles generated by reduction.
- the molecular weight of these PVPs can be appropriately adjusted depending on the degree of water solubility and dispersing ability.
- the amount of PVP in the mixed solution is preferably 0.01 to 30 parts by mass per 100 parts by mass of nickel hydroxide converted into nickel. By setting it in this range, the dispersing effect can be fully expressed without excessively increasing the viscosity of the mixed solution.
- PEI acts to reduce the number of nickel ions in the mixed solution while nickel nuclei are being generated in the mixed solution, preventing nucleation and nucleus growth from proceeding simultaneously. This is because (a) PEI has unshared electron pairs that interact with nickel ions and can form coordinate bonds with nickel ions, (b) PEI has a large amount of the unshared electron pairs, and (c) PEI has hydrogen bonding sites that can interact with the surface of nickel hydroxide that is present in an undissolved state in the mixed solution.
- PEI polystyrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-sulftyrene, polystyrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-styrene-s
- this manufacturing method by setting the ratio of PVP and PEI contained in the mixed solution within a specific range, it is possible to ensure that nickel nucleation and nucleus growth occur sequentially.
- the amount of PEI in the mixture is set appropriately according to the amount of PVP, provided that the ratio of PVP to PEI satisfies the above-mentioned range.
- the mixture can also contain a precious metal catalyst.
- a precious metal catalyst for example, a precious metal compound such as a water-soluble salt of the precious metal can be used.
- water-soluble salts of precious metals include water-soluble salts of palladium, silver, platinum, gold, etc.
- palladium for example, palladium chloride, palladium nitrate, palladium acetate, ammonium palladium chloride, etc. can be used.
- the precious metal catalyst can be added in the form of the above-mentioned compound or in the form of an aqueous solution in which the compound is dissolved in water.
- the amount of precious metal catalyst contained in the mixed solution is preferably 0.01 to 5 parts by mass, particularly 0.01 to 1 part by mass, per 100 parts by mass of nickel hydroxide converted to nickel.
- the mixture containing the above components is heated with stirring to reduce the nickel hydroxide.
- the heating temperature depends on the type of polyol used, but by heating at atmospheric pressure at a temperature preferably between 150°C and 200°C, more preferably between 170°C and 200°C, and even more preferably between 190°C and 200°C, the nickel hydroxide can be successfully reduced to nickel mother particles.
- a compound of metal element M is mixed into the mixed solution.
- the compound of metal element M is mixed into the mixed solution while some nickel hydroxide remains.
- "before the reduction reaction of nickel hydroxide is completed" refers to before 80 mol % or more of the charged amount of nickel hydroxide is reduced.
- the metal element M is bismuth
- the metal element M is bismuth
- the metal element M is copper, from the same viewpoint as above, it is preferable to use, as the compound, at least one selected from the group consisting of copper nitrate trihydrate, copper sulfate pentahydrate, copper acetate monohydrate, copper hydroxide, cuprous oxide, and copper oxide, and it is particularly preferable to use copper sulfate pentahydrate.
- the metal element M is iron, from the same viewpoint as above, it is preferable to use as the compound at least one selected from the group consisting of iron nitrate nonahydrate, iron chloride hexahydrate, iron sulfate heptahydrate, iron hydroxide, and iron oxide, and it is particularly preferable to use iron sulfate heptahydrate.
- the metal element M is molybdenum
- the amount of the bismuth compound in the mixed solution, converted into bismuth is preferably 0.003 parts by mass or more per part by mass of nickel in the feed, more preferably 0.004 parts by mass or more, even more preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, per part by mass of nickel in the feed.
- the amount of the bismuth compound in the mixed solution, converted into bismuth is preferably 0.20 parts by mass or less per part by mass of nickel in the feed, more preferably 0.16 parts by mass or less, even more preferably 0.13 parts by mass or less, and even more preferably 0.12 parts by mass or less, per part by mass of nickel in the feed.
- the amount of the copper compound in the mixed solution, converted into copper is preferably 0.004 parts by mass or more per part by mass of nickel in the feed, more preferably 0.01 parts by mass or more, even more preferably 0.022 parts by mass or more, and even more preferably 0.045 parts by mass or more, per part by mass of nickel in the feed.
- the amount of the copper compound in the mixed solution, converted into copper is preferably 0.12 parts by mass or less per part by mass of nickel in the feed, more preferably 0.082 parts by mass or less, even more preferably 0.07 parts by mass or less, and even more preferably 0.06 parts by mass or less, per part by mass of nickel in the feed.
- the amount of iron compounds in the mixed solution, converted into iron is preferably 0.0009 parts by mass or more per part by mass of nickel in the feed, more preferably 0.0028 parts by mass or more, even more preferably 0.004 parts by mass or more, and even more preferably 0.0047 parts by mass or more, per part by mass of nickel in the feed.
- the amount of iron compounds in the mixed solution, converted into iron is preferably 0.12 parts by mass or less per part by mass of nickel in the feed, more preferably 0.08 parts by mass or less, even more preferably 0.06 parts by mass or less, even more preferably 0.030 parts by mass or less, and even more preferably 0.020 parts by mass or less, per part by mass of nickel in the feed.
- the amount of the molybdenum compound in the mixed solution, converted into molybdenum is preferably 0.004 parts by mass or more per part by mass of nickel charged, more preferably 0.01 parts by mass or more, even more preferably 0.013 parts by mass or more, and even more preferably 0.016 parts by mass or more, per part by mass of nickel charged.
- the amount of the molybdenum compound in the mixed solution, converted into molybdenum is preferably 0.12 parts by mass or less per part by mass of nickel charged, more preferably 0.07 parts by mass or less, even more preferably 0.06 parts by mass or less, even more preferably 0.051 parts by mass or less, and even more preferably 0.034 parts by mass or less, per part by mass of nickel charged.
- the mixed solution containing the compound of the metal element M is heated while being stirred to reduce the nickel hydroxide and the compound in the mixed solution.
- This reduction reaction reduces the nickel hydroxide remaining in the mixed solution to nickel, and if the metal element M is bismuth, the compound of the metal element M is reduced to bismuth.
- the metal element M is copper, the compound of the metal element M is reduced to copper.
- the metal element M is iron, the compound of the metal element M is reduced to iron.
- the metal element M is molybdenum, the compound of the metal element M is reduced to molybdenum.
- the nickel hydroxide and the compound of the metal element M are simultaneously reduced, and a surface region containing a nickel-metal M alloy in which the nickel element and the metal M are homogeneously dissolved in solid solution is formed on the surface of the nickel mother particle.
- a part of the metal element M exists in the state of the simple substance of the metal element M, in the state of a compound of the metal element M, or in a state in which two or more of these are combined.
- the heating temperature of the mixture depends on the type of polyol and metal element M compound used, but is preferably 150°C to 200°C under atmospheric pressure, more preferably 170°C to 200°C, and even more preferably 190°C to 200°C. By keeping the heating temperature within this range, nickel hydroxide and the metal element M compound can be reduced simultaneously, and a surface region containing nickel-metal M alloy can be successfully formed on the surface of the nickel mother particles.
- the polyol in the resulting dispersion of nickel particles is replaced with water, and then the replaced water is replaced again with methanol to wash the nickel particles, followed by vacuum drying. In this manner, the nickel particles of the present invention can be produced.
- a PVD method or CVD method can be performed by adding a raw material of metal element M to a nickel raw material.
- a nickel-metal M alloy is formed throughout the nickel particles.
- the content of metal element M, bismuth, copper, iron and/or molybdenum, in the entire nickel particle becomes excessively high, resulting in a problem of high electrical resistance.
- the particle size of the nickel particles becomes uneven, and when a conductive film is formed using the nickel particles, the surface of the conductive film becomes rough, which is one of the causes of short circuits between the internal electrodes of the MLCC.
- the metal element M when iron and/or molybdenum are used as the metal element M, a layer containing iron oxide and/or molybdenum oxide is formed on the surface of the nickel particles due to the fact that simple iron and molybdenum are easily oxidized.
- nickel particles with such a layer are sintered during the manufacture of MLCC, the oxide contained in the layer is absorbed into the dielectric layer, and the sintering resistance of the nickel particles is not high.
- the nickel particles of the present invention which are made of nickel mother particles and a nickel-metal M alloy arranged on the surface thereof, can increase the sintering resistance without excessively increasing the electrical resistance.
- the surface of the conductive film can be made smooth. For these reasons, as described above, it is preferable to produce nickel particles by simultaneously reducing the nickel hydroxide and the compound of the metal element M while some of the nickel hydroxide remains.
- the nickel particles produced by the above method are used in a variety of fields, taking advantage of the fact that they have a fine, uniform particle size and a surface region containing nickel-metal M alloy on the surface of the nickel particles. They are particularly suitable for use in forming the internal electrodes of MLCCs.
- the metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
- the content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
- the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at%)
- Coefficient of variation (%) ( ⁇ /D 50 ) ⁇ 100
- the value of Cs/ D50 is 0.3 or more and 0.6 or less.
- Nickel particles according to any one of [1] to [3].
- a method for producing nickel particles comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles, The method for producing nickel particles, wherein the metal element M is at least one selected from bismuth, copper, iron and molybdenum.
- Example 1 A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 12 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker.
- the polyethyleneimine was branched and had a number average molecular weight of 1800.
- the mixture was heated while stirring, and a reduction reaction was carried out at 198 ° C. under atmospheric pressure for 5 hours. At this point, the reduction of nickel hydroxide had progressed to 80 mol % with respect to the amount of nickel hydroxide charged.
- the supernatant of the dispersion was removed.
- the series of operations was repeated five times.
- 50 g of methanol was added and the dispersion was stirred for 10 minutes.
- the supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain nickel particles.
- Example 2 The amount of the aqueous palladium nitrate solution and the amount of bismuth chloride added, as well as the time from the start of heating the mixed solution to the addition of bismuth chloride to the mixed solution, were as shown in Table 1. Other than these, nickel particles were obtained in the same manner as in Example 1.
- Example 7 Copper sulfate pentahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the copper sulfate pentahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
- Example 8 Iron sulfate heptahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the iron sulfate heptahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
- Example 9 Sodium molybdate was added instead of bismuth chloride.
- the amounts of the aqueous palladium nitrate solution and the sodium molybdate added were as shown in Table 1.
- Nickel particles were obtained in the same manner as in Example 1 except for the above.
- Comparative Example 1 A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker.
- the polyethyleneimine was branched and had a number average molecular weight of 1800.
- the mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
- a magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
- 50 g of pure water was added and the dispersion was stirred for 10 minutes.
- the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed.
- the series of operations was repeated five times.
- 50 g of methanol was added and the dispersion was stirred for 10 minutes.
- the supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain a powder of nickel particles.
- Comparative Example 3 A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker.
- the polyethyleneimine was branched and had a number average molecular weight of 1800.
- the mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
- a magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition. After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
- X-ray photoelectron spectroscopy (XPS) measurement The sample to be measured for XPS was made by molding nickel particles into pellets using a press. In detail, about 10 mg of the particle sample was placed in an aluminum container having dimensions of ⁇ 5.2 mm and height 2.5 mm. Then, using a press (manufactured by AS ONE, product number: 1-312-01) and an adapter (product number: 1-312-03), pressure was applied together with the aluminum container at a predetermined stroke (25 mm). The nickel particle pellets supported by the aluminum container were then removed. The obtained pellet molded product was subjected to surface measurement and depth measurement from the sample surface to the inside by sputtering with Ar monomer ions. The measurement conditions were as follows.
- Measurement device VersaProbeIII manufactured by ULVAC-PHI, Inc.
- Excitation X-ray Monochromatic Al-K ⁇ ray (1486.7 eV)
- Output 50W
- Acceleration voltage 15 kV ⁇ X-ray irradiation diameter: 200 ⁇ m ⁇ ⁇ X-ray scanning area: 1000 ⁇ m ⁇ 300 ⁇ m
- Detection angle 45°
- Pass energy 26.0 eV
- Energy step 0.1 eV/step
- Sputter ion species Ar monomer ions
- Sputter rate 3.3 nm/min ( SiO2 equivalent)
- Sputtering interval 20 s
- Measurement elements C 1s , Ni 2p3 , Sn 3d5 , Bi 4f , Cu 2p , Fe 3p , Mo 3d Energy correction value: C—C bond and C—H bond in C 1s (284.8 eV)
- a-axis length and crystallite size Cs The a-axis length and crystallite size Cs of the nickel particles obtained in the examples and comparative examples were calculated using the WPPF method from the diffraction peaks derived from nickel obtained by X-ray diffraction measurement.
- the X-ray diffraction pattern obtained under the above measurement conditions was analyzed using analysis software under the following conditions.
- the analysis was corrected using data obtained from lanthanum hexaboride powder (SRM660 series), a standard material provided by the National Institute of Standards and Technology (NIST).
- SRM660 series lanthanum hexaboride powder
- NIST National Institute of Standards and Technology
- the a-axis length and crystallite size Cs were calculated using the WPPF method.
- TMA/SS6000 manufactured by Seiko Instruments Inc. was used as the TMA measuring device. 0.2-0.3 g of nickel particles were placed in a stainless steel mold container with a diameter of 5.0 mm, and a pressure of 92 MPa was applied to the nickel particles to produce a pellet. The pellet length of the obtained pellet was measured and used as the measurement target sample. This was set in the measuring device, and the sample was heated at 5°C/min under a load of 49 mN and an atmosphere of 1% by volume hydrogen/99% by volume nitrogen. Measurement was started from room temperature (25°C), and a graph showing the relationship between temperature and shrinkage rate (%) was obtained. The shrinkage start temperature was determined from the obtained graph.
- the surface roughness Rz of the sintered film was measured using a SURFCOM 130A.
- the measurement conditions were an evaluation length of 6.0 mm and a measurement speed of 0.6 mm/s.
- the nickel particles obtained in Examples 1 to 9 contain metallic bismuth, copper, iron, or molybdenum elements in their surface regions. Furthermore, the a-axis length of the nickel particles obtained in the examples was longer than the a-axis length of the nickel particles obtained in Comparative Example 1, which did not use compounds of bismuth, copper, iron, and molybdenum. From these results, it is understood that the nickel particles obtained in Examples 1 to 6 contain an alloy of nickel and bismuth in their surface regions. It is also understood that the nickel particles obtained in Example 7 contain an alloy of nickel and copper in their surface regions. It is also understood that the nickel particles obtained in Example 8 contain an alloy of nickel and iron in their surface regions.
- the nickel particles obtained in Example 9 contain an alloy of nickel and molybdenum in their surface regions. Furthermore, as is clear from the results shown in Table 1, the nickel particles obtained in Examples 1 to 9 exhibited a higher shrinkage initiation temperature than the nickel particles obtained in Comparative Examples 1 to 3. This shows that the nickel particles obtained in Examples 1 to 9 exhibit high sintering resistance. In particular, as is clear from the comparison between Examples 1 to 5 and Example 6, it is found that the resistivity of the sintered film obtained from the nickel particles can be controlled by controlling the amount of bismuth contained in the nickel particles.
- Example 1 to 6 in which nickel particles having a surface region in which an alloy of nickel and bismuth was formed were produced, the surface of the sintered film was smoother than in Comparative Example 2 in which an alloy of nickel and bismuth was formed over the entire nickel particle. This shows that the surface roughness of the sintered film is reduced by using nickel particles having a surface region containing an alloy of nickel and bismuth.
- the present invention provides nickel particles that are highly sinter-resistant without excessively increasing electrical resistance.
Abstract
According to the present invention, nickel particles comprise a surface region including an alloy of a metal element M and nickel. The metal element M is at least one type of element selected from bismuth, copper, iron, and molybdenum. The content of the metal element M relative to the nickel particles as a whole is from 0.09 mass% to 15.8 mass%. When a region from a topmost surface to a sputtering depth of 5 nm by SiO2 conversion is measured in the depth direction of the nickel particles by X-ray photoelectron spectroscopy analysis, the value of X/Y is from 0.5 to 35, where X (at%) is the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in said region, and Y (at%) is the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in said region when the nickel particles are measured by ICP emission spectrometry.
Description
本発明はニッケル粒子及びその製造方法に関する。
The present invention relates to nickel particles and a method for producing the same.
電子機器に用いられる積層セラミックコンデンサ（以下「ＭＬＣＣ」ともいう。）の内部電極の形成には、一般にニッケル粒子が用いられている。ＭＬＣＣの製造において、ニッケル粒子を含む内部電極と誘電体層との積層体を同時に焼成する場合、原料の焼結温度の違いにより、内部電極に欠陥が生じることがある。このような不都合を防ぐ目的で、ニッケル粒子の耐焼結性の向上が求められている。
Nickel particles are generally used to form the internal electrodes of multilayer ceramic capacitors (hereafter referred to as "MLCCs") used in electronic devices. In the manufacture of MLCCs, when a laminate of an internal electrode containing nickel particles and a dielectric layer is simultaneously fired, defects can occur in the internal electrodes due to differences in the sintering temperatures of the raw materials. To prevent such problems, there is a demand for improving the sintering resistance of nickel particles.
例えば特許文献１には、ＰＶＤ法又はＣＶＤ法によって得られたスズ又はビスマスを含むニッケル粉末をＭＬＣＣの内部電極の形成に用いる技術が開示されている。同文献には、ニッケル粉末にスズ等の非磁性金属を添加することでニッケルの結晶構造が歪み、これによって該ニッケル粉末の焼結温度が向上すると記載されている。
For example, Patent Document 1 discloses a technology in which nickel powder containing tin or bismuth obtained by the PVD or CVD method is used to form the internal electrodes of an MLCC. The document states that adding a non-magnetic metal such as tin to nickel powder distorts the crystal structure of the nickel, thereby increasing the sintering temperature of the nickel powder.
特許文献２には、略球形状の粒子形状を有し、スズによって表面処理がされているニッケル粉末を、ＭＬＣＣの内部電極の形成に用いる技術が開示されている。また、同文献には、スズに加えてビスマスを用いて表面処理することも開示されている。同文献には、同文献に記載のニッケル粉末によれば、その焼結挙動が改善されると記載されている。
Patent Document 2 discloses a technique for using nickel powder, which has a roughly spherical particle shape and is surface-treated with tin, to form the internal electrodes of an MLCC. The same document also discloses that surface treatment is performed using bismuth in addition to tin. The same document also describes that the sintering behavior is improved by using the nickel powder described in the document.
ところで、近年の電子機器の高性能化に伴い、ＭＬＣＣにおいては内部電極に発生し得る欠陥に起因した不都合を一層防ぐことが要求されている。この要求に応える目的で、ニッケル粒子は、耐焼結性が一層向上したものであることに加えて、該ニッケル粒子を用いて内部電極を形成したときに該電極の電気抵抗を過度に高めることのないものであることが望まれている。
したがって、本発明の課題は、電気抵抗を過度に高めることなく耐焼結性が高いニッケル粒子を提供することにある。 However, with the recent trend toward higher performance of electronic devices, there is a demand for further prevention of inconveniences caused by defects that may occur in the internal electrodes of MLCCs. In order to meet this demand, it is desirable for the nickel particles to have improved sintering resistance and, when the nickel particles are used to form an internal electrode, not to excessively increase the electrical resistance of the electrode.
Therefore, an object of the present invention is to provide nickel particles that have high sintering resistance without excessively increasing electrical resistance.
したがって、本発明の課題は、電気抵抗を過度に高めることなく耐焼結性が高いニッケル粒子を提供することにある。 However, with the recent trend toward higher performance of electronic devices, there is a demand for further prevention of inconveniences caused by defects that may occur in the internal electrodes of MLCCs. In order to meet this demand, it is desirable for the nickel particles to have improved sintering resistance and, when the nickel particles are used to form an internal electrode, not to excessively increase the electrical resistance of the electrode.
Therefore, an object of the present invention is to provide nickel particles that have high sintering resistance without excessively increasing electrical resistance.
本発明は、ニッケルと金属元素Ｍとの合金を含む表面域を有するニッケル粒子であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種であり、
前記ニッケル粒子全体に対する前記金属元素Ｍの含有量が０．０９質量％以上１５．８質量％以下であり、
Ｘ線光電子分光分析によって前記ニッケル粒子の深さ方向において最表面からＳｉＯ２換算でのスパッタ深さ５ｎｍまでの領域を測定したときに、該領域において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の最大値をＸ（ａｔ％）とし、
ＩＣＰ発光分光分析法によって前記ニッケル粒子を測定したとき、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合をＹ（ａｔ％）としたとき、
Ｘ／Ｙの値が０．５以上３５以下である、ニッケル粒子を提供するものである。 The present invention relates to a nickel particle having a surface region comprising an alloy of nickel and a metallic element M,
The metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
The content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
When a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy, the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%);
When the nickel particles are measured by ICP atomic emission spectrometry, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %),
The present invention provides nickel particles having a value of X/Y of 0.5 or more and 35 or less.
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種であり、
前記ニッケル粒子全体に対する前記金属元素Ｍの含有量が０．０９質量％以上１５．８質量％以下であり、
Ｘ線光電子分光分析によって前記ニッケル粒子の深さ方向において最表面からＳｉＯ２換算でのスパッタ深さ５ｎｍまでの領域を測定したときに、該領域において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の最大値をＸ（ａｔ％）とし、
ＩＣＰ発光分光分析法によって前記ニッケル粒子を測定したとき、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合をＹ（ａｔ％）としたとき、
Ｘ／Ｙの値が０．５以上３５以下である、ニッケル粒子を提供するものである。 The present invention relates to a nickel particle having a surface region comprising an alloy of nickel and a metallic element M,
The metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
The content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
When a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy, the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%);
When the nickel particles are measured by ICP atomic emission spectrometry, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %),
The present invention provides nickel particles having a value of X/Y of 0.5 or more and 35 or less.
また本発明は、水酸化ニッケル粒子、ポリオール、ポリビニルピロリドン及びポリエチレンイミンを含む混合液を加熱してニッケル粒子を製造する方法であって、
１質量部のポリエチレンイミンに対して、ポリビニルピロリドンを３０質量部以上２００質量部以下用い、
前記加熱によって前記水酸化ニッケル粒子をニッケル母粒子に還元し、
一部の前記水酸化ニッケル粒子が残存している状態で、前記混合液と金属元素Ｍの化合物とを混合し、該化合物を金属Ｍに還元して、前記ニッケル母粒子に、ニッケルと金属元素Ｍとの合金を含む表面域を形成する、ニッケル粒子の製造方法であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種である、ニッケル粒子の製造方法を提供するものである。 The present invention also provides a method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of:
Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine,
The heating reduces the nickel hydroxide particles to nickel base particles,
A method for producing nickel particles, comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
The metal element M is at least one element selected from the group consisting of bismuth, copper, iron and molybdenum.
１質量部のポリエチレンイミンに対して、ポリビニルピロリドンを３０質量部以上２００質量部以下用い、
前記加熱によって前記水酸化ニッケル粒子をニッケル母粒子に還元し、
一部の前記水酸化ニッケル粒子が残存している状態で、前記混合液と金属元素Ｍの化合物とを混合し、該化合物を金属Ｍに還元して、前記ニッケル母粒子に、ニッケルと金属元素Ｍとの合金を含む表面域を形成する、ニッケル粒子の製造方法であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種である、ニッケル粒子の製造方法を提供するものである。 The present invention also provides a method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of:
Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine,
The heating reduces the nickel hydroxide particles to nickel base particles,
A method for producing nickel particles, comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
The metal element M is at least one element selected from the group consisting of bismuth, copper, iron and molybdenum.
以下本発明を、その好ましい実施形態に基づき説明する。本発明のニッケル粒子は、ニッケル母粒子と、該母粒子の表面に位置するニッケルと金属元素Ｍとの合金（以下、「ニッケル・金属Ｍ合金」ともいう。）を含む表面域とを有している。本明細書における「ニッケル母粒子」とは、ニッケル元素から実質的に構成され、残部に不可避元素を含む粒子のことである。不可避元素は例えば大気中の酸素や二酸化炭素に由来する酸素元素及び炭素元素、並びにニッケル粒子の製造過程で混入することのある窒素元素等である。
The present invention will be described below based on its preferred embodiments. The nickel particles of the present invention have a nickel base particle and a surface region containing an alloy of nickel and metal element M (hereinafter also referred to as "nickel-metal M alloy") located on the surface of the base particle. In this specification, "nickel base particle" refers to a particle that is substantially composed of nickel element, with the remainder containing unavoidable elements. Examples of unavoidable elements include oxygen element and carbon element derived from oxygen and carbon dioxide in the air, and nitrogen element that may be mixed in during the manufacturing process of the nickel particles.
ニッケル粒子におけるニッケル母粒子は、その表面にニッケル・金属Ｍ合金を含む表面域を有している。本明細書において「ニッケル・金属Ｍ合金」とは、後述する金属元素Ｍを含むニッケル基合金のことである。ニッケル・金属Ｍ合金は、ニッケル元素と金属元素Ｍとの合金から実質的に構成され、残部に不可避元素を含む。ニッケル・金属Ｍ合金を含む表面域において、金属元素Ｍは、その一部が金属元素Ｍの単体の状態（すなわち金属の状態）で存在してもよい。あるいは金属元素Ｍは、その一部が金属元素Ｍの化合物の状態で存在してもよい。あるいは金属元素Ｍは、これらを二種以上組み合わせた状態で存在してもよい。金属元素Ｍが前記金属元素Ｍの化合物の状態でニッケル・金属Ｍ合金を含む表面域に存在している場合、該化合物としては例えば金属Ｍを含む酸化物、水酸化物、硫化物、硫酸化物、ホウ化物、リン化物等が挙げられるが、これらに限られない。尤もニッケル・金属Ｍ合金を含む表面域における金属元素Ｍは、実質的にニッケルとの合金のみからなることが、本発明のニッケル粒子が本来的に有する利点を最大限発揮させる観点から望ましい。本明細書において「実質的にニッケルとの合金のみからなる」とは、意図的にニッケルとの合金以外の金属元素Ｍを前記表面域が含むことを排除し、且つ、ニッケル粒子の製造過程において不可避的に混入する微量の金属元素Ｍの単体又は金属元素Ｍの化合物を許容する趣旨である。
The nickel mother particle in the nickel particle has a surface region containing a nickel-metal M alloy on its surface. In this specification, "nickel-metal M alloy" refers to a nickel-based alloy containing the metal element M described below. The nickel-metal M alloy is substantially composed of an alloy of nickel element and metal element M, and contains inevitable elements as the remainder. In the surface region containing the nickel-metal M alloy, the metal element M may be present in part in the state of the metal element M alone (i.e., in the state of metal). Alternatively, the metal element M may be present in part in the state of a compound of the metal element M. Alternatively, the metal element M may be present in a state of a combination of two or more of these. When the metal element M is present in the surface region containing the nickel-metal M alloy in the state of a compound of the metal element M, examples of the compound include, but are not limited to, oxides, hydroxides, sulfides, sulfates, borides, phosphides, etc. containing the metal M. However, it is desirable that the metal element M in the surface region containing the nickel-metal M alloy is substantially composed of only an alloy with nickel, from the viewpoint of maximizing the inherent advantages of the nickel particles of the present invention. In this specification, "consisting essentially of an alloy with nickel" excludes the surface region from intentionally containing metal elements M other than alloys with nickel, and allows for trace amounts of simple metal element M or compounds of metal element M that are inevitably mixed in during the manufacturing process of the nickel particles.
ニッケル粒子における金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種であることが好ましい。金属元素Ｍがビスマス、銅、鉄又はモリブデンであることで、ニッケル粒子の電気抵抗を過度に高めることなく耐焼結性を一層高めることができる。金属元素Ｍは、ビスマス、銅、鉄及びモリブデンのうちの１種のみを用いてもよく、あるいは２種以上の任意の組み合わせを用いてもよい。以下の説明において金属元素Ｍ（又は金属Ｍ）というときには、文脈に応じ、ビスマス、銅、鉄若しくはモリブデン又はこれらの任意の２種以上の組み合わせを意味する。
The metal element M in the nickel particles is preferably at least one selected from bismuth, copper, iron and molybdenum. When the metal element M is bismuth, copper, iron or molybdenum, the sintering resistance of the nickel particles can be further improved without excessively increasing the electrical resistance of the nickel particles. The metal element M may be only one of bismuth, copper, iron and molybdenum, or any combination of two or more of them. In the following description, when the metal element M (or metal M) is mentioned, it means bismuth, copper, iron or molybdenum, or any combination of two or more of them, depending on the context.
ニッケル粒子がその表面域にニッケル・金属Ｍ合金を含むことは、以下の方法によって確認できる。
具体的には、まずニッケル粒子がその表面域に金属元素Ｍを含み、該金属元素Ｍが主に金属状態であることを、Ｘ線光電子分光分析（以下「ＸＰＳ」ともいう。）による測定によって確認する。次いで、前記ニッケル粒子のＸ線回折ピークにおけるａ軸長が、ニッケル粒子のみを予め測定した得られたＸ線回折ピークにおけるａ軸長よりも伸びていることを確認する。Ｘ線回折ピークにおけるａ軸長が伸びることは、物質が固溶していることを意味する。したがって、ＸＰＳの測定によって確認された金属元素Ｍがニッケル粒子の表面域に金属状態で存在していることに加えて、ａ軸長の比較によって確認された金属元素Ｍとニッケルとが固溶していることから、該ニッケル粒子がその表面域にニッケル・金属Ｍ合金を含むことを確認できる。 Whether or not the nickel particles contain nickel-metal M alloy in their surface region can be confirmed by the following method.
Specifically, first, it is confirmed by X-ray photoelectron spectroscopy (hereinafter also referred to as "XPS") that the nickel particles contain the metal element M in their surface region and that the metal element M is mainly in a metallic state. Next, it is confirmed that the a-axis length in the X-ray diffraction peak of the nickel particles is longer than the a-axis length in the X-ray diffraction peak obtained by measuring only the nickel particles in advance. The extension of the a-axis length in the X-ray diffraction peak means that the substance is in a solid solution. Therefore, since the metal element M confirmed by the XPS measurement exists in a metallic state in the surface region of the nickel particles, and the metal element M and nickel are in a solid solution confirmed by comparing the a-axis lengths, it can be confirmed that the nickel particles contain a nickel-metal M alloy in their surface region.
具体的には、まずニッケル粒子がその表面域に金属元素Ｍを含み、該金属元素Ｍが主に金属状態であることを、Ｘ線光電子分光分析（以下「ＸＰＳ」ともいう。）による測定によって確認する。次いで、前記ニッケル粒子のＸ線回折ピークにおけるａ軸長が、ニッケル粒子のみを予め測定した得られたＸ線回折ピークにおけるａ軸長よりも伸びていることを確認する。Ｘ線回折ピークにおけるａ軸長が伸びることは、物質が固溶していることを意味する。したがって、ＸＰＳの測定によって確認された金属元素Ｍがニッケル粒子の表面域に金属状態で存在していることに加えて、ａ軸長の比較によって確認された金属元素Ｍとニッケルとが固溶していることから、該ニッケル粒子がその表面域にニッケル・金属Ｍ合金を含むことを確認できる。 Whether or not the nickel particles contain nickel-metal M alloy in their surface region can be confirmed by the following method.
Specifically, first, it is confirmed by X-ray photoelectron spectroscopy (hereinafter also referred to as "XPS") that the nickel particles contain the metal element M in their surface region and that the metal element M is mainly in a metallic state. Next, it is confirmed that the a-axis length in the X-ray diffraction peak of the nickel particles is longer than the a-axis length in the X-ray diffraction peak obtained by measuring only the nickel particles in advance. The extension of the a-axis length in the X-ray diffraction peak means that the substance is in a solid solution. Therefore, since the metal element M confirmed by the XPS measurement exists in a metallic state in the surface region of the nickel particles, and the metal element M and nickel are in a solid solution confirmed by comparing the a-axis lengths, it can be confirmed that the nickel particles contain a nickel-metal M alloy in their surface region.
ニッケル粒子がその表面域に金属元素Ｍを含む割合はＸＰＳによって測定できる。詳細には、ＸＰＳによってニッケル粒子の深さ方向において最表面からＳｉＯ２換算でのスパッタ深さ５ｎｍまでの領域（以下、この領域のことを「粒子表面領域」ともいう。）を測定したときに、該粒子表面領域において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の最大値であるＸの値が０．５ａｔ％以上であることが好ましい。前記の「最大値」とは、粒子表面領域の厚み方向に沿って測定された複数のＸの値が異なる場合における、当該Ｘの値の最大値のことをいう。Ｘの値が０．５ａｔ％以上である部位を有するように金属元素Ｍが存在していることが、後述するニッケル粒子の耐焼結性を一層高める観点から好ましい。
金属元素Ｍがビスマスである場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、３ａｔ％以上であることが一層好ましく、７ａｔ％以上であることが更に一層好ましく、１４ａｔ％以上であることが特に好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、３０ａｔ％以下であることが一層好ましく、２０ａｔ％以下であることが更に一層好ましく、１５ａｔ％以下であることが特に好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、４ａｔ％以上であることが一層好ましく、８ａｔ％以上であることが更に一層好ましく、１２ａｔ％以上であることが特に好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、２０ａｔ％以下であることが一層好ましく、１４ａｔ％以下であることが更に一層好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、４ａｔ％以上であることが一層好ましく、７ａｔ％以上であることが更に一層好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、３０ａｔ％以下であることが一層好ましく、２０ａｔ％以下であることが更に一層好ましく、９ａｔ％以下であることが特に好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、４ａｔ％以上であることが一層好ましく、８ａｔ％以上であることが更に一層好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、３０ａｔ％以下であることが一層好ましく、１０ａｔ％以下であることが更に一層好ましい。
Ｘの値の測定方法は後述する実施例において説明する。
前記の「ニッケル粒子の最表面」とは、ニッケル粒子の表面に例えば有機酸やアミン等の表面処理剤が存在している場合には、該表面処理剤を含んだニッケル粒子の最外面のことを指す。ニッケル粒子の表面に、表面処理剤が存在していない場合には、粒子の表面そのものを指す。 The proportion of the metal element M in the surface region of the nickel particles can be measured by XPS. In particular, when the region from the outermost surface to a sputter depth of 5 nm in terms of SiO2 in the depth direction of the nickel particles (hereinafter, this region is also referred to as the "particle surface region") is measured by XPS, it is preferable that the value of X, which is the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is 0.5 at% or more in the particle surface region. The "maximum value" refers to the maximum value of the value of X when multiple values of X measured along the thickness direction of the particle surface region are different. It is preferable that the metal element M exists so as to have a portion where the value of X is 0.5 at% or more from the viewpoint of further increasing the sintering resistance of the nickel particles described later.
When the metal element M is bismuth, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 3 at% or more, even more preferably 7 at% or more, and particularly preferably 14 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 15 at% or less.
When the metal element M is copper, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, even more preferably 8 at% or more, and particularly preferably 12 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 20 at% or less, and even more preferably 14 at% or less.
When the metal element M is iron, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 7 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 9 at% or less.
When the metal element M is molybdenum, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, further preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 8 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, further preferably 35 at% or less, even more preferably 30 at% or less, and even more preferably 10 at% or less.
The method for measuring the value of X will be explained in the Examples below.
The above-mentioned "outermost surface of nickel particles" refers to the outermost surface of nickel particles containing a surface treatment agent such as an organic acid or amine when the surface of the nickel particles is present. When no surface treatment agent is present on the surface of the nickel particles, the "outermost surface of nickel particles" refers to the surface of the particles themselves.
金属元素Ｍがビスマスである場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、３ａｔ％以上であることが一層好ましく、７ａｔ％以上であることが更に一層好ましく、１４ａｔ％以上であることが特に好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、３０ａｔ％以下であることが一層好ましく、２０ａｔ％以下であることが更に一層好ましく、１５ａｔ％以下であることが特に好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、４ａｔ％以上であることが一層好ましく、８ａｔ％以上であることが更に一層好ましく、１２ａｔ％以上であることが特に好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、２０ａｔ％以下であることが一層好ましく、１４ａｔ％以下であることが更に一層好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、４ａｔ％以上であることが一層好ましく、７ａｔ％以上であることが更に一層好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、３０ａｔ％以下であることが一層好ましく、２０ａｔ％以下であることが更に一層好ましく、９ａｔ％以下であることが特に好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、Ｘの値（ａｔ％）は、１ａｔ％以上であることがより好ましく、２ａｔ％以上であることが更に好ましく、４ａｔ％以上であることが一層好ましく、８ａｔ％以上であることが更に一層好ましい。また、Ｘの値（ａｔ％）は、７０ａｔ％以下であることがより好ましく、３５ａｔ％以下であることが更に好ましく、３０ａｔ％以下であることが一層好ましく、１０ａｔ％以下であることが更に一層好ましい。
Ｘの値の測定方法は後述する実施例において説明する。
前記の「ニッケル粒子の最表面」とは、ニッケル粒子の表面に例えば有機酸やアミン等の表面処理剤が存在している場合には、該表面処理剤を含んだニッケル粒子の最外面のことを指す。ニッケル粒子の表面に、表面処理剤が存在していない場合には、粒子の表面そのものを指す。 The proportion of the metal element M in the surface region of the nickel particles can be measured by XPS. In particular, when the region from the outermost surface to a sputter depth of 5 nm in terms of SiO2 in the depth direction of the nickel particles (hereinafter, this region is also referred to as the "particle surface region") is measured by XPS, it is preferable that the value of X, which is the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is 0.5 at% or more in the particle surface region. The "maximum value" refers to the maximum value of the value of X when multiple values of X measured along the thickness direction of the particle surface region are different. It is preferable that the metal element M exists so as to have a portion where the value of X is 0.5 at% or more from the viewpoint of further increasing the sintering resistance of the nickel particles described later.
When the metal element M is bismuth, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 3 at% or more, even more preferably 7 at% or more, and particularly preferably 14 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 15 at% or less.
When the metal element M is copper, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, even more preferably 8 at% or more, and particularly preferably 12 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 20 at% or less, and even more preferably 14 at% or less.
When the metal element M is iron, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, even more preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 7 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, even more preferably 35 at% or less, even more preferably 30 at% or less, even more preferably 20 at% or less, and particularly preferably 9 at% or less.
When the metal element M is molybdenum, from the same viewpoint as above, the value of X (at%) is more preferably 1 at% or more, further preferably 2 at% or more, even more preferably 4 at% or more, and even more preferably 8 at% or more. Also, the value of X (at%) is more preferably 70 at% or less, further preferably 35 at% or less, even more preferably 30 at% or less, and even more preferably 10 at% or less.
The method for measuring the value of X will be explained in the Examples below.
The above-mentioned "outermost surface of nickel particles" refers to the outermost surface of nickel particles containing a surface treatment agent such as an organic acid or amine when the surface of the nickel particles is present. When no surface treatment agent is present on the surface of the nickel particles, the "outermost surface of nickel particles" refers to the surface of the particles themselves.
ニッケル粒子は、該ニッケル粒子全体に対して、金属元素Ｍを０．０９質量％以上１５．８質量％以下含有することが好ましい。ニッケル粒子に対する金属元素Ｍの含有量がこの範囲内にあることで、ニッケル粒子の電気抵抗を過度に高めることなく耐焼結性を一層高めることができる。
金属元素Ｍがビスマスである場合、前記と同様の観点から、ニッケル粒子全体に対するビスマス元素の含有量は、０．３質量％以上であることがより好ましく、０．４質量％以上であることが更に好ましく、１質量％以上であることが一層好ましく、６．７質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対するビスマス元素の含有量は、１５．８質量％以下であることがより好ましく、１３質量％以下であることが更に好ましく、１１．４質量％以下であることが一層好ましく、１０質量％以下であることが更に一層好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、ニッケル粒子全体に対する銅元素の含有量は、０．４質量％以上であることがより好ましく、１質量％以上であることが更に好ましく、２．１質量％以上であることが一層好ましく、４．３質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対する銅元素の含有量は、１１．４質量％以下であることがより好ましく、７．６質量％以下であることが更に好ましく、６．５質量％以下であることが一層好ましく、６質量％以下であることが更に一層好ましく、５．４質量％以下であることが特に好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、ニッケル粒子全体に対する鉄元素の含有量は、０．０９質量％以上であることがより好ましく、０．２８質量％以上であることが更に好ましく、０．４０質量％以上であることが一層好ましく、０．４７質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対する鉄元素の含有量は、１１．４質量％以下であることがより好ましく、６質量％以下であることが更に好ましく、２．８７質量％以下であることが一層好ましく、１．９１質量％以下であることが更に一層好ましく、０．９６質量％以下であることが特に好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、ニッケル粒子全体に対するモリブデン元素の含有量は、０．４質量％以上であることがより好ましく、１質量％以上であることが更に好ましく、１．１質量％以上であることが一層好ましく、１．６質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対するモリブデン元素の含有量は、１１．４質量％以下であることがより好ましく、６．４質量％以下であることが更に好ましく、６質量％以下であることが一層好ましく、４．９質量％以下であることが更に一層好ましく、３．３質量％以下であることが特に好ましい。
ニッケル粒子全体に対する金属元素Ｍの含有量は、後述するＩＣＰ発光分光分析法によって測定することができる。 The nickel particles preferably contain 0.09% by mass or more and 15.8% by mass or less of the metal element M relative to the entire nickel particles. When the content of the metal element M relative to the nickel particles is within this range, the sintering resistance can be further improved without excessively increasing the electrical resistance of the nickel particles.
When the metal element M is bismuth, from the same viewpoint as above, the content of the bismuth element relative to the entire nickel particle is more preferably 0.3 mass% or more, even more preferably 0.4 mass% or more, even more preferably 1 mass% or more, and even more preferably 6.7 mass% or more. Also, the content of the bismuth element relative to the entire nickel particle is more preferably 15.8 mass% or less, even more preferably 13 mass% or less, even more preferably 11.4 mass% or less, and even more preferably 10 mass% or less.
When the metal element M is copper, from the same viewpoint as above, the content of copper element with respect to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 2.1 mass% or more, and even more preferably 4.3 mass% or more. Also, the content of copper element with respect to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 7.6 mass% or less, even more preferably 6.5 mass% or less, even more preferably 6 mass% or less, and particularly preferably 5.4 mass% or less.
When the metal element M is iron, from the same viewpoint as above, the content of the iron element relative to the entire nickel particle is more preferably 0.09% by mass or more, even more preferably 0.28% by mass or more, even more preferably 0.40% by mass or more, and even more preferably 0.47% by mass or more. Also, the content of the iron element relative to the entire nickel particle is more preferably 11.4% by mass or less, even more preferably 6% by mass or less, even more preferably 2.87% by mass or less, even more preferably 1.91% by mass or less, and particularly preferably 0.96% by mass or less.
When the metal element M is molybdenum, from the same viewpoint as above, the molybdenum element content relative to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 1.1 mass% or more, and even more preferably 1.6 mass% or more. Also, the molybdenum element content relative to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 6.4 mass% or less, even more preferably 6 mass% or less, even more preferably 4.9 mass% or less, and particularly preferably 3.3 mass% or less.
The content of the metal element M relative to the entire nickel particles can be measured by ICP emission spectrometry, which will be described later.
金属元素Ｍがビスマスである場合、前記と同様の観点から、ニッケル粒子全体に対するビスマス元素の含有量は、０．３質量％以上であることがより好ましく、０．４質量％以上であることが更に好ましく、１質量％以上であることが一層好ましく、６．７質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対するビスマス元素の含有量は、１５．８質量％以下であることがより好ましく、１３質量％以下であることが更に好ましく、１１．４質量％以下であることが一層好ましく、１０質量％以下であることが更に一層好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、ニッケル粒子全体に対する銅元素の含有量は、０．４質量％以上であることがより好ましく、１質量％以上であることが更に好ましく、２．１質量％以上であることが一層好ましく、４．３質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対する銅元素の含有量は、１１．４質量％以下であることがより好ましく、７．６質量％以下であることが更に好ましく、６．５質量％以下であることが一層好ましく、６質量％以下であることが更に一層好ましく、５．４質量％以下であることが特に好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、ニッケル粒子全体に対する鉄元素の含有量は、０．０９質量％以上であることがより好ましく、０．２８質量％以上であることが更に好ましく、０．４０質量％以上であることが一層好ましく、０．４７質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対する鉄元素の含有量は、１１．４質量％以下であることがより好ましく、６質量％以下であることが更に好ましく、２．８７質量％以下であることが一層好ましく、１．９１質量％以下であることが更に一層好ましく、０．９６質量％以下であることが特に好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、ニッケル粒子全体に対するモリブデン元素の含有量は、０．４質量％以上であることがより好ましく、１質量％以上であることが更に好ましく、１．１質量％以上であることが一層好ましく、１．６質量％以上であることが更に一層好ましい。また、ニッケル粒子全体に対するモリブデン元素の含有量は、１１．４質量％以下であることがより好ましく、６．４質量％以下であることが更に好ましく、６質量％以下であることが一層好ましく、４．９質量％以下であることが更に一層好ましく、３．３質量％以下であることが特に好ましい。
ニッケル粒子全体に対する金属元素Ｍの含有量は、後述するＩＣＰ発光分光分析法によって測定することができる。 The nickel particles preferably contain 0.09% by mass or more and 15.8% by mass or less of the metal element M relative to the entire nickel particles. When the content of the metal element M relative to the nickel particles is within this range, the sintering resistance can be further improved without excessively increasing the electrical resistance of the nickel particles.
When the metal element M is bismuth, from the same viewpoint as above, the content of the bismuth element relative to the entire nickel particle is more preferably 0.3 mass% or more, even more preferably 0.4 mass% or more, even more preferably 1 mass% or more, and even more preferably 6.7 mass% or more. Also, the content of the bismuth element relative to the entire nickel particle is more preferably 15.8 mass% or less, even more preferably 13 mass% or less, even more preferably 11.4 mass% or less, and even more preferably 10 mass% or less.
When the metal element M is copper, from the same viewpoint as above, the content of copper element with respect to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 2.1 mass% or more, and even more preferably 4.3 mass% or more. Also, the content of copper element with respect to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 7.6 mass% or less, even more preferably 6.5 mass% or less, even more preferably 6 mass% or less, and particularly preferably 5.4 mass% or less.
When the metal element M is iron, from the same viewpoint as above, the content of the iron element relative to the entire nickel particle is more preferably 0.09% by mass or more, even more preferably 0.28% by mass or more, even more preferably 0.40% by mass or more, and even more preferably 0.47% by mass or more. Also, the content of the iron element relative to the entire nickel particle is more preferably 11.4% by mass or less, even more preferably 6% by mass or less, even more preferably 2.87% by mass or less, even more preferably 1.91% by mass or less, and particularly preferably 0.96% by mass or less.
When the metal element M is molybdenum, from the same viewpoint as above, the molybdenum element content relative to the whole nickel particle is more preferably 0.4 mass% or more, more preferably 1 mass% or more, even more preferably 1.1 mass% or more, and even more preferably 1.6 mass% or more. Also, the molybdenum element content relative to the whole nickel particle is more preferably 11.4 mass% or less, even more preferably 6.4 mass% or less, even more preferably 6 mass% or less, even more preferably 4.9 mass% or less, and particularly preferably 3.3 mass% or less.
The content of the metal element M relative to the entire nickel particles can be measured by ICP emission spectrometry, which will be described later.
本発明のニッケル粒子は、ニッケル粒子全体に対する金属元素Ｍの含有量が上述の範囲を満たすことを条件として、該ニッケル粒子全体において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合であるＹの値（ａｔ％）は０．１ａｔ％以上７ａｔ％以下であることが好ましい。Ｙの値がこの範囲内となるように金属元素Ｍが存在していることが、ニッケル粒子の電気抵抗を過度に高めることなく耐焼結性を一層高める観点から好ましい。
金属元素Ｍがビスマスである場合、前記と同様の観点から、Ｙの値は、０．１ａｔ％以上であることがより好ましく、０．２ａｔ％以上であることが更に好ましく、０．３ａｔ％以上であることが一層好ましく、０．５ａｔ％以上であることが更に一層好ましく、２ａｔ％以上であることが特に好ましい。また、Ｙの値は、６ａｔ％以下であることがより好ましく、５ａｔ％以下であることが更に好ましく、４ａｔ％以下であることが一層好ましく、３ａｔ％以下であることが更に一層好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、Ｙの値は、０．２ａｔ％以上であることがより好ましく、０．５ａｔ％以上であることが更に好ましく、１ａｔ％以上であることが一層好ましく、２ａｔ％以上であることが更に一層好ましく、４ａｔ％以上であることが特に好ましい。また、Ｙの値は、７ａｔ％以下であることがより好ましく、６ａｔ％以下であることが更に好ましく、５ａｔ％以下であることが一層好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、Ｙの値は、０．１ａｔ％以上であることがより好ましく、０．２ａｔ％以上であることが更に好ましく、０．３ａｔ％以上であることが一層好ましく、０．５ａｔ％以上であることが更に一層好ましい。また、Ｙの値は、６ａｔ％以下であることがより好ましく、３ａｔ％以下であることが更に好ましく、２ａｔ％以下であることが一層好ましく、１ａｔ％以下であることが更に一層好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、Ｙの値は、０．２ａｔ％以上であることがより好ましく、０．３ａｔ％以上であることが更に好ましく、０．５ａｔ％以上であることが一層好ましく、０．７ａｔ％以上であることが更に一層好ましく、１ａｔ％以上であることが特に好ましい。また、Ｙの値は、６ａｔ％以下であることがより好ましく、４ａｔ％以下であることが更に好ましく、３ａｔ％以下であることが一層好ましく、２ａｔ％以下であることが更に一層好ましい。 In the nickel particles of the present invention, the content of the metal element M in the entire nickel particle satisfies the above-mentioned range, and the value of Y (at%), which is the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is preferably 0.1 at% or more and 7 at% or less in the entire nickel particle. It is preferable that the metal element M is present so that the value of Y is within this range, from the viewpoint of further increasing the sintering resistance without excessively increasing the electrical resistance of the nickel particle.
When the metal element M is bismuth, from the same viewpoint as above, the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, and particularly preferably 2 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 5 at% or less, even more preferably 4 at% or less, and even more preferably 3 at% or less.
When the metal element M is copper, from the same viewpoint as above, the value of Y is more preferably 0.2 at% or more, even more preferably 0.5 at% or more, even more preferably 1 at% or more, even more preferably 2 at% or more, and particularly preferably 4 at% or more. Also, the value of Y is more preferably 7 at% or less, even more preferably 6 at% or less, and even more preferably 5 at% or less.
When the metal element M is iron, from the same viewpoint as above, the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, and even more preferably 0.5 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 3 at% or less, even more preferably 2 at% or less, and even more preferably 1 at% or less.
When the metal element M is molybdenum, from the same viewpoint as above, the value of Y is more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, even more preferably 0.7 at% or more, and particularly preferably 1 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 4 at% or less, even more preferably 3 at% or less, and even more preferably 2 at% or less.
金属元素Ｍがビスマスである場合、前記と同様の観点から、Ｙの値は、０．１ａｔ％以上であることがより好ましく、０．２ａｔ％以上であることが更に好ましく、０．３ａｔ％以上であることが一層好ましく、０．５ａｔ％以上であることが更に一層好ましく、２ａｔ％以上であることが特に好ましい。また、Ｙの値は、６ａｔ％以下であることがより好ましく、５ａｔ％以下であることが更に好ましく、４ａｔ％以下であることが一層好ましく、３ａｔ％以下であることが更に一層好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、Ｙの値は、０．２ａｔ％以上であることがより好ましく、０．５ａｔ％以上であることが更に好ましく、１ａｔ％以上であることが一層好ましく、２ａｔ％以上であることが更に一層好ましく、４ａｔ％以上であることが特に好ましい。また、Ｙの値は、７ａｔ％以下であることがより好ましく、６ａｔ％以下であることが更に好ましく、５ａｔ％以下であることが一層好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、Ｙの値は、０．１ａｔ％以上であることがより好ましく、０．２ａｔ％以上であることが更に好ましく、０．３ａｔ％以上であることが一層好ましく、０．５ａｔ％以上であることが更に一層好ましい。また、Ｙの値は、６ａｔ％以下であることがより好ましく、３ａｔ％以下であることが更に好ましく、２ａｔ％以下であることが一層好ましく、１ａｔ％以下であることが更に一層好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、Ｙの値は、０．２ａｔ％以上であることがより好ましく、０．３ａｔ％以上であることが更に好ましく、０．５ａｔ％以上であることが一層好ましく、０．７ａｔ％以上であることが更に一層好ましく、１ａｔ％以上であることが特に好ましい。また、Ｙの値は、６ａｔ％以下であることがより好ましく、４ａｔ％以下であることが更に好ましく、３ａｔ％以下であることが一層好ましく、２ａｔ％以下であることが更に一層好ましい。 In the nickel particles of the present invention, the content of the metal element M in the entire nickel particle satisfies the above-mentioned range, and the value of Y (at%), which is the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M, is preferably 0.1 at% or more and 7 at% or less in the entire nickel particle. It is preferable that the metal element M is present so that the value of Y is within this range, from the viewpoint of further increasing the sintering resistance without excessively increasing the electrical resistance of the nickel particle.
When the metal element M is bismuth, from the same viewpoint as above, the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, and particularly preferably 2 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 5 at% or less, even more preferably 4 at% or less, and even more preferably 3 at% or less.
When the metal element M is copper, from the same viewpoint as above, the value of Y is more preferably 0.2 at% or more, even more preferably 0.5 at% or more, even more preferably 1 at% or more, even more preferably 2 at% or more, and particularly preferably 4 at% or more. Also, the value of Y is more preferably 7 at% or less, even more preferably 6 at% or less, and even more preferably 5 at% or less.
When the metal element M is iron, from the same viewpoint as above, the value of Y is more preferably 0.1 at% or more, even more preferably 0.2 at% or more, even more preferably 0.3 at% or more, and even more preferably 0.5 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 3 at% or less, even more preferably 2 at% or less, and even more preferably 1 at% or less.
When the metal element M is molybdenum, from the same viewpoint as above, the value of Y is more preferably 0.2 at% or more, even more preferably 0.3 at% or more, even more preferably 0.5 at% or more, even more preferably 0.7 at% or more, and particularly preferably 1 at% or more. Also, the value of Y is more preferably 6 at% or less, even more preferably 4 at% or less, even more preferably 3 at% or less, and even more preferably 2 at% or less.
ニッケル粒子全体に含まれる金属元素Ｍの原子数の割合であるＹの値はＩＣＰ発光分光分析法によって測定する。具体的には、まずＩＣＰ発光分光分析法によってニッケル粒子全体を測定し、ニッケル元素の含有割合及び金属元素Ｍの含有割合を求める。次いで、ニッケル元素の含有割合（質量％）をニッケル元素の原子量（５８．７）で除して、該含有割合をニッケル元素の原子数ＡＮｉに換算する。また、金属元素Ｍの含有割合（質量％）を金属元素Ｍの原子量（ビスマスは２０９、銅は６３．６、鉄は５５．９、モリブデンは９６）で除して、該含有割合を金属元素Ｍの原子数ＡＭに換算する。そして、ニッケル元素の原子数ＡＮｉと金属元素Ｍの原子数ＡＭに対する金属元素Ｍの原子数の割合（ＡＭ／（ＡＮｉ＋ＡＭ）×１００）を算出し、前記Ｙの値を求める。
The value of Y, which is the ratio of the number of atoms of the metal element M contained in the entire nickel particle, is measured by ICP atomic emission spectroscopy. Specifically, first, the entire nickel particle is measured by ICP atomic emission spectroscopy to determine the content ratio of the nickel element and the content ratio of the metal element M. Next, the content ratio of the nickel element (mass%) is divided by the atomic weight of the nickel element (58.7) to convert the content ratio to the atomic number A Ni of the nickel element. In addition, the content ratio of the metal element M (mass%) is divided by the atomic weight of the metal element M (bismuth is 209, copper is 63.6, iron is 55.9, and molybdenum is 96) to convert the content ratio to the atomic number A M of the metal element M. Then, the ratio of the number of atoms of the metal element M to the atomic number A Ni of the nickel element and the atomic number A M of the metal element M (A M / (A Ni +A M ) × 100) is calculated to obtain the value of Y.
本発明者の検討の結果Ｘの値とＹの値との関係が、ニッケル粒子の耐焼結性に影響を及ぼすことが判明した。詳細には、Ｘ／Ｙの値を０．５以上３５以下とすることで、焼結によってニッケル粒子の収縮が開始する温度が上昇すること、つまり耐焼結性が高くなることが判明した。耐焼結性が高い本発明のニッケル粒子は、これを用いて例えばＭＬＣＣを製造する場合に、製造の一工程である焼成工程において、ニッケル粒子の焼結により内部電極が収縮する温度を、誘電体粒子の焼結により誘電体層が収縮する温度に極力近づけることができる。内部電極と誘電体層とのそれぞれが収縮する温度の差を小さくすることは、焼成工程の昇温過程において、内部電極と誘電体層とが収縮する時間が重なる点から有利である。具体的には、ＭＬＣＣの焼成工程において、内部電極と誘電体層とが収縮する温度や収縮率の違いに起因するクラックやデラミネーション（内部電極と誘電体層の界面における層間剥離）といった構造欠陥の発生を効果的に防止し得る観点から有利である。
As a result of the inventor's investigation, it was found that the relationship between the value of X and the value of Y affects the sintering resistance of nickel particles. In detail, it was found that by setting the value of X/Y to 0.5 or more and 35 or less, the temperature at which the nickel particles start to shrink due to sintering increases, that is, the sintering resistance increases. When using the nickel particles of the present invention, which have high sintering resistance, to manufacture, for example, an MLCC, the temperature at which the internal electrodes shrink due to sintering of the nickel particles in the firing process, which is one of the manufacturing processes, can be made as close as possible to the temperature at which the dielectric layer shrinks due to sintering of the dielectric particles. Reducing the difference in temperature at which the internal electrodes and the dielectric layer shrink is advantageous because the time at which the internal electrodes and the dielectric layer shrink overlap during the temperature rise process in the firing process. Specifically, it is advantageous from the viewpoint of effectively preventing the occurrence of structural defects such as cracks and delamination (interlayer peeling at the interface between the internal electrodes and the dielectric layers) caused by the difference in temperature and shrinkage rate at which the internal electrodes and the dielectric layers shrink in the firing process of the MLCC.
金属元素Ｍがビスマスである場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、１．５以上であることがより好ましく、３．７以上であることが更に好ましく、４以上であることが一層好ましく、５以上であることが更に一層好ましく、７以上であることが特に好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、２５以下であることが更に好ましく、２０以下であることが一層好ましい。
金属元素Ｍが銅である場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、０．５以上であることがより好ましく、１以上であることが更に好ましく、１．５以上であることが一層好ましく、２以上であることが更に一層好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、１５以下であることが更に好ましく、１３以下であることが一層好ましく、１０以下であることが更に一層好ましく、７以下であることが特に好ましく、３以下であることが殊更好ましい。
金属元素Ｍが鉄である場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、１以上であることがより好ましく、１．５以上であることが更に好ましく、３．７以上であることが一層好ましく、５以上であることが更に一層好ましく、１０以上であることが特に好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、２５以下であることが更に好ましく、２０以下であることが一層好ましく、１５以下であることが更に一層好ましい。
金属元素Ｍがモリブデンである場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、１以上であることがより好ましく、１．５以上であることが更に好ましく、３以上であることが一層好ましく、３．７以上であることが更に一層好ましく、５以上であることが特に好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、１５以下であることが更に好ましく、１３以下であることが一層好ましく、１０以下であることが更に一層好ましく、７以下であることが特に好ましい。 When the metal element M is bismuth, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 4 or more, even more preferably 5 or more, and particularly preferably 7 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, and even more preferably 20 or less.
When the metal element M is copper, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 0.5 or more, even more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, particularly preferably 7 or less, and especially preferably 3 or less.
When the metal element M is iron, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 5 or more, and particularly preferably 10 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of making the above-mentioned advantages more prominent.
When the metal element M is molybdenum, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3 or more, even more preferably 3.7 or more, and particularly preferably 5 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, and particularly preferably 7 or less.
金属元素Ｍが銅である場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、０．５以上であることがより好ましく、１以上であることが更に好ましく、１．５以上であることが一層好ましく、２以上であることが更に一層好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、１５以下であることが更に好ましく、１３以下であることが一層好ましく、１０以下であることが更に一層好ましく、７以下であることが特に好ましく、３以下であることが殊更好ましい。
金属元素Ｍが鉄である場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、１以上であることがより好ましく、１．５以上であることが更に好ましく、３．７以上であることが一層好ましく、５以上であることが更に一層好ましく、１０以上であることが特に好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、２５以下であることが更に好ましく、２０以下であることが一層好ましく、１５以下であることが更に一層好ましい。
金属元素Ｍがモリブデンである場合、前記の利点を一層顕著なものとする観点から、ニッケル粒子におけるＸ／Ｙの値は、１以上であることがより好ましく、１．５以上であることが更に好ましく、３以上であることが一層好ましく、３．７以上であることが更に一層好ましく、５以上であることが特に好ましい。ニッケル粒子におけるＸ／Ｙの値は、３０以下であることがより好ましく、１５以下であることが更に好ましく、１３以下であることが一層好ましく、１０以下であることが更に一層好ましく、７以下であることが特に好ましい。 When the metal element M is bismuth, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 4 or more, even more preferably 5 or more, and particularly preferably 7 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, and even more preferably 20 or less.
When the metal element M is copper, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 0.5 or more, even more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, particularly preferably 7 or less, and especially preferably 3 or less.
When the metal element M is iron, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3.7 or more, even more preferably 5 or more, and particularly preferably 10 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, and even more preferably 15 or less, from the viewpoint of making the above-mentioned advantages more prominent.
When the metal element M is molybdenum, from the viewpoint of making the above-mentioned advantages more prominent, the value of X/Y in the nickel particles is more preferably 1 or more, even more preferably 1.5 or more, even more preferably 3 or more, even more preferably 3.7 or more, and particularly preferably 5 or more. The value of X/Y in the nickel particles is more preferably 30 or less, even more preferably 15 or less, even more preferably 13 or less, even more preferably 10 or less, and particularly preferably 7 or less.
粒子表面領域においては、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の値は深さ方向において一定でもよく、あるいは変動していてもよい。前記割合の値が深さ方向において一定でない場合、前記割合の値は例えばニッケル粒子の表面から中心に向かうにつれて連続的に又はステップ状に減少していてもよい。特に、ＸＰＳによってニッケル粒子の最表面からＳｉＯ２換算でのスパッタ深さ２０ｎｍまでの領域を測定したときに、前記割合の値が、最表面からスパッタ深さ２０ｎｍに向けて漸減していることが、ニッケル粒子の耐焼結性が更に一層高くなることから好ましい。この場合、ニッケル粒子の最表面からスパッタ深さ５ｎｍまでの領域における前記割合の最大値をＸとし、スパッタ深さ２０ｎｍにおける前記割合の最大値をＸ１としたとき、Ｘ／Ｘ１の値が０．１以上１５以下であることが、ニッケル粒子の耐焼結性の更に一層の向上の点から好ましい。
金属元素Ｍがビスマスである場合、Ｘ／Ｘ１の値は、前記と同様の観点から、１以上であることがより好ましく、１．５以上であることが更に好ましく、２以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、４以下であることが更に一層好ましく、３以下であることが特に好ましく、２．５以下であることが殊更好ましい。
金属元素Ｍが銅である場合、Ｘ／Ｘ１の値は、前記と同様の観点から、０．１以上であることがより好ましく、０．５以上であることが更に好ましく、１以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、５以下であることが更に一層好ましく、３以下であることが特に好ましい。
金属元素Ｍが鉄である場合、Ｘ／Ｘ１の値は、前記と同様の観点から、０．１以上であることがより好ましく、０．５以上であることが更に好ましく、１以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、５以下であることが更に一層好ましく、２以下であることが特に好ましい。
金属元素Ｍがモリブデンである場合、Ｘ／Ｘ１の値は、前記と同様の観点から、０．１以上であることがより好ましく、１以上であることが更に好ましく、２以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、５以下であることが更に一層好ましく、３以下であることが特に好ましい。
Ｘ１の測定方法は後述する実施例において説明する。 In the particle surface region, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M may be constant in the depth direction or may vary. When the value of the ratio is not constant in the depth direction, the value of the ratio may decrease continuously or stepwise from the surface of the nickel particle toward the center. In particular, when the region from the outermost surface of the nickel particle to a sputtering depth of 20 nm in terms of SiO 2 is measured by XPS, it is preferable that the value of the ratio gradually decreases from the outermost surface to a sputtering depth of 20 nm, since this further improves the sintering resistance of the nickel particle. In this case, when the maximum value of the ratio in the region from the outermost surface of the nickel particle to a sputtering depth of 5 nm is X and the maximum value of the ratio at a sputtering depth of 20 nm is X1, it is preferable that the value of X/X1 is 0.1 or more and 15 or less in terms of further improving the sintering resistance of the nickel particle.
When the metal element M is bismuth, from the same viewpoint as above, the value of X/X1 is more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more. In addition, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 4 or less, particularly preferably 3 or less, and especially preferably 2.5 or less.
When the metal element M is copper, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
When the metal element M is iron, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 2 or less.
When the metal element M is molybdenum, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 1 or more, and even more preferably 2 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
The method for measuring X1 will be explained in the Examples below.
金属元素Ｍがビスマスである場合、Ｘ／Ｘ１の値は、前記と同様の観点から、１以上であることがより好ましく、１．５以上であることが更に好ましく、２以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、４以下であることが更に一層好ましく、３以下であることが特に好ましく、２．５以下であることが殊更好ましい。
金属元素Ｍが銅である場合、Ｘ／Ｘ１の値は、前記と同様の観点から、０．１以上であることがより好ましく、０．５以上であることが更に好ましく、１以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、５以下であることが更に一層好ましく、３以下であることが特に好ましい。
金属元素Ｍが鉄である場合、Ｘ／Ｘ１の値は、前記と同様の観点から、０．１以上であることがより好ましく、０．５以上であることが更に好ましく、１以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、５以下であることが更に一層好ましく、２以下であることが特に好ましい。
金属元素Ｍがモリブデンである場合、Ｘ／Ｘ１の値は、前記と同様の観点から、０．１以上であることがより好ましく、１以上であることが更に好ましく、２以上であることが一層好ましい。また、Ｘ／Ｘ１の値は、１０以下であることがより好ましく、７．８以下であることが更に好ましく、６．１以下であることが一層好ましく、５以下であることが更に一層好ましく、３以下であることが特に好ましい。
Ｘ１の測定方法は後述する実施例において説明する。 In the particle surface region, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M may be constant in the depth direction or may vary. When the value of the ratio is not constant in the depth direction, the value of the ratio may decrease continuously or stepwise from the surface of the nickel particle toward the center. In particular, when the region from the outermost surface of the nickel particle to a sputtering depth of 20 nm in terms of SiO 2 is measured by XPS, it is preferable that the value of the ratio gradually decreases from the outermost surface to a sputtering depth of 20 nm, since this further improves the sintering resistance of the nickel particle. In this case, when the maximum value of the ratio in the region from the outermost surface of the nickel particle to a sputtering depth of 5 nm is X and the maximum value of the ratio at a sputtering depth of 20 nm is X1, it is preferable that the value of X/X1 is 0.1 or more and 15 or less in terms of further improving the sintering resistance of the nickel particle.
When the metal element M is bismuth, from the same viewpoint as above, the value of X/X1 is more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more. In addition, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 4 or less, particularly preferably 3 or less, and especially preferably 2.5 or less.
When the metal element M is copper, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
When the metal element M is iron, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 0.5 or more, and even more preferably 1 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 2 or less.
When the metal element M is molybdenum, from the same viewpoint as above, the value of X/X1 is more preferably 0.1 or more, even more preferably 1 or more, and even more preferably 2 or more. Moreover, the value of X/X1 is more preferably 10 or less, even more preferably 7.8 or less, even more preferably 6.1 or less, even more preferably 5 or less, and particularly preferably 3 or less.
The method for measuring X1 will be explained in the Examples below.
金属元素Ｍがビスマスである場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１．７以上であることが更に一層好ましく、２以上であることが特に好ましく、５以上であることが殊更好ましい。また、Ｘ１そのものの値は、１５以下であることがより好ましく、１０以下であることが更に好ましく、７以下であることが一層好ましい。
金属元素Ｍが銅である場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１以上であることが更に一層好ましく、１．７以上であることが特に好ましく、３以上であることが殊更好ましく、５以上であることが特に殊更好ましい。また、Ｘ１そのものの値は、２０以下であることがより好ましく、１５以下であることが更に好ましく、１０以下であることが一層好ましい。
金属元素Ｍが鉄である場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１以上であることが更に一層好ましく、１．７以上であることが特に好ましく、２以上であることが殊更好ましく、４以上であることが特に殊更好ましい。また、Ｘ１そのものの値は、１５以下であることがより好ましく、１０以下であることが更に好ましく、６以下であることが一層好ましい。
金属元素Ｍがモリブデンである場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１以上であることが更に一層好ましく、１．７以上であることが特に好ましく、２以上であることが殊更好ましく、４以上であることが特に殊更好ましい。また、Ｘ１そのものの値は、１５以下であることがより好ましく、１０以下であることが更に好ましく、６以下であることが一層好ましく、５以下であることが更に一層好ましい。 When the metal element M is bismuth, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1.7 or more, particularly preferably 2 or more, and especially preferably 5 or more. In addition, the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 7 or less.
When the metal element M is copper, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 3 or more, and even more particularly preferably 5 or more. In addition, the value of X1 itself is more preferably 20 or less, even more preferably 15 or less, and even more preferably 10 or less.
When the metal element M is iron, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 2 or more, and even more particularly preferably 4 or more. Moreover, the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 6 or less.
When the metal element M is molybdenum, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, especially preferably 2 or more, and especially especially preferably 4 or more. In addition, the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, even more preferably 6 or less, and even more preferably 5 or less.
金属元素Ｍが銅である場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１以上であることが更に一層好ましく、１．７以上であることが特に好ましく、３以上であることが殊更好ましく、５以上であることが特に殊更好ましい。また、Ｘ１そのものの値は、２０以下であることがより好ましく、１５以下であることが更に好ましく、１０以下であることが一層好ましい。
金属元素Ｍが鉄である場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１以上であることが更に一層好ましく、１．７以上であることが特に好ましく、２以上であることが殊更好ましく、４以上であることが特に殊更好ましい。また、Ｘ１そのものの値は、１５以下であることがより好ましく、１０以下であることが更に好ましく、６以下であることが一層好ましい。
金属元素Ｍがモリブデンである場合、Ｘ１そのものの値については、ニッケル粒子の耐焼結性を更に一層高くする観点から、０．２以上であることがより好ましく、０．５以上であることが更に好ましく、０．７以上であることが一層好ましく、１以上であることが更に一層好ましく、１．７以上であることが特に好ましく、２以上であることが殊更好ましく、４以上であることが特に殊更好ましい。また、Ｘ１そのものの値は、１５以下であることがより好ましく、１０以下であることが更に好ましく、６以下であることが一層好ましく、５以下であることが更に一層好ましい。 When the metal element M is bismuth, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1.7 or more, particularly preferably 2 or more, and especially preferably 5 or more. In addition, the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 7 or less.
When the metal element M is copper, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 3 or more, and even more particularly preferably 5 or more. In addition, the value of X1 itself is more preferably 20 or less, even more preferably 15 or less, and even more preferably 10 or less.
When the metal element M is iron, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, even more preferably 2 or more, and even more particularly preferably 4 or more. Moreover, the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, and even more preferably 6 or less.
When the metal element M is molybdenum, the value of X1 itself is, from the viewpoint of further increasing the sintering resistance of the nickel particles, more preferably 0.2 or more, even more preferably 0.5 or more, even more preferably 0.7 or more, even more preferably 1 or more, particularly preferably 1.7 or more, especially preferably 2 or more, and especially especially preferably 4 or more. In addition, the value of X1 itself is more preferably 15 or less, even more preferably 10 or less, even more preferably 6 or less, and even more preferably 5 or less.
本発明のニッケル粒子は、累積個数５０個数％における個数累積粒径であるＤ５０の値が２０ｎｍ以上２００ｎｍ以下であることが好ましい。換言すれば本発明のニッケル粒子は微粒であることが好ましい。ニッケル粒子の粒径Ｄ５０がこの範囲内であることによって、本発明のニッケル粒子を各種の用途、例えばＭＬＣＣの内部電極として用いた場合に、該内部電極間の短絡が起こりづらくなるという利点がある。この利点を一層顕著なものとする観点から、ニッケル粒子の粒径Ｄ５０は２０ｎｍ以上１５０ｎｍ以下であることがより好ましく、４０ｎｍ以上１５０ｎｍ以下であることが更に好ましく、４０ｎｍ以上１００ｎｍ以下であることが一層好ましい。ニッケル粒子の粒径Ｄ５０は、該ニッケル粒子を走査型電子顕微鏡（ＳＥＭ）で観察することによって測定される。詳細には、ニッケル粒子をＳＥＭによって拡大倍率５００００倍で撮影し、撮影されたニッケル粒子の面積を求める。その面積から円相当直径を算出する。算出された円相当直径に基づき粒度分布を求める。粒度分布は、グラフの横軸に円相当直径をとり、縦軸に個数頻度をとる。このようにして得られた粒度分布曲線において、累積個数５０個数％における個数累積粒径をＤ５０と定義する。
The nickel particles of the present invention preferably have a value of D50 , which is the number-cumulative particle diameter at 50% of the cumulative number, of 20 nm or more and 200 nm or less. In other words, the nickel particles of the present invention are preferably fine particles. When the nickel particles of the present invention have a particle diameter D50 within this range, there is an advantage that when the nickel particles of the present invention are used in various applications, for example, as internal electrodes of MLCCs, short circuits between the internal electrodes are less likely to occur. From the viewpoint of making this advantage more prominent, the particle diameter D50 of the nickel particles is more preferably 20 nm or more and 150 nm or less, even more preferably 40 nm or more and 150 nm or less, and even more preferably 40 nm or more and 100 nm or less. The particle diameter D50 of the nickel particles is measured by observing the nickel particles with a scanning electron microscope (SEM). In detail, the nickel particles are photographed with a SEM at a magnification of 50,000 times, and the area of the photographed nickel particles is calculated. The circle equivalent diameter is calculated from the area. The particle size distribution is calculated based on the calculated circle equivalent diameter. The particle size distribution is plotted on the horizontal axis of the graph representing the equivalent circle diameter and on the vertical axis representing the number frequency. In the particle size distribution curve thus obtained, the number-cumulative particle size at 50% by number of cumulative particles is defined as D50 .
前記の「粒度分布曲線」を得るに際しては、５０００個以上のニッケル粒子について円相当直径を求める。円相当直径の算出には、画像解析粒度分布測定ソフトウェア（株式会社マウンテック社製Ｍａｃ－Ｖｉｅｗ）を用いる。観察対象とするニッケル粒子の最小単位は、ＳＥＭによって、独立した一つの粒子として認められる粒子界面が観察されるか否かで判断する。したがって、複数個の粒子からなる凝集塊が観察されたとしても、該凝集塊に粒子界面が観察される場合は、該粒子界面によって画定される領域が一つの粒子であると認定する。
In obtaining the above-mentioned "particle size distribution curve," the circle equivalent diameter is determined for 5,000 or more nickel particles. The circle equivalent diameter is calculated using image analysis particle size distribution measurement software (Mac-View, manufactured by Mountec Co., Ltd.). The smallest unit of nickel particle to be observed is determined by whether or not a particle interface that can be recognized as an independent particle is observed using SEM. Therefore, even if an agglomerate consisting of multiple particles is observed, if a particle interface is observed in the agglomerate, the area defined by the particle interface is recognized as a single particle.
本発明のニッケル粒子は、微粒であることに加えて、粗大粒子の存在割合が小さいことが好ましい。粗大粒子の存在は、本発明のニッケル粒子を例えばＭＬＣＣの内部電極に用いた場合に、該内部電極間の短絡の一因となることがある。ニッケル粒子における粗大粒子の存在割合を低減することで、この短絡を効果的に防止することができる。この観点から、本発明のニッケル粒子においては、Ｄ５０の１．５倍以上の粒径を有する粒子の存在割合（以下「粗大粒子存在割合」ともいう。）が０．５個数％以下であることが好ましく、０．３個数％以下であることが更に好ましく、０．１個数％以下であることが一層好ましい。
粗大粒子存在割合は０％に近ければ近いほど、内部電極間の短絡発生の防止に有効であるが、０．０１％程度に粗大粒子存在割合が低ければ、内部電極間の短絡発生を効果的に防止できる。
粗大粒子の尺度として、Ｄ５０の１．５倍以上の粒径を有する粒子を選定した理由は、Ｄ５０の１．５倍以上の粒径では、導電膜を形成した際に導電膜の表面が粗くなる一因となり、そのことがＭＬＣＣの内部電極間の短絡発生とに極めて深く関与していることを本発明者が見出したことによるものである。 In addition to being fine, the nickel particles of the present invention preferably have a small proportion of coarse particles. When the nickel particles of the present invention are used, for example, in the internal electrodes of an MLCC, the presence of coarse particles may cause a short circuit between the internal electrodes. By reducing the proportion of coarse particles in the nickel particles, this short circuit can be effectively prevented. From this viewpoint, in the nickel particles of the present invention, the proportion of particles having a particle size of 1.5 times or more of D50 (hereinafter also referred to as "coarse particle proportion") is preferably 0.5% by number or less, more preferably 0.3% by number or less, and even more preferably 0.1% by number or less.
The closer the proportion of coarse particles is to 0%, the more effective it is in preventing short circuits between internal electrodes. However, if the proportion of coarse particles is as low as about 0.01%, short circuits between internal electrodes can be effectively prevented.
The reason why particles having a particle size 1.5 times or more of D50 are selected as the measure of coarse particles is that the inventors have found that particles having a particle size 1.5 times or more of D50 are one of the factors that cause the surface of a conductive film to become rough when a conductive film is formed, and that this is extremely deeply involved in the occurrence of short circuits between the internal electrodes of an MLCC.
粗大粒子存在割合は０％に近ければ近いほど、内部電極間の短絡発生の防止に有効であるが、０．０１％程度に粗大粒子存在割合が低ければ、内部電極間の短絡発生を効果的に防止できる。
粗大粒子の尺度として、Ｄ５０の１．５倍以上の粒径を有する粒子を選定した理由は、Ｄ５０の１．５倍以上の粒径では、導電膜を形成した際に導電膜の表面が粗くなる一因となり、そのことがＭＬＣＣの内部電極間の短絡発生とに極めて深く関与していることを本発明者が見出したことによるものである。 In addition to being fine, the nickel particles of the present invention preferably have a small proportion of coarse particles. When the nickel particles of the present invention are used, for example, in the internal electrodes of an MLCC, the presence of coarse particles may cause a short circuit between the internal electrodes. By reducing the proportion of coarse particles in the nickel particles, this short circuit can be effectively prevented. From this viewpoint, in the nickel particles of the present invention, the proportion of particles having a particle size of 1.5 times or more of D50 (hereinafter also referred to as "coarse particle proportion") is preferably 0.5% by number or less, more preferably 0.3% by number or less, and even more preferably 0.1% by number or less.
The closer the proportion of coarse particles is to 0%, the more effective it is in preventing short circuits between internal electrodes. However, if the proportion of coarse particles is as low as about 0.01%, short circuits between internal electrodes can be effectively prevented.
The reason why particles having a particle size 1.5 times or more of D50 are selected as the measure of coarse particles is that the inventors have found that particles having a particle size 1.5 times or more of D50 are one of the factors that cause the surface of a conductive film to become rough when a conductive film is formed, and that this is extremely deeply involved in the occurrence of short circuits between the internal electrodes of an MLCC.
本発明のニッケル粒子は、微粒であり、粗大粒子の存在割合が低いことに加えて、粒径が可能な限り均一であることが好ましい。換言すれば粒度分布曲線がシャープであることが好ましい。粒度分布曲線のシャープさは、粒径の変動係数によって評価できる。変動係数は、粒度分布における粒径の標準偏差をσ（ｎｍ）としたとき、（σ／Ｄ５０）×１００（％）で定義される値である。本発明のニッケル粒子は、この変動係数の値が１４％以下であることが、該ニッケル粒子から形成される導電膜の表面粗さを低くする観点から好ましい。導電膜の表面粗さを一層低くする観点から、変動係数は１３％以下であることが更に好ましく、１２％以下であることが一層好ましい。
変動係数は０％に近ければ近いほど、導電膜の表面粗さの低下に一層寄与するが、８％程度に変動係数が低ければ、十分に満足すべき程度に導電膜の表面粗さを低下させることができる。 The nickel particles of the present invention are preferably fine particles, have a low proportion of coarse particles, and have a particle size as uniform as possible. In other words, it is preferable that the particle size distribution curve is sharp. The sharpness of the particle size distribution curve can be evaluated by the coefficient of variation of the particle size. The coefficient of variation is a value defined as (σ/D 50 )×100(%), where σ (nm) is the standard deviation of the particle size in the particle size distribution. In the nickel particles of the present invention, the value of the coefficient of variation is preferably 14% or less, from the viewpoint of reducing the surface roughness of the conductive film formed from the nickel particles. From the viewpoint of further reducing the surface roughness of the conductive film, the coefficient of variation is more preferably 13% or less, and even more preferably 12% or less.
The closer the coefficient of variation is to 0%, the more it contributes to reducing the surface roughness of the conductive film. However, a coefficient of variation as low as about 8% can reduce the surface roughness of the conductive film to a sufficiently satisfactory degree.
変動係数は０％に近ければ近いほど、導電膜の表面粗さの低下に一層寄与するが、８％程度に変動係数が低ければ、十分に満足すべき程度に導電膜の表面粗さを低下させることができる。 The nickel particles of the present invention are preferably fine particles, have a low proportion of coarse particles, and have a particle size as uniform as possible. In other words, it is preferable that the particle size distribution curve is sharp. The sharpness of the particle size distribution curve can be evaluated by the coefficient of variation of the particle size. The coefficient of variation is a value defined as (σ/D 50 )×100(%), where σ (nm) is the standard deviation of the particle size in the particle size distribution. In the nickel particles of the present invention, the value of the coefficient of variation is preferably 14% or less, from the viewpoint of reducing the surface roughness of the conductive film formed from the nickel particles. From the viewpoint of further reducing the surface roughness of the conductive film, the coefficient of variation is more preferably 13% or less, and even more preferably 12% or less.
The closer the coefficient of variation is to 0%, the more it contributes to reducing the surface roughness of the conductive film. However, a coefficient of variation as low as about 8% can reduce the surface roughness of the conductive film to a sufficiently satisfactory degree.
本発明のニッケル粒子は、ニッケルの結晶性が高いことが好ましい。ニッケルの結晶性が高いことは、本発明のニッケル粒子が焼結して収縮が開始する温度が上昇することを意味する。換言すればニッケルの結晶性が高いことは、上述のとおり、該ニッケル粒子が高い耐焼結性を示すことを意味する。
ニッケルの結晶性は、粒径Ｄ５０（ｎｍ）に対する結晶子サイズＣｓ（ｎｍ）の比率であるＣｓ／Ｄ５０で評価する手法が、金属粉の技術分野においてしばしば用いられる。Ｃｓ／Ｄ５０の値が大きいほど、ニッケルはその結晶性が高いと評価できる。この観点から、本発明のニッケル粒子においては、Ｃｓ／Ｄ５０の値が０．３以上であることが好ましく、０．３４以上であることが更に好ましく、０．３７以上であることが一層好ましい。
Ｃｓ／Ｄ５０はその値が大きいほどニッケル粒子が焼結して収縮が開始する温度が上昇するところ、本発明においては、Ｃｓ／Ｄ５０の値が好ましくは０．６以下であれば、当該温度を十分に高くすることが可能であり、この観点からＣｓ／Ｄ５０の値は０．５５以下であることが更に好ましく、０．５２以下であることが一層好ましい。 The nickel particles of the present invention preferably have high nickel crystallinity. High nickel crystallinity means that the temperature at which the nickel particles of the present invention begin to shrink due to sintering increases. In other words, high nickel crystallinity means that the nickel particles have high sintering resistance, as described above.
In the technical field of metal powder, the crystallinity of nickel is often evaluated by Cs/D 50 , which is the ratio of the crystallite size Cs (nm) to the particle size D 50 (nm). The larger the Cs/D 50 value, the higher the crystallinity of the nickel can be evaluated. From this viewpoint, in the nickel particles of the present invention, the Cs/D 50 value is preferably 0.3 or more, more preferably 0.34 or more, and even more preferably 0.37 or more.
The larger the Cs/D 50 value, the higher the temperature at which nickel particles begin to sinter and shrink. In the present invention, however, if the Cs/D 50 value is preferably 0.6 or less, the temperature can be made sufficiently high, and from this viewpoint, the Cs/D 50 value is more preferably 0.55 or less, and even more preferably 0.52 or less.
ニッケルの結晶性は、粒径Ｄ５０（ｎｍ）に対する結晶子サイズＣｓ（ｎｍ）の比率であるＣｓ／Ｄ５０で評価する手法が、金属粉の技術分野においてしばしば用いられる。Ｃｓ／Ｄ５０の値が大きいほど、ニッケルはその結晶性が高いと評価できる。この観点から、本発明のニッケル粒子においては、Ｃｓ／Ｄ５０の値が０．３以上であることが好ましく、０．３４以上であることが更に好ましく、０．３７以上であることが一層好ましい。
Ｃｓ／Ｄ５０はその値が大きいほどニッケル粒子が焼結して収縮が開始する温度が上昇するところ、本発明においては、Ｃｓ／Ｄ５０の値が好ましくは０．６以下であれば、当該温度を十分に高くすることが可能であり、この観点からＣｓ／Ｄ５０の値は０．５５以下であることが更に好ましく、０．５２以下であることが一層好ましい。 The nickel particles of the present invention preferably have high nickel crystallinity. High nickel crystallinity means that the temperature at which the nickel particles of the present invention begin to shrink due to sintering increases. In other words, high nickel crystallinity means that the nickel particles have high sintering resistance, as described above.
In the technical field of metal powder, the crystallinity of nickel is often evaluated by Cs/D 50 , which is the ratio of the crystallite size Cs (nm) to the particle size D 50 (nm). The larger the Cs/D 50 value, the higher the crystallinity of the nickel can be evaluated. From this viewpoint, in the nickel particles of the present invention, the Cs/D 50 value is preferably 0.3 or more, more preferably 0.34 or more, and even more preferably 0.37 or more.
The larger the Cs/D 50 value, the higher the temperature at which nickel particles begin to sinter and shrink. In the present invention, however, if the Cs/D 50 value is preferably 0.6 or less, the temperature can be made sufficiently high, and from this viewpoint, the Cs/D 50 value is more preferably 0.55 or less, and even more preferably 0.52 or less.
結晶子サイズＣｓそのものの値については、ニッケル粒子が焼結して収縮が開始する温度を十分に高くする観点から、１５ｎｍ以上７０ｎｍ以下であることが好ましく、１８ｎｍ以上７０ｎｍ以下であることが更に好ましく、２０ｎｍ以上７０ｎｍ以下であることが一層好ましい。
The value of the crystallite size Cs itself is preferably 15 nm or more and 70 nm or less, more preferably 18 nm or more and 70 nm or less, and even more preferably 20 nm or more and 70 nm or less, from the viewpoint of sufficiently raising the temperature at which the nickel particles sinter and begin to shrink.
結晶子サイズの測定方法としては、金属粉の技術分野において様々なものが知られているところ、本明細書における結晶子サイズとはＷＰＰＦ（whole powder pattern fitting）法によって測定された値のことである。結晶子サイズの測定方法としては、ＷＰＰＦ法の他にシェラー法が知られているところ、結晶の歪みの程度が大きい場合には、シェラー法に基づき求められた結晶子サイズの値は信頼性に欠けるものとなることから、そのようなおそれが少ないＷＰＰＦ法を本発明では採用した。
ＷＰＰＦ法に基づくニッケルの結晶子サイズの測定方法の詳細については後述する実施例において説明する。 There are various methods for measuring crystallite size in the technical field of metal powder, and the crystallite size in this specification refers to the value measured by the WPPF (whole powder pattern fitting) method. In addition to the WPPF method, the Scherrer method is also known as a method for measuring crystallite size, and when the degree of distortion of the crystal is large, the value of the crystallite size obtained based on the Scherrer method is unreliable, so the WPPF method, which is less likely to cause such a problem, is adopted in the present invention.
Details of the method for measuring the nickel crystallite size based on the WPPF method will be described in the Examples below.
ＷＰＰＦ法に基づくニッケルの結晶子サイズの測定方法の詳細については後述する実施例において説明する。 There are various methods for measuring crystallite size in the technical field of metal powder, and the crystallite size in this specification refers to the value measured by the WPPF (whole powder pattern fitting) method. In addition to the WPPF method, the Scherrer method is also known as a method for measuring crystallite size, and when the degree of distortion of the crystal is large, the value of the crystallite size obtained based on the Scherrer method is unreliable, so the WPPF method, which is less likely to cause such a problem, is adopted in the present invention.
Details of the method for measuring the nickel crystallite size based on the WPPF method will be described in the Examples below.
本発明のニッケル粒子は、電気抵抗を過度に高めるものではないことが好ましい。そのようなニッケル粒子を例えばＭＬＣＣの内部電極に用いた場合、該ＭＬＣＣの性能をより向上させることができる。そこで電気抵抗を過度に高めないようにする目的で、ニッケル・金属Ｍ合金を含む表面域を有するニッケル粒子中における、純ニッケル成分が多くなるように、該ニッケル粒子の結晶構造をコントロールすることが好ましい。この観点から、本発明のニッケル粒子においては、ニッケルの結晶構造における結晶格子のａ軸長が３．５２０Å以上３．５２９Å以下であることが好ましく、３．５２２Å以上３．５２６Å以下であることが更に好ましく、３．５２３Å以上３．５２６Å以下であることが一層好ましく、３．５２４Å以上３．５２６Å以下であることが更に一層好ましい。
The nickel particles of the present invention preferably do not excessively increase electrical resistance. When such nickel particles are used, for example, in the internal electrodes of an MLCC, the performance of the MLCC can be further improved. Therefore, in order to prevent excessive increase in electrical resistance, it is preferable to control the crystal structure of the nickel particles so that the pure nickel component is increased in the nickel particles having a surface region containing nickel-metal M alloy. From this viewpoint, in the nickel particles of the present invention, the a-axis length of the crystal lattice in the nickel crystal structure is preferably 3.520 Å or more and 3.529 Å or less, more preferably 3.522 Å or more and 3.526 Å or less, even more preferably 3.523 Å or more and 3.526 Å or less, and even more preferably 3.524 Å or more and 3.526 Å or less.
ニッケル粒子の結晶構造における結晶格子のａ軸長は、後述する実施例に記載のとおり、ＣｕＫα１線を用いたＸ線回折装置によって測定することができる。解析には、後述する実施例に記載のとおり、ＷＰＰＦ法により求める。
The a-axis length of the crystal lattice in the crystal structure of nickel particles can be measured by an X-ray diffraction device using CuKα1 radiation, as described in the Examples below. For analysis, the length is determined by the WPPF method, as described in the Examples below.
本発明のニッケルの結晶構造における結晶子サイズや結晶格子のａ軸長は、例えば該ニッケル粒子がその表面域に金属元素Ｍを含む割合を調整したり、ニッケル粒子が有するニッケル・金属Ｍ合金を含む表面域の厚さを薄くしたりすることによって達成される。これに加えて、又はこれに代えて、後述するニッケル粒子の製造方法における条件を適切に調整することによっても達成される。
The crystallite size and a-axis length of the crystal lattice in the nickel crystal structure of the present invention can be achieved, for example, by adjusting the proportion of metal element M contained in the surface region of the nickel particles, or by reducing the thickness of the surface region of the nickel particles that contains the nickel-metal M alloy. In addition, or instead, they can also be achieved by appropriately adjusting the conditions in the manufacturing method of nickel particles described below.
本発明のニッケル粒子の耐焼結性の程度は、該ニッケル粒子を対象として熱機械分析（ＴＭＡ）によって評価できる。本発明において室温（２５℃）を基準とするＴＭＡ収縮率（％）が５％となる温度を、収縮開始温度と定義する。当該温度は４００℃以上であることが、ニッケル粒子の耐焼結性を更に一層高める点から好ましい。この利点を一層顕著なものとする観点から、４５０℃以上であることがより好ましく、５００℃以上であることが更に好ましく、５５０℃以上であることが一層好ましく、５７０℃以上であることが更に一層好ましい。
The degree of sintering resistance of the nickel particles of the present invention can be evaluated by subjecting the nickel particles to thermomechanical analysis (TMA). In the present invention, the temperature at which the TMA shrinkage rate (%) based on room temperature (25°C) is 5% is defined as the shrinkage start temperature. From the viewpoint of further increasing the sintering resistance of the nickel particles, it is preferable for the temperature to be 400°C or higher. From the viewpoint of making this advantage more prominent, it is more preferable for the temperature to be 450°C or higher, even more preferable for the temperature to be 500°C or higher, even more preferable for the temperature to be 550°C or higher, and even more preferable for the temperature to be 570°C or higher.
次に、本発明のニッケル粒子の好ましい製造方法について説明する。本製造方法においては、いわゆるポリオール法によってニッケル粒子を製造する。ポリオール法とは、還元剤を兼ねた溶媒としてポリオールを用いる方法である。ポリオール法においては、ニッケルの化学種をポリオール中に存在させた状態下に加熱を行うことでニッケル母粒子への還元反応を生じさせ、該還元反応の終了前に金属元素Ｍの化合物を混合し、更に加熱を行って金属Ｍへの還元反応を生じさせ、該ニッケル母粒子にニッケル・金属Ｍ合金を含む表面域を形成させる。
Next, a preferred method for producing the nickel particles of the present invention will be described. In this production method, nickel particles are produced by the so-called polyol method. The polyol method is a method in which a polyol is used as a solvent that also serves as a reducing agent. In the polyol method, nickel chemical species are present in a polyol and heating is performed to cause a reduction reaction to the nickel base particles, and before the reduction reaction is completed, a compound of metal element M is mixed and further heating is performed to cause a reduction reaction to metal M, forming a surface region containing a nickel-metal M alloy on the nickel base particles.
本製造方法においては、ニッケル粒子を生成させるためのニッケルの化学種として水酸化ニッケルを用いることが、目的とするニッケル粒子を首尾よく得られる観点から好ましい。水酸化ニッケルは、ポリオール、ポリビニルピロリドン（以下「ＰＶＰ」ともいう。）及びポリエチレンイミン（以下「ＰＥＩ」ともいう。）を含む混合液に添加される。取り扱い性の観点から、水酸化ニッケルとしては粒子状の形態を有するものを用いることが好ましい。
In this manufacturing method, it is preferable to use nickel hydroxide as the nickel species for producing nickel particles, from the viewpoint of successfully obtaining the desired nickel particles. Nickel hydroxide is added to a mixture containing polyol, polyvinylpyrrolidone (hereinafter also referred to as "PVP"), and polyethyleneimine (hereinafter also referred to as "PEI"). From the viewpoint of ease of handling, it is preferable to use nickel hydroxide in a particulate form.
混合液に含まれるポリオールは、上述のとおり、溶媒として用いられ且つ水酸化ニッケルの還元剤としても用いられる。
ポリオールとしては、例えばエチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、１，２－プロパンジオール、ジプロピレングリコール、１，２－ブタンジオール、１，３－ブタンジオール、１，４－ブタンジオール、２，３－ブタンジオール１，５－ペンタンジオール及びポリエチレングリコール等を用いることができる。これらのポリオールは単独で又は２種以上を組み合わせて用いることができる。これらのポリオールのうちエチレングリコールは、分子量に対してヒドロキシ基が占める割合が大きいために還元性能が高く、また常温で液状であり取り扱い性に優れることから好ましい。 As described above, the polyol contained in the mixed liquid is used as a solvent and also as a reducing agent for nickel hydroxide.
Examples of the polyol that can be used include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and polyethylene glycol. These polyols can be used alone or in combination of two or more. Among these polyols, ethylene glycol is preferred because it has a high reducing performance due to a large proportion of hydroxyl groups relative to the molecular weight, and is liquid at room temperature and therefore easy to handle.
ポリオールとしては、例えばエチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、１，２－プロパンジオール、ジプロピレングリコール、１，２－ブタンジオール、１，３－ブタンジオール、１，４－ブタンジオール、２，３－ブタンジオール１，５－ペンタンジオール及びポリエチレングリコール等を用いることができる。これらのポリオールは単独で又は２種以上を組み合わせて用いることができる。これらのポリオールのうちエチレングリコールは、分子量に対してヒドロキシ基が占める割合が大きいために還元性能が高く、また常温で液状であり取り扱い性に優れることから好ましい。 As described above, the polyol contained in the mixed liquid is used as a solvent and also as a reducing agent for nickel hydroxide.
Examples of the polyol that can be used include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, dipropylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, and polyethylene glycol. These polyols can be used alone or in combination of two or more. Among these polyols, ethylene glycol is preferred because it has a high reducing performance due to a large proportion of hydroxyl groups relative to the molecular weight, and is liquid at room temperature and therefore easy to handle.
ポリオールの使用量は、これを還元剤という観点で考えれば、混合液中の水酸化ニッケルの量に応じて適宜調整されればよいので、特段の限定を設ける必要性はない。一方、溶媒として機能させようとする場合には、混合液中のポリオールの濃度に応じて混合液の性状が変化するので、ある一定の適正な濃度範囲が存在する。この観点から混合液中のポリオールの濃度は５０質量％以上９９．８質量％以下の範囲に設定することが好ましい。
When considering the amount of polyol used as a reducing agent, it is sufficient to adjust it appropriately according to the amount of nickel hydroxide in the mixed solution, so there is no need to set any particular limit. On the other hand, when it is intended to function as a solvent, the properties of the mixed solution change depending on the concentration of polyol in the mixed solution, so there is a certain appropriate concentration range. From this perspective, it is preferable to set the concentration of polyol in the mixed solution in the range of 50% by mass or more and 99.8% by mass or less.
ＰＶＰは、水酸化ニッケルの分散剤として用いられる。ＰＶＰは分散剤としての効果が顕著であり、還元で生じたニッケル粒子の粒度分布をシャープにできるので好ましい。これらのＰＶＰの分子量は、その水溶性の程度や分散能に応じて適切に調整すればよい。混合液中におけるＰＶＰの量は、水酸化ニッケルをニッケルに換算した１００質量部に対して０．０１質量部以上３０質量部以下とすることが好ましい。この範囲に設定することで、混合液の粘度を過度に高くすることなく、分散効果を十分に発現させることができる。
PVP is used as a dispersant for nickel hydroxide. PVP is preferable because it has a significant effect as a dispersant and can sharpen the particle size distribution of nickel particles generated by reduction. The molecular weight of these PVPs can be appropriately adjusted depending on the degree of water solubility and dispersing ability. The amount of PVP in the mixed solution is preferably 0.01 to 30 parts by mass per 100 parts by mass of nickel hydroxide converted into nickel. By setting it in this range, the dispersing effect can be fully expressed without excessively increasing the viscosity of the mixed solution.
ＰＥＩは、混合液中にニッケルの核が生成している間、混合液中のニッケルイオンの数を減少させて、核生成と核成長とが同時に進行しないようにする働きを有する。この理由は、（ａ）ＰＥＩはニッケルイオンに対して相互作用を有する非共有電子対を有しており、ニッケルイオンと配位結合が可能であること、（ｂ）ＰＥＩは前記非共有電子対を多量に有していること、及び（ｃ）ＰＥＩは、混合液中に未溶解状態で存在している水酸化ニッケルの表面と相互作用が可能な水素結合部位を有していることによるものである。
PEI acts to reduce the number of nickel ions in the mixed solution while nickel nuclei are being generated in the mixed solution, preventing nucleation and nucleus growth from proceeding simultaneously. This is because (a) PEI has unshared electron pairs that interact with nickel ions and can form coordinate bonds with nickel ions, (b) PEI has a large amount of the unshared electron pairs, and (c) PEI has hydrogen bonding sites that can interact with the surface of nickel hydroxide that is present in an undissolved state in the mixed solution.
ＰＥＩが混合液中に存在していることによって、ニッケルの核生成と、生成した核の成長とを順次行うことが可能になる。その結果、微粒で且つ均一な粒径を有するニッケル粒子が首尾よく得られる。このこととは対照的に、還元による従来のニッケル粒子の製造においては、核生成と核成長とが同時に生じるので、粗大粒子が生成しやすく、その上、粒径にばらつきが生じやすい。
以上の観点から、ＰＥＩとして、直鎖状のものを用いるよりも、分岐鎖状のものを用いることが有利である。同様の観点から、数平均分子量が６００以上１００００以下、特に８００以上５０００以下、とりわけ１０００以上３０００以下であるＰＥＩを用いることも好ましい。 The presence of PEI in the mixture allows nickel nucleation and subsequent growth of the nuclei, resulting in the successful production of nickel particles with fine and uniform particle size. In contrast, in the conventional production of nickel particles by reduction, nucleation and growth occur simultaneously, which tends to result in the production of coarse particles and uneven particle size.
From the above viewpoints, it is more advantageous to use branched PEI than linear PEI. From the same viewpoints, it is also preferable to use PEI having a number average molecular weight of 600 to 10,000, particularly 800 to 5,000, and especially 1,000 to 3,000.
以上の観点から、ＰＥＩとして、直鎖状のものを用いるよりも、分岐鎖状のものを用いることが有利である。同様の観点から、数平均分子量が６００以上１００００以下、特に８００以上５０００以下、とりわけ１０００以上３０００以下であるＰＥＩを用いることも好ましい。 The presence of PEI in the mixture allows nickel nucleation and subsequent growth of the nuclei, resulting in the successful production of nickel particles with fine and uniform particle size. In contrast, in the conventional production of nickel particles by reduction, nucleation and growth occur simultaneously, which tends to result in the production of coarse particles and uneven particle size.
From the above viewpoints, it is more advantageous to use branched PEI than linear PEI. From the same viewpoints, it is also preferable to use PEI having a number average molecular weight of 600 to 10,000, particularly 800 to 5,000, and especially 1,000 to 3,000.
特に本製造方法においては、混合液に含まれるＰＶＰとＰＥＩとの比率を特定の範囲に設定することで、ニッケルの核生成と、核成長とを順次行うことが確実になる。詳細には、１質量部のＰＥＩに対して、ＰＶＰを３０質量部以上２００質量部以下用いることが好ましく、４０質量部以上１５０質量部以下用いることが更に好ましく、５０質量部以上１３０質量部以下用いることが一層好ましい。
In particular, in this manufacturing method, by setting the ratio of PVP and PEI contained in the mixed solution within a specific range, it is possible to ensure that nickel nucleation and nucleus growth occur sequentially. In detail, it is preferable to use 30 to 200 parts by mass of PVP per 1 part by mass of PEI, more preferably 40 to 150 parts by mass, and even more preferably 50 to 130 parts by mass.
混合液中のＰＥＩの量は、ＰＶＰとＰＥＩとの比率が上述の範囲を満たすことを条件として、ＰＶＰの量に応じて適切に設定される。
The amount of PEI in the mixture is set appropriately according to the amount of PVP, provided that the ratio of PVP to PEI satisfies the above-mentioned range.
混合液には貴金属触媒を含有させることもできる。これによって、還元の初期段階において貴金属の微細な核粒子が生成し、その核粒子を起点としてニッケルが円滑に還元するようになる。貴金属触媒としては、例えば貴金属の水溶性塩等の貴金属化合物を用いることができる。貴金属の水溶性塩の例としては、パラジウム、銀、白金、金等の水溶性塩が挙げられる。貴金属としてパラジウムを用いる場合には、例えば塩化パラジウム、硝酸パラジウム、酢酸パラジウム、塩化アンモニウムパラジウム等を用いることができる。銀を用いる場合には、例えば硝酸銀、乳酸銀、酸化銀、硫酸銀、シクロヘキサン酸銀、酢酸銀等を用いることができる。白金を用いる場合には、例えば塩化白金酸、塩化白金酸カリウム、塩化白金酸ナトリウム等を用いることができる。金を用いる場合には、例えば塩化金酸、塩化金酸ナトリウム等を用いることができる。これらのうち、硝酸パラジウム、酢酸パラジウム、硝酸銀及び酢酸銀は、安価で経済性がよいので好ましく用いられる。貴金属触媒は、前記の化合物の形態で又は該化合物を水に溶解させた水溶液の形態で添加して用いることができる。混合液に含有させる貴金属触媒の量は、水酸化ニッケルをニッケルに換算した１００質量部に対して０．０１質量部以上５質量部以下、特に０．０１質量部以上１質量部以下であることが好ましい。
The mixture can also contain a precious metal catalyst. This generates fine nuclear particles of the precious metal in the initial stage of reduction, and the nickel is reduced smoothly from the nuclear particles. As the precious metal catalyst, for example, a precious metal compound such as a water-soluble salt of the precious metal can be used. Examples of water-soluble salts of precious metals include water-soluble salts of palladium, silver, platinum, gold, etc. When palladium is used as the precious metal, for example, palladium chloride, palladium nitrate, palladium acetate, ammonium palladium chloride, etc. can be used. When silver is used, for example, silver nitrate, silver lactate, silver oxide, silver sulfate, silver cyclohexanoate, silver acetate, etc. can be used. When platinum is used, for example, chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, etc. can be used. When gold is used, for example, chloroauric acid, sodium chloroaurate, etc. can be used. Of these, palladium nitrate, palladium acetate, silver nitrate, and silver acetate are preferably used because they are inexpensive and economical. The precious metal catalyst can be added in the form of the above-mentioned compound or in the form of an aqueous solution in which the compound is dissolved in water. The amount of precious metal catalyst contained in the mixed solution is preferably 0.01 to 5 parts by mass, particularly 0.01 to 1 part by mass, per 100 parts by mass of nickel hydroxide converted to nickel.
以上の各成分を含む混合液を撹拌しながら加熱して、水酸化ニッケルの還元を行う。加熱温度は、使用するポリオールの種類にもよるが、大気圧下において好ましくは１５０℃以上２００℃以下、更に好ましくは１７０℃以上２００℃以下、一層好ましくは１９０℃以上２００℃以下で加熱することによって、水酸化ニッケルのニッケル母粒子への還元を首尾よく行うことができる。
The mixture containing the above components is heated with stirring to reduce the nickel hydroxide. The heating temperature depends on the type of polyol used, but by heating at atmospheric pressure at a temperature preferably between 150°C and 200°C, more preferably between 170°C and 200°C, and even more preferably between 190°C and 200°C, the nickel hydroxide can be successfully reduced to nickel mother particles.
次に、水酸化ニッケルの還元反応が終了する前に、前記混合液に金属元素Ｍの化合物を混合する。換言すれば一部の水酸化ニッケルが残存している状態で、前記混合液に金属元素Ｍの化合物を混合する。ここでいう「水酸化ニッケルの還元反応が終了する前」とは、仕込み量の水酸化ニッケルに対して８０ｍｏｌ％以上が還元される前のことをいう。
金属元素Ｍがビスマスである場合、後述する金属元素Ｍの化合物の還元反応において、ニッケル母粒子にニッケル・金属Ｍ合金を含む表面域を首尾よく形成させる観点から、該化合物としては硝酸ビスマス、塩化ビスマス、硝酸ビスマス５水和物、水酸化ビスマス、酸化ビスマス及び炭酸ビスマスからなる群より選ばれる少なくとも一種を用いることが好ましく、塩化ビスマスを用いることが特に好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、該化合物としては硝酸銅３水和物、硫酸銅５水和物、酢酸銅１水和物、水酸化銅、亜酸化銅及び酸化銅からなる群より選ばれる少なくとも一種を用いることが好ましく、硫酸銅５水和物を用いることが特に好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、該化合物としては硝酸鉄９水和物、塩化鉄６水和物、硫酸鉄７水和物、水酸化鉄及び酸化鉄からなる群より選ばれる少なくとも一種を用いることが好ましく、硫酸鉄７水和物を用いることが特に好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、該化合物としてはモリブデン酸ナトリウム、モリブデン酸カリウム、モリブデン酸カルシウム及びモリブデン酸アンモニウムからなる群より選ばれる少なくとも一種を用いることが好ましく、モリブデン酸ナトリウムを用いることが特に好ましい。 Next, before the reduction reaction of nickel hydroxide is completed, a compound of metal element M is mixed into the mixed solution. In other words, the compound of metal element M is mixed into the mixed solution while some nickel hydroxide remains. Here, "before the reduction reaction of nickel hydroxide is completed" refers to before 80 mol % or more of the charged amount of nickel hydroxide is reduced.
When the metal element M is bismuth, from the viewpoint of successfully forming a surface region containing a nickel-metal M alloy on the nickel base particle in the reduction reaction of a compound of the metal element M described below, it is preferable to use at least one compound selected from the group consisting of bismuth nitrate, bismuth chloride, bismuth nitrate pentahydrate, bismuth hydroxide, bismuth oxide and bismuth carbonate, and it is particularly preferable to use bismuth chloride.
When the metal element M is copper, from the same viewpoint as above, it is preferable to use, as the compound, at least one selected from the group consisting of copper nitrate trihydrate, copper sulfate pentahydrate, copper acetate monohydrate, copper hydroxide, cuprous oxide, and copper oxide, and it is particularly preferable to use copper sulfate pentahydrate.
When the metal element M is iron, from the same viewpoint as above, it is preferable to use as the compound at least one selected from the group consisting of iron nitrate nonahydrate, iron chloride hexahydrate, iron sulfate heptahydrate, iron hydroxide, and iron oxide, and it is particularly preferable to use iron sulfate heptahydrate.
When the metal element M is molybdenum, from the same viewpoint as above, it is preferable to use as the compound at least one selected from the group consisting of sodium molybdate, potassium molybdate, calcium molybdate, and ammonium molybdate, and it is particularly preferable to use sodium molybdate.
金属元素Ｍがビスマスである場合、後述する金属元素Ｍの化合物の還元反応において、ニッケル母粒子にニッケル・金属Ｍ合金を含む表面域を首尾よく形成させる観点から、該化合物としては硝酸ビスマス、塩化ビスマス、硝酸ビスマス５水和物、水酸化ビスマス、酸化ビスマス及び炭酸ビスマスからなる群より選ばれる少なくとも一種を用いることが好ましく、塩化ビスマスを用いることが特に好ましい。
金属元素Ｍが銅である場合、前記と同様の観点から、該化合物としては硝酸銅３水和物、硫酸銅５水和物、酢酸銅１水和物、水酸化銅、亜酸化銅及び酸化銅からなる群より選ばれる少なくとも一種を用いることが好ましく、硫酸銅５水和物を用いることが特に好ましい。
金属元素Ｍが鉄である場合、前記と同様の観点から、該化合物としては硝酸鉄９水和物、塩化鉄６水和物、硫酸鉄７水和物、水酸化鉄及び酸化鉄からなる群より選ばれる少なくとも一種を用いることが好ましく、硫酸鉄７水和物を用いることが特に好ましい。
金属元素Ｍがモリブデンである場合、前記と同様の観点から、該化合物としてはモリブデン酸ナトリウム、モリブデン酸カリウム、モリブデン酸カルシウム及びモリブデン酸アンモニウムからなる群より選ばれる少なくとも一種を用いることが好ましく、モリブデン酸ナトリウムを用いることが特に好ましい。 Next, before the reduction reaction of nickel hydroxide is completed, a compound of metal element M is mixed into the mixed solution. In other words, the compound of metal element M is mixed into the mixed solution while some nickel hydroxide remains. Here, "before the reduction reaction of nickel hydroxide is completed" refers to before 80 mol % or more of the charged amount of nickel hydroxide is reduced.
When the metal element M is bismuth, from the viewpoint of successfully forming a surface region containing a nickel-metal M alloy on the nickel base particle in the reduction reaction of a compound of the metal element M described below, it is preferable to use at least one compound selected from the group consisting of bismuth nitrate, bismuth chloride, bismuth nitrate pentahydrate, bismuth hydroxide, bismuth oxide and bismuth carbonate, and it is particularly preferable to use bismuth chloride.
When the metal element M is copper, from the same viewpoint as above, it is preferable to use, as the compound, at least one selected from the group consisting of copper nitrate trihydrate, copper sulfate pentahydrate, copper acetate monohydrate, copper hydroxide, cuprous oxide, and copper oxide, and it is particularly preferable to use copper sulfate pentahydrate.
When the metal element M is iron, from the same viewpoint as above, it is preferable to use as the compound at least one selected from the group consisting of iron nitrate nonahydrate, iron chloride hexahydrate, iron sulfate heptahydrate, iron hydroxide, and iron oxide, and it is particularly preferable to use iron sulfate heptahydrate.
When the metal element M is molybdenum, from the same viewpoint as above, it is preferable to use as the compound at least one selected from the group consisting of sodium molybdate, potassium molybdate, calcium molybdate, and ammonium molybdate, and it is particularly preferable to use sodium molybdate.
金属元素Ｍがビスマスである場合、ニッケル母粒子にニッケルとビスマスとの合金を含む表面域を首尾よく形成させる観点から、混合液中におけるビスマス化合物の量はビスマスに換算して、仕込みの１質量部のニッケル量に対して、０．００３質量部以上とすることが好ましく、０．００４質量部以上とすることがより好ましく、０．０１質量部以上とすることが更に好ましく、０．０２質量部以上とすることが一層好ましい。また、混合液中におけるビスマス化合物の量はビスマスに換算して、仕込みの１質量部のニッケル量に対して、０．２０質量部以下とすることが好ましく、０．１６質量部以下とすることがより好ましく、０．１３質量部以下とすることが更に好ましく、０．１２質量部以下とすることが一層好ましい。
When the metal element M is bismuth, from the viewpoint of successfully forming a surface region containing an alloy of nickel and bismuth on the nickel mother particles, the amount of the bismuth compound in the mixed solution, converted into bismuth, is preferably 0.003 parts by mass or more per part by mass of nickel in the feed, more preferably 0.004 parts by mass or more, even more preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, per part by mass of nickel in the feed. Also, the amount of the bismuth compound in the mixed solution, converted into bismuth, is preferably 0.20 parts by mass or less per part by mass of nickel in the feed, more preferably 0.16 parts by mass or less, even more preferably 0.13 parts by mass or less, and even more preferably 0.12 parts by mass or less, per part by mass of nickel in the feed.
金属元素Ｍが銅である場合、ニッケル母粒子にニッケルと銅との合金を含む表面域を首尾よく形成させる観点から、混合液中における銅化合物の量は銅に換算して、仕込みの１質量部のニッケル量に対して、０．００４質量部以上とすることが好ましく、０．０１質量部以上とすることがより好ましく、０．０２２質量部以上とすることが更に好ましく、０．０４５質量部以上とすることが一層好ましい。また、混合液中における銅化合物の量は銅に換算して、仕込みの１質量部のニッケル量に対して、０．１２質量部以下とすることが好ましく、０．０８２質量部以下とすることがより好ましく、０．０７質量部以下とすることが更に好ましく、０．０６質量部以下とすることが一層好ましい。
When the metal element M is copper, from the viewpoint of successfully forming a surface region containing an alloy of nickel and copper on the nickel mother particles, the amount of the copper compound in the mixed solution, converted into copper, is preferably 0.004 parts by mass or more per part by mass of nickel in the feed, more preferably 0.01 parts by mass or more, even more preferably 0.022 parts by mass or more, and even more preferably 0.045 parts by mass or more, per part by mass of nickel in the feed. Also, the amount of the copper compound in the mixed solution, converted into copper, is preferably 0.12 parts by mass or less per part by mass of nickel in the feed, more preferably 0.082 parts by mass or less, even more preferably 0.07 parts by mass or less, and even more preferably 0.06 parts by mass or less, per part by mass of nickel in the feed.
金属元素Ｍが鉄である場合、ニッケル母粒子にニッケルと鉄との合金を含む表面域を首尾よく形成させる観点から、混合液中における鉄化合物の量は鉄に換算して、仕込みの１質量部のニッケル量に対して、０．０００９質量部以上とすることが好ましく、０．００２８質量部以上とすることがより好ましく、０．００４質量部以上とすることが更に好ましく、０．００４７質量部以上とすることが一層好ましい。また、混合液中における鉄化合物の量は鉄に換算して、仕込みの１質量部のニッケル量に対して、０．１２質量部以下とすることが好ましく、０．０８質量部以下とすることがより好ましく、０．０６質量部以下とすることが更に好ましく、０．０３０質量部以下とすることが一層好ましく、０．０２０質量部以下とすることが更に一層好ましい。
When the metal element M is iron, from the viewpoint of successfully forming a surface region containing an alloy of nickel and iron on the nickel mother particles, the amount of iron compounds in the mixed solution, converted into iron, is preferably 0.0009 parts by mass or more per part by mass of nickel in the feed, more preferably 0.0028 parts by mass or more, even more preferably 0.004 parts by mass or more, and even more preferably 0.0047 parts by mass or more, per part by mass of nickel in the feed. Also, the amount of iron compounds in the mixed solution, converted into iron, is preferably 0.12 parts by mass or less per part by mass of nickel in the feed, more preferably 0.08 parts by mass or less, even more preferably 0.06 parts by mass or less, even more preferably 0.030 parts by mass or less, and even more preferably 0.020 parts by mass or less, per part by mass of nickel in the feed.
金属元素Ｍがモリブデンである場合、ニッケル母粒子にニッケルとモリブデンとの合金を含む表面域を首尾よく形成させる観点から、混合液中におけるモリブデン化合物の量はモリブデンに換算して、仕込みの１質量部のニッケル量に対して、０．００４質量部以上とすることが好ましく、０．０１質量部以上とすることがより好ましく、０．０１３質量部以上とすることが更に好ましく、０．０１６質量部以上とすることが一層好ましい。また、混合液中におけるモリブデン化合物の量はモリブデンに換算して、仕込みの１質量部のニッケル量に対して、０．１２質量部以下とすることが好ましく、０．０７質量部以下とすることがより好ましく、０．０６質量部以下とすることが更に好ましく、０．０５１質量部以下とすることが一層好ましく、０．０３４質量部以下とすることが更に一層好ましい。
When the metal element M is molybdenum, from the viewpoint of successfully forming a surface region containing an alloy of nickel and molybdenum on the nickel mother particles, the amount of the molybdenum compound in the mixed solution, converted into molybdenum, is preferably 0.004 parts by mass or more per part by mass of nickel charged, more preferably 0.01 parts by mass or more, even more preferably 0.013 parts by mass or more, and even more preferably 0.016 parts by mass or more, per part by mass of nickel charged. Also, the amount of the molybdenum compound in the mixed solution, converted into molybdenum, is preferably 0.12 parts by mass or less per part by mass of nickel charged, more preferably 0.07 parts by mass or less, even more preferably 0.06 parts by mass or less, even more preferably 0.051 parts by mass or less, and even more preferably 0.034 parts by mass or less, per part by mass of nickel charged.
次に、以上の金属元素Ｍの化合物を含む混合液を撹拌しながら加熱して、前記混合液中の水酸化ニッケル及び該化合物の還元を行う。この還元反応によって、混合液中に残存していた水酸化ニッケルがニッケルに還元され、金属元素Ｍがビスマスである場合は金属元素Ｍの化合物はビスマスに還元される。あるいは、金属元素Ｍが銅である場合は金属元素Ｍの化合物は銅に還元される。あるいは、金属元素Ｍが鉄である場合は金属元素Ｍの化合物は鉄に還元される。あるいは、金属元素Ｍがモリブデンである場合は金属元素Ｍの化合物はモリブデンに還元される。この還元反応において、水酸化ニッケルと金属元素Ｍの化合物とを同時に還元させることで、ニッケル母粒子の表面に、ニッケル元素と金属Ｍとが均質に固溶したニッケル・金属Ｍ合金を含む表面域が形成される。なお、本発明の効果が奏される限りにおいて、金属元素Ｍの一部が金属元素Ｍの単体の状態、金属元素Ｍの化合物の状態、あるいはこれらを二種以上組み合わせた状態で存在することは許容される。
Next, the mixed solution containing the compound of the metal element M is heated while being stirred to reduce the nickel hydroxide and the compound in the mixed solution. This reduction reaction reduces the nickel hydroxide remaining in the mixed solution to nickel, and if the metal element M is bismuth, the compound of the metal element M is reduced to bismuth. Alternatively, if the metal element M is copper, the compound of the metal element M is reduced to copper. Alternatively, if the metal element M is iron, the compound of the metal element M is reduced to iron. Alternatively, if the metal element M is molybdenum, the compound of the metal element M is reduced to molybdenum. In this reduction reaction, the nickel hydroxide and the compound of the metal element M are simultaneously reduced, and a surface region containing a nickel-metal M alloy in which the nickel element and the metal M are homogeneously dissolved in solid solution is formed on the surface of the nickel mother particle. As long as the effect of the present invention is achieved, it is acceptable that a part of the metal element M exists in the state of the simple substance of the metal element M, in the state of a compound of the metal element M, or in a state in which two or more of these are combined.
前記の混合液の加熱温度は、使用するポリオールや金属元素Ｍの化合物の種類にもよるが、大気圧下において好ましくは１５０℃以上２００℃以下、更に好ましくは１７０℃以上２００℃以下、一層好ましくは１９０℃以上２００℃以下である。加熱温度をこの範囲内とすることによって、水酸化ニッケル及び金属元素Ｍの化合物を同時に還元させ、ニッケル母粒子の表面に、ニッケル・金属Ｍ合金を含む表面域を首尾よく形成させることができる。
The heating temperature of the mixture depends on the type of polyol and metal element M compound used, but is preferably 150°C to 200°C under atmospheric pressure, more preferably 170°C to 200°C, and even more preferably 190°C to 200°C. By keeping the heating temperature within this range, nickel hydroxide and the metal element M compound can be reduced simultaneously, and a surface region containing nickel-metal M alloy can be successfully formed on the surface of the nickel mother particles.
その後、必要に応じて、得られたニッケル粒子の分散液中のポリオールを水で置換し、次いで置換した水をメタノールで再置換して該ニッケル粒子を洗浄し、真空乾燥を行う。このようにして本発明のニッケル粒子を製造することができる。
Then, if necessary, the polyol in the resulting dispersion of nickel particles is replaced with water, and then the replaced water is replaced again with methanol to wash the nickel particles, followed by vacuum drying. In this manner, the nickel particles of the present invention can be produced.
金属元素Ｍを含むニッケル粒子を製造する場合、ニッケル原料に金属元素Ｍの原料を添加してＰＶＤ法又はＣＶＤ法を行うことができる。その場合のニッケル粒子はその全体にニッケル・金属Ｍ合金が形成されることになる。しかし、このニッケル粒子の耐焼結性を高めようとする場合、ニッケル粒子全体における金属元素Ｍであるビスマス、銅、鉄及び／又はモリブデンの含有量が過度に高くなり、その結果電気抵抗が高くなるという課題があった。このことに加えて、ニッケル粒子の粒径が不均一になることで、該ニッケル粒子を用いて導電膜を形成した際に導電膜の表面が粗いものとなり、ＭＬＣＣの内部電極間の短絡発生の原因の一つとなるという課題があった。また、金属元素Ｍを含むニッケル粒子を製造する別の方法として、特許文献２に記載されているとおり、水酸化ニッケルの全量を還元させた後に金属元素Ｍの化合物を添加する方法が知られている。この場合、金属元素Ｍとしてビスマス及び／又は銅を用いると、ニッケル粒子の表面にニッケルよりも融点が低いビスマス及び／又は銅の単体の層が形成される。しかし、このニッケル粒子の耐焼結性は、粒子の表面がビスマス及び／又は銅の単体の層からなることに起因して高いものとならなかった。また、金属元素Ｍとして鉄及び／又はモリブデンを用いる場合、単体の鉄及びモリブデンが容易に酸化しやすいことに起因して、ニッケル粒子の表面に鉄酸化物及び／又はモリブデン酸化物を含む層が形成される。このような層が形成されたニッケル粒子をＭＬＣＣの製造時に焼成した場合、該層に含まれる酸化物が誘電体層に吸収されてしまうので、該ニッケル粒子の耐焼結性も高いものとならなかった。これに対して、ニッケル母粒子とその表面に配置されたニッケル・金属Ｍ合金からなる本発明のニッケル粒子によれば、電気抵抗を過度に高めることなく耐焼結性を高くすることができる。更に、本発明のニッケル粒子を用いて導電膜を形成すると、該導電膜の表面を平滑なものとすることができる。これらの理由から、上述のとおり、一部の水酸化ニッケルが残存している状態で、該水酸化ニッケルと金属元素Ｍの化合物とを同時に還元させてニッケル粒子を製造することが好ましい。
When nickel particles containing metal element M are manufactured, a PVD method or CVD method can be performed by adding a raw material of metal element M to a nickel raw material. In that case, a nickel-metal M alloy is formed throughout the nickel particles. However, when trying to increase the sintering resistance of these nickel particles, the content of metal element M, bismuth, copper, iron and/or molybdenum, in the entire nickel particle becomes excessively high, resulting in a problem of high electrical resistance. In addition, there is a problem that the particle size of the nickel particles becomes uneven, and when a conductive film is formed using the nickel particles, the surface of the conductive film becomes rough, which is one of the causes of short circuits between the internal electrodes of the MLCC. In addition, as another method for manufacturing nickel particles containing metal element M, as described in Patent Document 2, a method is known in which a compound of metal element M is added after reducing the entire amount of nickel hydroxide. In this case, when bismuth and/or copper are used as metal element M, a layer of simple bismuth and/or copper, which has a lower melting point than nickel, is formed on the surface of the nickel particles. However, the sintering resistance of these nickel particles is not high due to the surface of the particles being made of a simple layer of bismuth and/or copper. In addition, when iron and/or molybdenum are used as the metal element M, a layer containing iron oxide and/or molybdenum oxide is formed on the surface of the nickel particles due to the fact that simple iron and molybdenum are easily oxidized. When nickel particles with such a layer are sintered during the manufacture of MLCC, the oxide contained in the layer is absorbed into the dielectric layer, and the sintering resistance of the nickel particles is not high. In contrast, the nickel particles of the present invention, which are made of nickel mother particles and a nickel-metal M alloy arranged on the surface thereof, can increase the sintering resistance without excessively increasing the electrical resistance. Furthermore, when a conductive film is formed using the nickel particles of the present invention, the surface of the conductive film can be made smooth. For these reasons, as described above, it is preferable to produce nickel particles by simultaneously reducing the nickel hydroxide and the compound of the metal element M while some of the nickel hydroxide remains.
以上の方法で製造されたニッケル粒子は、微粒且つ均一な粒径でありながら、該ニッケル粒子の表面にニッケル・金属Ｍ合金を含む表面域を有するという特徴を活かして様々な分野に用いられる。特にＭＬＣＣの内部電極の形成に好適に用いられる。
The nickel particles produced by the above method are used in a variety of fields, taking advantage of the fact that they have a fine, uniform particle size and a surface region containing nickel-metal M alloy on the surface of the nickel particles. They are particularly suitable for use in forming the internal electrodes of MLCCs.
以上、本発明をその好ましい実施形態に基づき説明したが、本発明は前記実施形態に制限されない。
The present invention has been described above based on a preferred embodiment, but the present invention is not limited to the above embodiment.
前記実施形態に関し、更に以下のニッケル粒子及びその製造方法を開示する。
〔１〕 ニッケルと金属元素Ｍとの合金を含む表面域を有するニッケル粒子であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種であり、
前記ニッケル粒子全体に対する前記金属元素Ｍの含有量が０．０９質量％以上１５．８質量％以下であり、
Ｘ線光電子分光分析によって前記ニッケル粒子の深さ方向において最表面からＳｉＯ２換算でのスパッタ深さ５ｎｍまでの領域を測定したときに、該領域において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の最大値をＸ（ａｔ％）とし、
ＩＣＰ発光分光分析法によって前記ニッケル粒子を測定したとき、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合をＹ（ａｔ％）としたとき、
Ｘ／Ｙの値が０．５以上３５以下である、ニッケル粒子。
〔２〕 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０としたとき、Ｄ５０が２０ｎｍ以上２００ｎｍ以下であり、
前記粒度分布における粒径の標準偏差をσ（ｎｍ）としたとき、変動係数（σ／Ｄ５０）（％）の値が１４％以下である、〔１〕に記載のニッケル粒子。
変動係数（％）＝（σ／Ｄ５０）×１００
〔３〕 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０としたとき、Ｄ５０の１．５倍以上の粒径を有する粒子の存在割合が０．５個数％以下である、〔１〕又は〔２〕に記載のニッケル粒子。
〔４〕 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０とし、ＷＰＰＦ法によって測定された結晶子サイズをＣｓ（ｎｍ）としたとき、Ｃｓ／Ｄ５０の値が０．３以上０．６以下である、〔１〕ないし〔３〕のいずれか一に記載のニッケル粒子。
〔５〕 水酸化ニッケル粒子、ポリオール、ポリビニルピロリドン及びポリエチレンイミンを含む混合液を加熱してニッケル粒子を製造する方法であって、
１質量部のポリエチレンイミンに対して、ポリビニルピロリドンを３０質量部以上２００質量部以下用い、
前記加熱によって前記水酸化ニッケル粒子をニッケル母粒子に還元し、
一部の前記水酸化ニッケル粒子が残存している状態で、前記混合液と金属元素Ｍの化合物とを混合し、該化合物を金属Ｍに還元して、前記ニッケル母粒子に、ニッケルと金属元素Ｍとの合金を含む表面域を形成する、ニッケル粒子の製造方法であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種である、ニッケル粒子の製造方法。
〔６〕 〔１〕ないし〔４〕のいずれか一に記載のニッケル粒子を内部電極に用いた、積層セラミックコンデンサ。 In relation to the above embodiment, the following nickel particles and a method for producing the same are further disclosed.
[1] A nickel particle having a surface region containing an alloy of nickel and a metal element M,
The metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
The content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
When a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy, the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%);
When the nickel particles are measured by ICP atomic emission spectrometry, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %),
Nickel particles having a value of X/Y of 0.5 or more and 35 or less.
[2] In a particle size distribution based on a circle equivalent diameter calculated from a measurement using a scanning electron microscope, when the number cumulative particle diameter at 50% by number of cumulative particles is defined as D50 , D50 is 20 nm or more and 200 nm or less;
The nickel particles according to [1], wherein when the standard deviation of particle diameters in the particle size distribution is σ (nm), the value of the coefficient of variation (σ/D 50 ) (%) is 14% or less.
Coefficient of variation (%) = (σ/D 50 ) × 100
[3] The nickel particles according to [1] or [2], in which, in a particle size distribution based on the circle equivalent diameter calculated from measurement using a scanning electron microscope, when the number cumulative particle size at 50% by number of cumulative particles is defined as D50 , the proportion of particles having a particle size 1.5 times or more of D50 is 0.5% by number or less.
[4] In a particle size distribution based on a circle equivalent diameter calculated from a measurement using a scanning electron microscope, when the number cumulative particle size at 50% of the cumulative number is defined as D50 and the crystallite size measured by the WPPF method is defined as Cs (nm), the value of Cs/ D50 is 0.3 or more and 0.6 or less. Nickel particles according to any one of [1] to [3].
[5] A method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of:
Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine,
The heating reduces the nickel hydroxide particles to nickel base particles,
A method for producing nickel particles, comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
The method for producing nickel particles, wherein the metal element M is at least one selected from bismuth, copper, iron and molybdenum.
[6] A multilayer ceramic capacitor using the nickel particles according to any one of [1] to [4] in an internal electrode.
〔１〕 ニッケルと金属元素Ｍとの合金を含む表面域を有するニッケル粒子であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種であり、
前記ニッケル粒子全体に対する前記金属元素Ｍの含有量が０．０９質量％以上１５．８質量％以下であり、
Ｘ線光電子分光分析によって前記ニッケル粒子の深さ方向において最表面からＳｉＯ２換算でのスパッタ深さ５ｎｍまでの領域を測定したときに、該領域において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の最大値をＸ（ａｔ％）とし、
ＩＣＰ発光分光分析法によって前記ニッケル粒子を測定したとき、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合をＹ（ａｔ％）としたとき、
Ｘ／Ｙの値が０．５以上３５以下である、ニッケル粒子。
〔２〕 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０としたとき、Ｄ５０が２０ｎｍ以上２００ｎｍ以下であり、
前記粒度分布における粒径の標準偏差をσ（ｎｍ）としたとき、変動係数（σ／Ｄ５０）（％）の値が１４％以下である、〔１〕に記載のニッケル粒子。
変動係数（％）＝（σ／Ｄ５０）×１００
〔３〕 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０としたとき、Ｄ５０の１．５倍以上の粒径を有する粒子の存在割合が０．５個数％以下である、〔１〕又は〔２〕に記載のニッケル粒子。
〔４〕 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０とし、ＷＰＰＦ法によって測定された結晶子サイズをＣｓ（ｎｍ）としたとき、Ｃｓ／Ｄ５０の値が０．３以上０．６以下である、〔１〕ないし〔３〕のいずれか一に記載のニッケル粒子。
〔５〕 水酸化ニッケル粒子、ポリオール、ポリビニルピロリドン及びポリエチレンイミンを含む混合液を加熱してニッケル粒子を製造する方法であって、
１質量部のポリエチレンイミンに対して、ポリビニルピロリドンを３０質量部以上２００質量部以下用い、
前記加熱によって前記水酸化ニッケル粒子をニッケル母粒子に還元し、
一部の前記水酸化ニッケル粒子が残存している状態で、前記混合液と金属元素Ｍの化合物とを混合し、該化合物を金属Ｍに還元して、前記ニッケル母粒子に、ニッケルと金属元素Ｍとの合金を含む表面域を形成する、ニッケル粒子の製造方法であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種である、ニッケル粒子の製造方法。
〔６〕 〔１〕ないし〔４〕のいずれか一に記載のニッケル粒子を内部電極に用いた、積層セラミックコンデンサ。 In relation to the above embodiment, the following nickel particles and a method for producing the same are further disclosed.
[1] A nickel particle having a surface region containing an alloy of nickel and a metal element M,
The metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
The content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
When a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy, the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%);
When the nickel particles are measured by ICP atomic emission spectrometry, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %),
Nickel particles having a value of X/Y of 0.5 or more and 35 or less.
[2] In a particle size distribution based on a circle equivalent diameter calculated from a measurement using a scanning electron microscope, when the number cumulative particle diameter at 50% by number of cumulative particles is defined as D50 , D50 is 20 nm or more and 200 nm or less;
The nickel particles according to [1], wherein when the standard deviation of particle diameters in the particle size distribution is σ (nm), the value of the coefficient of variation (σ/D 50 ) (%) is 14% or less.
Coefficient of variation (%) = (σ/D 50 ) × 100
[3] The nickel particles according to [1] or [2], in which, in a particle size distribution based on the circle equivalent diameter calculated from measurement using a scanning electron microscope, when the number cumulative particle size at 50% by number of cumulative particles is defined as D50 , the proportion of particles having a particle size 1.5 times or more of D50 is 0.5% by number or less.
[4] In a particle size distribution based on a circle equivalent diameter calculated from a measurement using a scanning electron microscope, when the number cumulative particle size at 50% of the cumulative number is defined as D50 and the crystallite size measured by the WPPF method is defined as Cs (nm), the value of Cs/ D50 is 0.3 or more and 0.6 or less. Nickel particles according to any one of [1] to [3].
[5] A method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of:
Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine,
The heating reduces the nickel hydroxide particles to nickel base particles,
A method for producing nickel particles, comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
The method for producing nickel particles, wherein the metal element M is at least one selected from bismuth, copper, iron and molybdenum.
[6] A multilayer ceramic capacitor using the nickel particles according to any one of [1] to [4] in an internal electrode.
以下、実施例により本発明を更に詳細に説明する。しかしながら本発明の範囲は、かかる実施例に制限されない。特に断らない限り、「％」は「質量％」を意味する。
The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, "%" means "% by mass."
〔実施例１〕
５００ｍｌのビーカーに、４４５ｇのエチレングリコール、６４ｇの水酸化ニッケル粒子、１２ｇのポリビニルピロリドン、０．１４ｇのポリエチレンイミン、及び０．１３ｍｌの硝酸パラジウム水溶液（濃度：１００ｇ／ｌ）を加えて混合液を調製した。ポリエチレンイミンは分岐鎖状のものであり、数平均分子量は１８００であった。混合液を撹拌しながら加熱し、大気圧下において１９８℃で５時間還元反応を行った。この時点で、水酸化ニッケルの還元は、仕込み量の水酸化ニッケルに対して８０ｍｏｌ％進行していた。次いで、その後、塩化ビスマスを０．３ｇ添加し、大気圧下において１９８℃で更に１０時間還元反応を行った。加熱を停止して還元を終了させ、室温まで自然放冷した。このようにして、多数のニッケル粒子を得た。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
次いで、メタノール５０ｇを加えて分散液を１０分間撹拌した。磁石を用いることによって上澄みの除去を３回繰り返し、分散液中の溶媒をメタノールに置換した。その後、８０℃で真空乾燥を行い、ニッケル粒子を得た。 Example 1
A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 12 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker. The polyethyleneimine was branched and had a number average molecular weight of 1800. The mixture was heated while stirring, and a reduction reaction was carried out at 198 ° C. under atmospheric pressure for 5 hours. At this point, the reduction of nickel hydroxide had progressed to 80 mol % with respect to the amount of nickel hydroxide charged. Then, 0.3 g of bismuth chloride was added, and a reduction reaction was carried out at 198 ° C. under atmospheric pressure for another 10 hours. The heating was stopped to terminate the reduction, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
A magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
Next, 50 g of methanol was added and the dispersion was stirred for 10 minutes. The supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain nickel particles.
５００ｍｌのビーカーに、４４５ｇのエチレングリコール、６４ｇの水酸化ニッケル粒子、１２ｇのポリビニルピロリドン、０．１４ｇのポリエチレンイミン、及び０．１３ｍｌの硝酸パラジウム水溶液（濃度：１００ｇ／ｌ）を加えて混合液を調製した。ポリエチレンイミンは分岐鎖状のものであり、数平均分子量は１８００であった。混合液を撹拌しながら加熱し、大気圧下において１９８℃で５時間還元反応を行った。この時点で、水酸化ニッケルの還元は、仕込み量の水酸化ニッケルに対して８０ｍｏｌ％進行していた。次いで、その後、塩化ビスマスを０．３ｇ添加し、大気圧下において１９８℃で更に１０時間還元反応を行った。加熱を停止して還元を終了させ、室温まで自然放冷した。このようにして、多数のニッケル粒子を得た。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
次いで、メタノール５０ｇを加えて分散液を１０分間撹拌した。磁石を用いることによって上澄みの除去を３回繰り返し、分散液中の溶媒をメタノールに置換した。その後、８０℃で真空乾燥を行い、ニッケル粒子を得た。 Example 1
A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 12 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker. The polyethyleneimine was branched and had a number average molecular weight of 1800. The mixture was heated while stirring, and a reduction reaction was carried out at 198 ° C. under atmospheric pressure for 5 hours. At this point, the reduction of nickel hydroxide had progressed to 80 mol % with respect to the amount of nickel hydroxide charged. Then, 0.3 g of bismuth chloride was added, and a reduction reaction was carried out at 198 ° C. under atmospheric pressure for another 10 hours. The heating was stopped to terminate the reduction, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
A magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
Next, 50 g of methanol was added and the dispersion was stirred for 10 minutes. The supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain nickel particles.
〔実施例２ないし６〕
硝酸パラジウム水溶液の添加量及び塩化ビスマスの添加量、並びに混合液の加熱を開始してから該混合液に塩化ビスマスを添加するまでの時間を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 [Examples 2 to 6]
The amount of the aqueous palladium nitrate solution and the amount of bismuth chloride added, as well as the time from the start of heating the mixed solution to the addition of bismuth chloride to the mixed solution, were as shown in Table 1. Other than these, nickel particles were obtained in the same manner as in Example 1.
硝酸パラジウム水溶液の添加量及び塩化ビスマスの添加量、並びに混合液の加熱を開始してから該混合液に塩化ビスマスを添加するまでの時間を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 [Examples 2 to 6]
The amount of the aqueous palladium nitrate solution and the amount of bismuth chloride added, as well as the time from the start of heating the mixed solution to the addition of bismuth chloride to the mixed solution, were as shown in Table 1. Other than these, nickel particles were obtained in the same manner as in Example 1.
〔実施例７〕
塩化ビスマスに代えて硫酸銅５水和物を添加した。硝酸パラジウム水溶液の添加量及び硫酸銅５水和物の添加量を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 Example 7
Copper sulfate pentahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the copper sulfate pentahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
塩化ビスマスに代えて硫酸銅５水和物を添加した。硝酸パラジウム水溶液の添加量及び硫酸銅５水和物の添加量を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 Example 7
Copper sulfate pentahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the copper sulfate pentahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
〔実施例８〕
塩化ビスマスに代えて硫酸鉄７水和物を添加した。硝酸パラジウム水溶液の添加量及び硫酸鉄７水和物の添加量を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 Example 8
Iron sulfate heptahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the iron sulfate heptahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
塩化ビスマスに代えて硫酸鉄７水和物を添加した。硝酸パラジウム水溶液の添加量及び硫酸鉄７水和物の添加量を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 Example 8
Iron sulfate heptahydrate was added in place of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the iron sulfate heptahydrate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
〔実施例９〕
塩化ビスマスに代えてモリブデン酸ナトリウムを添加した。硝酸パラジウム水溶液の添加量及びモリブデン酸ナトリウムの添加量を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 Example 9
Sodium molybdate was added instead of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the sodium molybdate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
塩化ビスマスに代えてモリブデン酸ナトリウムを添加した。硝酸パラジウム水溶液の添加量及びモリブデン酸ナトリウムの添加量を表１に示すとおりとした。これら以外は実施例１と同様にしてニッケル粒子を得た。 Example 9
Sodium molybdate was added instead of bismuth chloride. The amounts of the aqueous palladium nitrate solution and the sodium molybdate added were as shown in Table 1. Nickel particles were obtained in the same manner as in Example 1 except for the above.
〔比較例１〕
５００ｍｌのビーカーに、４４５ｇのエチレングリコール、６４ｇの水酸化ニッケル粒子、８ｇのポリビニルピロリドン、０．１４ｇのポリエチレンイミン、及び０．１３ｍｌの硝酸パラジウム水溶液（濃度：１００ｇ／ｌ）を加えて混合液を調製した。ポリエチレンイミンは分岐鎖状のものであり、数平均分子量は１８００であった。混合液を撹拌しながら加熱し、１９８℃で６．５時間還元反応を行った。加熱を停止して還元を終了させ、室温まで自然放冷した。このようにして、多数のニッケル粒子を得た。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
次いで、メタノール５０ｇを加えて分散液を１０分間撹拌した。磁石を用いることによって上澄みの除去を３回繰り返し、分散液中の溶媒をメタノールに置換した。その後、８０℃で真空乾燥を行い、ニッケル粒子の粉末を得た。 Comparative Example 1
A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker. The polyethyleneimine was branched and had a number average molecular weight of 1800. The mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
A magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
Next, 50 g of methanol was added and the dispersion was stirred for 10 minutes. The supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain a powder of nickel particles.
５００ｍｌのビーカーに、４４５ｇのエチレングリコール、６４ｇの水酸化ニッケル粒子、８ｇのポリビニルピロリドン、０．１４ｇのポリエチレンイミン、及び０．１３ｍｌの硝酸パラジウム水溶液（濃度：１００ｇ／ｌ）を加えて混合液を調製した。ポリエチレンイミンは分岐鎖状のものであり、数平均分子量は１８００であった。混合液を撹拌しながら加熱し、１９８℃で６．５時間還元反応を行った。加熱を停止して還元を終了させ、室温まで自然放冷した。このようにして、多数のニッケル粒子を得た。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
次いで、メタノール５０ｇを加えて分散液を１０分間撹拌した。磁石を用いることによって上澄みの除去を３回繰り返し、分散液中の溶媒をメタノールに置換した。その後、８０℃で真空乾燥を行い、ニッケル粒子の粉末を得た。 Comparative Example 1
A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker. The polyethyleneimine was branched and had a number average molecular weight of 1800. The mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
A magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
Next, 50 g of methanol was added and the dispersion was stirred for 10 minutes. The supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. After that, the dispersion was vacuum dried at 80° C. to obtain a powder of nickel particles.
〔比較例２〕
水酸化ニッケルの還元反応を行う前に塩化ビスマスを添加した以外は、実施例１と同様にしてニッケル粒子を得た。 Comparative Example 2
Nickel particles were obtained in the same manner as in Example 1, except that bismuth chloride was added before carrying out the reduction reaction of nickel hydroxide.
水酸化ニッケルの還元反応を行う前に塩化ビスマスを添加した以外は、実施例１と同様にしてニッケル粒子を得た。 Comparative Example 2
Nickel particles were obtained in the same manner as in Example 1, except that bismuth chloride was added before carrying out the reduction reaction of nickel hydroxide.
〔比較例３〕
５００ｍｌのビーカーに、４４５ｇのエチレングリコール、６４ｇの水酸化ニッケル粒子、８ｇのポリビニルピロリドン、０．１４ｇのポリエチレンイミン、及び０．１３ｍｌの硝酸パラジウム水溶液（濃度：１００ｇ／ｌ）を加えて混合液を調製した。ポリエチレンイミンは分岐鎖状のものであり、数平均分子量は１８００であった。混合液を撹拌しながら加熱し、１９８℃で６．５時間還元反応を行った。加熱を停止して還元を終了させ、室温まで自然放冷した。このようにして、多数のニッケル粒子を得た。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
この分散液に、純水３００ｇ及びヒドラジン１水和物を加えて６０℃に昇温後、スズ酸ナトリウム３水和物を１ｇ添加し、５時間撹拌を行い、スズによる表面処理をニッケル粒子に施した。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して、該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
次いで、メタノール５０ｇを加えて分散液を１０分間撹拌した。磁石を用いることによって上澄みの除去を３回繰り返し、分散液中の溶媒をメタノールに置換した。その後、８０℃で真空乾燥を行い、スズによる表面処理が施されたニッケル粒子の粉末を得た。ニッケル粒子の表面域はニッケルとスズとの合金を含まず、スズ表面層が形成されていることを後述の〔評価１〕に記載のとおり確認した。 Comparative Example 3
A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker. The polyethyleneimine was branched and had a number average molecular weight of 1800. The mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
A magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
To this dispersion, 300 g of pure water and hydrazine monohydrate were added and the temperature was raised to 60° C., after which 1 g of sodium stannate trihydrate was added and the mixture was stirred for 5 hours to subject the nickel particles to a surface treatment with tin.
A magnet was placed at the bottom of a beaker containing the obtained dispersion of nickel particles, and the nickel particles were attracted to the magnet. Under this condition, the supernatant of the dispersion was removed.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
Next, 50 g of methanol was added and the dispersion was stirred for 10 minutes. The supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. Then, the mixture was vacuum dried at 80° C. to obtain a powder of nickel particles that had been surface-treated with tin. It was confirmed that the surface region of the nickel particles did not contain an alloy of nickel and tin, and that a tin surface layer was formed, as described in [Evaluation 1] below.
５００ｍｌのビーカーに、４４５ｇのエチレングリコール、６４ｇの水酸化ニッケル粒子、８ｇのポリビニルピロリドン、０．１４ｇのポリエチレンイミン、及び０．１３ｍｌの硝酸パラジウム水溶液（濃度：１００ｇ／ｌ）を加えて混合液を調製した。ポリエチレンイミンは分岐鎖状のものであり、数平均分子量は１８００であった。混合液を撹拌しながら加熱し、１９８℃で６．５時間還元反応を行った。加熱を停止して還元を終了させ、室温まで自然放冷した。このようにして、多数のニッケル粒子を得た。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
この分散液に、純水３００ｇ及びヒドラジン１水和物を加えて６０℃に昇温後、スズ酸ナトリウム３水和物を１ｇ添加し、５時間撹拌を行い、スズによる表面処理をニッケル粒子に施した。
得られたニッケル粒子の分散液を含むビーカーの底に磁石を配置して、該ニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。
ビーカーの底から磁石を取り除いた後、純水５０ｇを加えて分散液を１０分間撹拌した。その後、ビーカーの底に磁石を再び配置してニッケル粒子を磁石に引き寄せた。この状態下に、前記分散液の上澄みを除去した。一連の操作を５回繰り返した。
次いで、メタノール５０ｇを加えて分散液を１０分間撹拌した。磁石を用いることによって上澄みの除去を３回繰り返し、分散液中の溶媒をメタノールに置換した。その後、８０℃で真空乾燥を行い、スズによる表面処理が施されたニッケル粒子の粉末を得た。ニッケル粒子の表面域はニッケルとスズとの合金を含まず、スズ表面層が形成されていることを後述の〔評価１〕に記載のとおり確認した。 Comparative Example 3
A mixture was prepared by adding 445 g of ethylene glycol, 64 g of nickel hydroxide particles, 8 g of polyvinylpyrrolidone, 0.14 g of polyethyleneimine, and 0.13 ml of an aqueous palladium nitrate solution (concentration: 100 g/l) to a 500 ml beaker. The polyethyleneimine was branched and had a number average molecular weight of 1800. The mixture was heated with stirring and reduced at 198°C for 6.5 hours. The reduction was terminated by stopping the heating, and the mixture was allowed to cool naturally to room temperature. In this way, a large number of nickel particles were obtained.
A magnet was placed at the bottom of a beaker containing the resulting nickel particle dispersion to attract the nickel particles to the magnet, and the supernatant of the dispersion was removed under this condition.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
To this dispersion, 300 g of pure water and hydrazine monohydrate were added and the temperature was raised to 60° C., after which 1 g of sodium stannate trihydrate was added and the mixture was stirred for 5 hours to subject the nickel particles to a surface treatment with tin.
A magnet was placed at the bottom of a beaker containing the obtained dispersion of nickel particles, and the nickel particles were attracted to the magnet. Under this condition, the supernatant of the dispersion was removed.
After removing the magnet from the bottom of the beaker, 50 g of pure water was added and the dispersion was stirred for 10 minutes. Then, the magnet was placed again at the bottom of the beaker to attract the nickel particles to the magnet. Under this condition, the supernatant of the dispersion was removed. The series of operations was repeated five times.
Next, 50 g of methanol was added and the dispersion was stirred for 10 minutes. The supernatant was removed three times using a magnet, and the solvent in the dispersion was replaced with methanol. Then, the mixture was vacuum dried at 80° C. to obtain a powder of nickel particles that had been surface-treated with tin. It was confirmed that the surface region of the nickel particles did not contain an alloy of nickel and tin, and that a tin surface layer was formed, as described in [Evaluation 1] below.
〔評価１〕
実施例１ないし９及び比較例１ないし３で得られたニッケル粒子について、以下のＸＰＳ分析方法でＸの値及びＸ１の値を求めた。
また、ＩＣＰ発光分光分析法によってニッケル粒子全体に対するビスマス元素、銅元素、鉄元素及びモリブデン元素の含有量及びＹの値を求めた。
また、上述の方法で粒度分布を測定し、粒径Ｄ５０、粗大粒子存在割合及び変動係数を求めた。
また、以下の方法でＷＰＰＦ法に基づくニッケルのａ軸長及び結晶子サイズＣｓを求めた。
また、上述の方法でニッケル粒子の表面域にニッケルとビスマスとの合金を含むか否か、ニッケルと銅との合金を含むか否か、ニッケルと鉄との合金を含むか否か、またニッケルとモリブデンとの合金を含むか否かを確認した。 [Evaluation 1]
For the nickel particles obtained in Examples 1 to 9 and Comparative Examples 1 to 3, the values of X and X1 were determined by the following XPS analysis method.
In addition, the contents of bismuth, copper, iron and molybdenum in the entire nickel particles and the value of Y were determined by ICP emission spectrometry.
Furthermore, the particle size distribution was measured by the above-mentioned method, and the particle size D 50 , the proportion of coarse particles, and the coefficient of variation were determined.
In addition, the a-axis length and crystallite size Cs of nickel based on the WPPF method were determined by the following method.
In addition, using the method described above, it was confirmed whether the surface region of the nickel particles contained an alloy of nickel and bismuth, an alloy of nickel and copper, an alloy of nickel and iron, or an alloy of nickel and molybdenum.
実施例１ないし９及び比較例１ないし３で得られたニッケル粒子について、以下のＸＰＳ分析方法でＸの値及びＸ１の値を求めた。
また、ＩＣＰ発光分光分析法によってニッケル粒子全体に対するビスマス元素、銅元素、鉄元素及びモリブデン元素の含有量及びＹの値を求めた。
また、上述の方法で粒度分布を測定し、粒径Ｄ５０、粗大粒子存在割合及び変動係数を求めた。
また、以下の方法でＷＰＰＦ法に基づくニッケルのａ軸長及び結晶子サイズＣｓを求めた。
また、上述の方法でニッケル粒子の表面域にニッケルとビスマスとの合金を含むか否か、ニッケルと銅との合金を含むか否か、ニッケルと鉄との合金を含むか否か、またニッケルとモリブデンとの合金を含むか否かを確認した。 [Evaluation 1]
For the nickel particles obtained in Examples 1 to 9 and Comparative Examples 1 to 3, the values of X and X1 were determined by the following XPS analysis method.
In addition, the contents of bismuth, copper, iron and molybdenum in the entire nickel particles and the value of Y were determined by ICP emission spectrometry.
Furthermore, the particle size distribution was measured by the above-mentioned method, and the particle size D 50 , the proportion of coarse particles, and the coefficient of variation were determined.
In addition, the a-axis length and crystallite size Cs of nickel based on the WPPF method were determined by the following method.
In addition, using the method described above, it was confirmed whether the surface region of the nickel particles contained an alloy of nickel and bismuth, an alloy of nickel and copper, an alloy of nickel and iron, or an alloy of nickel and molybdenum.
〔Ｘ線光電子分光分析（ＸＰＳ）測定〕
ＸＰＳ用の測定対象試料には、プレス機を用いてニッケル粒子をペレット状に成形したものを用いた。詳細には、φ５．２ｍｍ及び高さ２．５ｍｍの寸法を有するアルミニウム製容器に粒子試料を１０ｍｇ程度入れた。次いで、プレス機（アズワン製、品番：１－３１２－０１）及びアダプター（品番：１－３１２－０３）を用い、所定のストローク（２５ｍｍ）でアルミニウム製容器とともに加圧した。次いで、アルミニウム製容器に支持されたニッケル粒子のペレット成形物を取り出した。
得られたペレット成形物について、最表面測定及びＡｒモノマーイオンでのスパッタリングによる試料表面から内部に向かっての深さ方向測定を行った。測定条件は以下のとおりである。 [X-ray photoelectron spectroscopy (XPS) measurement]
The sample to be measured for XPS was made by molding nickel particles into pellets using a press. In detail, about 10 mg of the particle sample was placed in an aluminum container having dimensions of φ5.2 mm and height 2.5 mm. Then, using a press (manufactured by AS ONE, product number: 1-312-01) and an adapter (product number: 1-312-03), pressure was applied together with the aluminum container at a predetermined stroke (25 mm). The nickel particle pellets supported by the aluminum container were then removed.
The obtained pellet molded product was subjected to surface measurement and depth measurement from the sample surface to the inside by sputtering with Ar monomer ions. The measurement conditions were as follows.
ＸＰＳ用の測定対象試料には、プレス機を用いてニッケル粒子をペレット状に成形したものを用いた。詳細には、φ５．２ｍｍ及び高さ２．５ｍｍの寸法を有するアルミニウム製容器に粒子試料を１０ｍｇ程度入れた。次いで、プレス機（アズワン製、品番：１－３１２－０１）及びアダプター（品番：１－３１２－０３）を用い、所定のストローク（２５ｍｍ）でアルミニウム製容器とともに加圧した。次いで、アルミニウム製容器に支持されたニッケル粒子のペレット成形物を取り出した。
得られたペレット成形物について、最表面測定及びＡｒモノマーイオンでのスパッタリングによる試料表面から内部に向かっての深さ方向測定を行った。測定条件は以下のとおりである。 [X-ray photoelectron spectroscopy (XPS) measurement]
The sample to be measured for XPS was made by molding nickel particles into pellets using a press. In detail, about 10 mg of the particle sample was placed in an aluminum container having dimensions of φ5.2 mm and height 2.5 mm. Then, using a press (manufactured by AS ONE, product number: 1-312-01) and an adapter (product number: 1-312-03), pressure was applied together with the aluminum container at a predetermined stroke (25 mm). The nickel particle pellets supported by the aluminum container were then removed.
The obtained pellet molded product was subjected to surface measurement and depth measurement from the sample surface to the inside by sputtering with Ar monomer ions. The measurement conditions were as follows.
・測定装置：アルバック・ファイ株式会社製 ＶｅｒｓａＰｒｏｂｅＩＩＩ
・励起Ｘ線：単色化Ａｌ－Ｋα線（１４８６．７ｅＶ）
・出力：５０Ｗ
・加速電圧：１５ｋＶ
・Ｘ線照射径：２００μｍφ
・Ｘ線走査面積：１０００μｍ×３００μｍ
・検出角度：４５°
・パスエネルギー：２６．０ｅＶ
・エネルギーステップ：０．１ｅＶ／ｓｔｅｐ
・スパッタイオン種：Ａｒモノマーイオン
・スパッタレート：３．３ｎｍ／ｍｉｎ（ＳｉＯ２換算）
・スパッタ間隔：２０ｓ
・測定元素：Ｃ１ｓ、Ｎｉ２ｐ３、Ｓｎ３ｄ５、Ｂｉ４ｆ、Ｃｕ２ｐ、Ｆｅ３ｐ、Ｍｏ３ｄ
・エネルギー補正値：Ｃ１ｓにおけるＣ－Ｃ結合及びＣ－Ｈ結合（２８４．８ｅＶ） Measurement device: VersaProbeIII manufactured by ULVAC-PHI, Inc.
Excitation X-ray: Monochromatic Al-Kα ray (1486.7 eV)
Output: 50W
Acceleration voltage: 15 kV
・X-ray irradiation diameter: 200 μmφ
・X-ray scanning area: 1000 μm × 300 μm
Detection angle: 45°
Pass energy: 26.0 eV
Energy step: 0.1 eV/step
Sputter ion species: Ar monomer ions Sputter rate: 3.3 nm/min ( SiO2 equivalent)
Sputtering interval: 20 s
Measurement elements: C 1s , Ni 2p3 , Sn 3d5 , Bi 4f , Cu 2p , Fe 3p , Mo 3d
Energy correction value: C—C bond and C—H bond in C 1s (284.8 eV)
・励起Ｘ線：単色化Ａｌ－Ｋα線（１４８６．７ｅＶ）
・出力：５０Ｗ
・加速電圧：１５ｋＶ
・Ｘ線照射径：２００μｍφ
・Ｘ線走査面積：１０００μｍ×３００μｍ
・検出角度：４５°
・パスエネルギー：２６．０ｅＶ
・エネルギーステップ：０．１ｅＶ／ｓｔｅｐ
・スパッタイオン種：Ａｒモノマーイオン
・スパッタレート：３．３ｎｍ／ｍｉｎ（ＳｉＯ２換算）
・スパッタ間隔：２０ｓ
・測定元素：Ｃ１ｓ、Ｎｉ２ｐ３、Ｓｎ３ｄ５、Ｂｉ４ｆ、Ｃｕ２ｐ、Ｆｅ３ｐ、Ｍｏ３ｄ
・エネルギー補正値：Ｃ１ｓにおけるＣ－Ｃ結合及びＣ－Ｈ結合（２８４．８ｅＶ） Measurement device: VersaProbeIII manufactured by ULVAC-PHI, Inc.
Excitation X-ray: Monochromatic Al-Kα ray (1486.7 eV)
Output: 50W
Acceleration voltage: 15 kV
・X-ray irradiation diameter: 200 μmφ
・X-ray scanning area: 1000 μm × 300 μm
Detection angle: 45°
Pass energy: 26.0 eV
Energy step: 0.1 eV/step
Sputter ion species: Ar monomer ions Sputter rate: 3.3 nm/min ( SiO2 equivalent)
Sputtering interval: 20 s
Measurement elements: C 1s , Ni 2p3 , Sn 3d5 , Bi 4f , Cu 2p , Fe 3p , Mo 3d
Energy correction value: C—C bond and C—H bond in C 1s (284.8 eV)
〔ＸＰＳデータの解析〕
データ解析ソフトウェア（アルバック・ファイ社製「マルチパックＶｅｒ９．９」）を用いてＸＰＳデータの解析を行った。バックグラウンドモードはＳｈｉｒｌｅｙを使用した。 [Analysis of XPS Data]
The XPS data was analyzed using data analysis software (ULVAC-PHI, Inc., "Multipack Ver. 9.9"), with Shirley used as the background mode.
データ解析ソフトウェア（アルバック・ファイ社製「マルチパックＶｅｒ９．９」）を用いてＸＰＳデータの解析を行った。バックグラウンドモードはＳｈｉｒｌｅｙを使用した。 [Analysis of XPS Data]
The XPS data was analyzed using data analysis software (ULVAC-PHI, Inc., "Multipack Ver. 9.9"), with Shirley used as the background mode.
〔Ｘの値〕
実施例１ないし６では、Ｎｉ２ｐ３とＢｉ４ｆの計２元素の合計原子数に対するＢｉ４ｆの原子数の割合をＸ（ａｔ％）とした。実施例７では、Ｎｉ２ｐ３とＣｕ２ｐの計２元素の合計原子数に対するＣｕ２ｐの原子数の割合をＸ（ａｔ％）とした。実施例８では、Ｎｉ２ｐ３とＦｅ３ｐの計２元素の合計原子数に対するＦｅ３ｐの原子数の割合をＸ（ａｔ％）とした。実施例９では、Ｎｉ２ｐ３とＭｏ３ｄの計２元素の合計原子数に対するＭｏ３ｄの原子数の割合をＸ（ａｔ％）とした。 [Value of X]
In Examples 1 to 6, the ratio of the number of Bi 4f atoms to the total number of atoms of the two elements Ni 2p3 and Bi 4f was set to X (at%). In Example 7, the ratio of the number of Cu 2p atoms to the total number of atoms of the two elements Ni 2p3 and Cu 2p was set to X (at%). In Example 8, the ratio of the number of Fe 3p atoms to the total number of atoms of the two elements Ni 2p3 and Fe 3p was set to X (at%). In Example 9, the ratio of the number of Mo 3d atoms to the total number of atoms of the two elements Ni 2p3 and Mo 3d was set to X (at%).
実施例１ないし６では、Ｎｉ２ｐ３とＢｉ４ｆの計２元素の合計原子数に対するＢｉ４ｆの原子数の割合をＸ（ａｔ％）とした。実施例７では、Ｎｉ２ｐ３とＣｕ２ｐの計２元素の合計原子数に対するＣｕ２ｐの原子数の割合をＸ（ａｔ％）とした。実施例８では、Ｎｉ２ｐ３とＦｅ３ｐの計２元素の合計原子数に対するＦｅ３ｐの原子数の割合をＸ（ａｔ％）とした。実施例９では、Ｎｉ２ｐ３とＭｏ３ｄの計２元素の合計原子数に対するＭｏ３ｄの原子数の割合をＸ（ａｔ％）とした。 [Value of X]
In Examples 1 to 6, the ratio of the number of Bi 4f atoms to the total number of atoms of the two elements Ni 2p3 and Bi 4f was set to X (at%). In Example 7, the ratio of the number of Cu 2p atoms to the total number of atoms of the two elements Ni 2p3 and Cu 2p was set to X (at%). In Example 8, the ratio of the number of Fe 3p atoms to the total number of atoms of the two elements Ni 2p3 and Fe 3p was set to X (at%). In Example 9, the ratio of the number of Mo 3d atoms to the total number of atoms of the two elements Ni 2p3 and Mo 3d was set to X (at%).
〔ａ軸長及び結晶子サイズＣｓの測定〕
実施例及び比較例で得られたニッケル粒子のａ軸長及び結晶子サイズＣｓを、Ｘ線回折測定によって得られるニッケルに由来する回折ピークから、ＷＰＰＦ法を用いて算出した。 [Measurement of a-axis length and crystallite size Cs]
The a-axis length and crystallite size Cs of the nickel particles obtained in the examples and comparative examples were calculated using the WPPF method from the diffraction peaks derived from nickel obtained by X-ray diffraction measurement.
実施例及び比較例で得られたニッケル粒子のａ軸長及び結晶子サイズＣｓを、Ｘ線回折測定によって得られるニッケルに由来する回折ピークから、ＷＰＰＦ法を用いて算出した。 [Measurement of a-axis length and crystallite size Cs]
The a-axis length and crystallite size Cs of the nickel particles obtained in the examples and comparative examples were calculated using the WPPF method from the diffraction peaks derived from nickel obtained by X-ray diffraction measurement.
装置名 ＳｍａｒｔＬａｂ（９ＫＷ）：リガク社製
＜装置構成＞
波長
・ターゲット：Ｃｕ
・波長タイプ：Ｋα１
・Ｋα１：１．５４０５９（Å）
・Ｋα２：１．５４４４１（Å）
・Ｋβ：１．３９２２５（Å）
・Ｋα１２強度比：０．４９７０
・水平偏光率：０．５００
回折装置
・ゴニオメーター：ＳｍａｒｔＬａｂ
・アタッチメントベース：Ｚステージ単独
・アタッチメント：ＡＳＣ６－反射
＜測定条件＞
・光学系属性：集中法
・ＣＢＯ選択スリット：ＢＢ
・入射平行スリット：Ｓｏｌｌｅｒ＿ｓｌｉｔ＿５．０ｄｅｇ
・入射スリット：２／３ｄｅｇ
・長手制限スリット：１０．０ｍｍ
・受光スリット１：２０．０００ｍｍ
・受光平行スリット：Ｓｏｌｌｅｒ＿ｓｌｉｔ＿５．０ｄｅｇ
・受光スリット２：２０．０００ｍｍ
・アッテネーター：Ｏｐｅｎ
・検出器：Ｄ／ｔｅＸ Ｕｌｔｒａ２５０
・スキャン軸：２θ／θ
・スキャンモード：連続
・スキャン範囲：５．００００～１４０．００００ｄｅｇ
・ステップ幅：０．０１００ｄｅｇ
・スキャンスピード／計測時間：２．０１５５７２ｄｅｇ／ｍｉｎ
・データ点数：１３５０１点
・管電圧：４５ｋＶ
・管電流：２００ｍＡ
・ＨＶ：０．００ Device name: SmartLab (9KW): manufactured by Rigaku Corporation <Device configuration>
Wavelength Target: Cu
Wavelength type: Kα1
Kα1: 1.54059 (Å)
Kα2: 1.54441 (Å)
Kβ: 1.39225 (Å)
Kα12 intensity ratio: 0.4970
Horizontal polarization ratio: 0.500
Diffraction equipment/goniometer: SmartLab
・Attachment base: Z stage only ・Attachment: ASC6-reflection <Measurement conditions>
・Optical system attribute: Focusing method ・CBO selection slit: BB
・Inlet parallel slit: Soller_slit_5.0deg
Entrance slit: 2/3 deg
-Longitudinal limit slit: 10.0 mm
・Receiving slit 1: 20.000 mm
・ Receiving parallel slit: Soller_slit_5.0deg
・Receiving slit 2: 20.000 mm
Attenuator: Open
Detector: D/teX Ultra 250
Scan axis: 2θ/θ
・Scan mode: Continuous ・Scan range: 5.0000 to 140.0000 deg
Step width: 0.0100 deg
Scan speed/measurement time: 2.015572 deg/min
・Number of data points: 13,501 points ・Tube voltage: 45 kV
Tube current: 200mA
・HV: 0.00
＜装置構成＞
波長
・ターゲット：Ｃｕ
・波長タイプ：Ｋα１
・Ｋα１：１．５４０５９（Å）
・Ｋα２：１．５４４４１（Å）
・Ｋβ：１．３９２２５（Å）
・Ｋα１２強度比：０．４９７０
・水平偏光率：０．５００
回折装置
・ゴニオメーター：ＳｍａｒｔＬａｂ
・アタッチメントベース：Ｚステージ単独
・アタッチメント：ＡＳＣ６－反射
＜測定条件＞
・光学系属性：集中法
・ＣＢＯ選択スリット：ＢＢ
・入射平行スリット：Ｓｏｌｌｅｒ＿ｓｌｉｔ＿５．０ｄｅｇ
・入射スリット：２／３ｄｅｇ
・長手制限スリット：１０．０ｍｍ
・受光スリット１：２０．０００ｍｍ
・受光平行スリット：Ｓｏｌｌｅｒ＿ｓｌｉｔ＿５．０ｄｅｇ
・受光スリット２：２０．０００ｍｍ
・アッテネーター：Ｏｐｅｎ
・検出器：Ｄ／ｔｅＸ Ｕｌｔｒａ２５０
・スキャン軸：２θ／θ
・スキャンモード：連続
・スキャン範囲：５．００００～１４０．００００ｄｅｇ
・ステップ幅：０．０１００ｄｅｇ
・スキャンスピード／計測時間：２．０１５５７２ｄｅｇ／ｍｉｎ
・データ点数：１３５０１点
・管電圧：４５ｋＶ
・管電流：２００ｍＡ
・ＨＶ：０．００ Device name: SmartLab (9KW): manufactured by Rigaku Corporation <Device configuration>
Wavelength Target: Cu
Wavelength type: Kα1
Kα1: 1.54059 (Å)
Kα2: 1.54441 (Å)
Kβ: 1.39225 (Å)
Kα12 intensity ratio: 0.4970
Horizontal polarization ratio: 0.500
Diffraction equipment/goniometer: SmartLab
・Attachment base: Z stage only ・Attachment: ASC6-reflection <Measurement conditions>
・Optical system attribute: Focusing method ・CBO selection slit: BB
・Inlet parallel slit: Soller_slit_5.0deg
Entrance slit: 2/3 deg
-Longitudinal limit slit: 10.0 mm
・Receiving slit 1: 20.000 mm
・ Receiving parallel slit: Soller_slit_5.0deg
・Receiving slit 2: 20.000 mm
Attenuator: Open
Detector: D/teX Ultra 250
Scan axis: 2θ/θ
・Scan mode: Continuous ・Scan range: 5.0000 to 140.0000 deg
Step width: 0.0100 deg
Scan speed/measurement time: 2.015572 deg/min
・Number of data points: 13,501 points ・Tube voltage: 45 kV
Tube current: 200mA
・HV: 0.00
＜Ｘ線回折用試料の調製＞
測定対象のニッケル粒子を測定ホルダに敷き詰め、ニッケル粒子からなる層の厚さが０．５ｍｍで、且つ測定表面が平滑となるように、ガラスプレートを用いて平滑化した。 <Preparation of samples for X-ray diffraction>
The nickel particles to be measured were spread over a measurement holder, and the holder was smoothed using a glass plate so that the layer of nickel particles had a thickness of 0.5 mm and the measurement surface was smooth.
測定対象のニッケル粒子を測定ホルダに敷き詰め、ニッケル粒子からなる層の厚さが０．５ｍｍで、且つ測定表面が平滑となるように、ガラスプレートを用いて平滑化した。 <Preparation of samples for X-ray diffraction>
The nickel particles to be measured were spread over a measurement holder, and the holder was smoothed using a glass plate so that the layer of nickel particles had a thickness of 0.5 mm and the measurement surface was smooth.
上述の測定条件にて得られたＸ線回折パターンを用いて、以下の条件にて、解析用ソフトウェアによって解析した。解析では、米国国立標準技術局（ＮＩＳＴ）が提供する標準物質である六ホウ化ランタン粉末（ＳＲＭ６６０シリーズ）から得られたデータを用いて補正した。ａ軸長及び結晶子サイズＣｓは、ＷＰＰＦ法を用いて算出した。
The X-ray diffraction pattern obtained under the above measurement conditions was analyzed using analysis software under the following conditions. The analysis was corrected using data obtained from lanthanum hexaboride powder (SRM660 series), a standard material provided by the National Institute of Standards and Technology (NIST). The a-axis length and crystallite size Cs were calculated using the WPPF method.
＜測定データ解析条件＞
・解析用ソフトウェア：Ｒｉｇａｋｕ製ＰＤＸＬ２
・解析手法：ＷＰＰＦ法
・データ処理：自動プロファイル処理
（リガク社 ＰＤＸＬユーザーマニュアル ｐ．３０５） <Measurement data analysis conditions>
Analysis software: Rigaku PDXL2
- Analysis method: WPPF method - Data processing: Automatic profile processing (Rigaku PDXL User Manual p.305)
・解析用ソフトウェア：Ｒｉｇａｋｕ製ＰＤＸＬ２
・解析手法：ＷＰＰＦ法
・データ処理：自動プロファイル処理
（リガク社 ＰＤＸＬユーザーマニュアル ｐ．３０５） <Measurement data analysis conditions>
Analysis software: Rigaku PDXL2
- Analysis method: WPPF method - Data processing: Automatic profile processing (Rigaku PDXL User Manual p.305)
〔評価２〕
実施例１ないし９及び比較例１ないし３で得られたニッケル粒子について、以下の方法で、ニッケル粒子の収縮開始温度、ニッケル粒子を含む焼結膜の比抵抗及び表面粗さＲｚを測定した。以上の結果を以下の表１に示す。 [Evaluation 2]
The nickel particles obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were measured for the shrinkage starting temperature of the nickel particles, the resistivity and the surface roughness Rz of the sintered film containing the nickel particles by the following methods. The results are shown in Table 1 below.
実施例１ないし９及び比較例１ないし３で得られたニッケル粒子について、以下の方法で、ニッケル粒子の収縮開始温度、ニッケル粒子を含む焼結膜の比抵抗及び表面粗さＲｚを測定した。以上の結果を以下の表１に示す。 [Evaluation 2]
The nickel particles obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were measured for the shrinkage starting temperature of the nickel particles, the resistivity and the surface roughness Rz of the sintered film containing the nickel particles by the following methods. The results are shown in Table 1 below.
〔収縮開始温度の測定〕
ＴＭＡの測定装置としてセイコーインスツル株式会社製のＴМＡ／ＳＳ６０００を用いた。０．２～０．３ｇのニッケル粒子をφ５．０ｍｍのステンレス製の金型容器に入れ、ニッケル粒子に９２ＭＰａの圧力が加わるように加圧成形してペレットを作製した。得られたペレットのペレット長を測定し測定対象試料として用いた。これを測定装置にセットし、荷重４９ｍＮ、１体積％水素／９９体積％窒素雰囲気下において試料を５℃／ｍｉｎで昇温した。室温（２５℃）から測定を開始し、温度と収縮率（％）との関係を示すグラフを得た。得られたグラフから、収縮開始温度を求めた。 [Measurement of shrinkage start temperature]
As the TMA measuring device, TMA/SS6000 manufactured by Seiko Instruments Inc. was used. 0.2-0.3 g of nickel particles were placed in a stainless steel mold container with a diameter of 5.0 mm, and a pressure of 92 MPa was applied to the nickel particles to produce a pellet. The pellet length of the obtained pellet was measured and used as the measurement target sample. This was set in the measuring device, and the sample was heated at 5°C/min under a load of 49 mN and an atmosphere of 1% by volume hydrogen/99% by volume nitrogen. Measurement was started from room temperature (25°C), and a graph showing the relationship between temperature and shrinkage rate (%) was obtained. The shrinkage start temperature was determined from the obtained graph.
ＴＭＡの測定装置としてセイコーインスツル株式会社製のＴМＡ／ＳＳ６０００を用いた。０．２～０．３ｇのニッケル粒子をφ５．０ｍｍのステンレス製の金型容器に入れ、ニッケル粒子に９２ＭＰａの圧力が加わるように加圧成形してペレットを作製した。得られたペレットのペレット長を測定し測定対象試料として用いた。これを測定装置にセットし、荷重４９ｍＮ、１体積％水素／９９体積％窒素雰囲気下において試料を５℃／ｍｉｎで昇温した。室温（２５℃）から測定を開始し、温度と収縮率（％）との関係を示すグラフを得た。得られたグラフから、収縮開始温度を求めた。 [Measurement of shrinkage start temperature]
As the TMA measuring device, TMA/SS6000 manufactured by Seiko Instruments Inc. was used. 0.2-0.3 g of nickel particles were placed in a stainless steel mold container with a diameter of 5.0 mm, and a pressure of 92 MPa was applied to the nickel particles to produce a pellet. The pellet length of the obtained pellet was measured and used as the measurement target sample. This was set in the measuring device, and the sample was heated at 5°C/min under a load of 49 mN and an atmosphere of 1% by volume hydrogen/99% by volume nitrogen. Measurement was started from room temperature (25°C), and a graph showing the relationship between temperature and shrinkage rate (%) was obtained. The shrinkage start temperature was determined from the obtained graph.
〔比抵抗の測定〕
４ｇのターピネオールに０．１ｇのエチルセルロースを溶解させ、次いで５ｇのニッケル粒子を添加して混合物を得た。この混合物を、自転・公転ミキサー（株式会社シンキー製の「あわとり練太郎（登録商標）」）を用いて混合した。次いで、この混合物を３本ロールに４回通して解砕した。３本ロールのギャップは８μｍに設定した。このようして塗布液を得た。
この塗布液を、アルミナ基板に塗布して塗膜を形成した。塗膜の厚みは３０μｍであった。この塗膜を、１体積％水素／９９体積％窒素雰囲気下で８００℃、６０分間で焼結させて焼結膜を得た。この焼結膜について、三菱アナリテック社製の四探針法比抵抗測定装置であるロレスタＭＣＰ－Ｔ６００を用い、比抵抗（Ω・ｃｍ）を測定した。 [Measurement of resistivity]
0.1 g of ethyl cellulose was dissolved in 4 g of terpineol, and then 5 g of nickel particles was added to obtain a mixture. This mixture was mixed using a centrifugal mixer (Thinky Corporation's "Awatori Rentaro (registered trademark)"). Next, this mixture was passed through a three-roll mill four times to disintegrate the mixture. The gap between the three-roll mills was set to 8 μm. In this way, a coating solution was obtained.
This coating solution was applied to an alumina substrate to form a coating film. The coating film had a thickness of 30 μm. This coating film was sintered at 800° C. for 60 minutes in an atmosphere of 1% by volume hydrogen/99% by volume nitrogen to obtain a sintered film. The resistivity (Ω cm) of this sintered film was measured using a Loresta MCP-T600, a four-probe resistivity measuring device manufactured by Mitsubishi Analytech Co., Ltd.
４ｇのターピネオールに０．１ｇのエチルセルロースを溶解させ、次いで５ｇのニッケル粒子を添加して混合物を得た。この混合物を、自転・公転ミキサー（株式会社シンキー製の「あわとり練太郎（登録商標）」）を用いて混合した。次いで、この混合物を３本ロールに４回通して解砕した。３本ロールのギャップは８μｍに設定した。このようして塗布液を得た。
この塗布液を、アルミナ基板に塗布して塗膜を形成した。塗膜の厚みは３０μｍであった。この塗膜を、１体積％水素／９９体積％窒素雰囲気下で８００℃、６０分間で焼結させて焼結膜を得た。この焼結膜について、三菱アナリテック社製の四探針法比抵抗測定装置であるロレスタＭＣＰ－Ｔ６００を用い、比抵抗（Ω・ｃｍ）を測定した。 [Measurement of resistivity]
0.1 g of ethyl cellulose was dissolved in 4 g of terpineol, and then 5 g of nickel particles was added to obtain a mixture. This mixture was mixed using a centrifugal mixer (Thinky Corporation's "Awatori Rentaro (registered trademark)"). Next, this mixture was passed through a three-roll mill four times to disintegrate the mixture. The gap between the three-roll mills was set to 8 μm. In this way, a coating solution was obtained.
This coating solution was applied to an alumina substrate to form a coating film. The coating film had a thickness of 30 μm. This coating film was sintered at 800° C. for 60 minutes in an atmosphere of 1% by volume hydrogen/99% by volume nitrogen to obtain a sintered film. The resistivity (Ω cm) of this sintered film was measured using a Loresta MCP-T600, a four-probe resistivity measuring device manufactured by Mitsubishi Analytech Co., Ltd.
〔表面粗さＲｚの測定〕
前記の焼結膜の表面粗さＲｚを、ＳＵＲＦＣＯＭ １３０Ａを用いて測定した。測定条件は、評価長さ６．０ｍｍ、測定速度０．６ｍｍ／ｓとした。 [Measurement of surface roughness Rz]
The surface roughness Rz of the sintered film was measured using a SURFCOM 130A. The measurement conditions were an evaluation length of 6.0 mm and a measurement speed of 0.6 mm/s.
前記の焼結膜の表面粗さＲｚを、ＳＵＲＦＣＯＭ １３０Ａを用いて測定した。測定条件は、評価長さ６．０ｍｍ、測定速度０．６ｍｍ／ｓとした。 [Measurement of surface roughness Rz]
The surface roughness Rz of the sintered film was measured using a SURFCOM 130A. The measurement conditions were an evaluation length of 6.0 mm and a measurement speed of 0.6 mm/s.
表１に示す結果から明らかなとおり、ＸＰＳの測定によって、実施例１ないし９で得られたニッケル粒子はその表面域に金属状態のビスマス元素、銅元素、鉄元素又はモリブデン元素を含むことが確認された。更に、実施例で得られたニッケル粒子のａ軸長は、ビスマス元素、銅元素、鉄元素及びモリブデン元素の化合物を用いなかった比較例１で得られたニッケル粒子のａ軸長よりも伸びていた。これらの結果から、実施例１ないし６で得られたニッケル粒子はその表面域にニッケルとビスマスとの合金を含むことが分かる。また、実施例７で得られたニッケル粒子はその表面域にニッケルと銅との合金を含むことが分かる。また、実施例８で得られたニッケル粒子はその表面域にニッケルと鉄との合金を含むことが分かる。また、実施例９で得られたニッケル粒子はその表面域にニッケルとモリブデンとの合金を含むことが分かる。
また、表１に示す結果から明らかなとおり、実施例１ないし９で得られたニッケル粒子は、比較例１ないし３で得られたニッケル粒子と比べて高い収縮開始温度を示した。これによって、実施例１ないし９で得られたニッケル粒子は高い耐焼結性を示すことが分かる。
特に実施例１ないし５と実施例６との対比から明らかなとおり、ニッケル粒子に含まれるビスマスの量をコントロールすることで、該ニッケル粒子から得られる焼結膜の比抵抗をコントロールできることが分かる。
また、ニッケルとビスマスとの合金が形成された表面域を有するニッケル粒子を製造した実施例１ないし６は、ニッケル粒子全体においてニッケルとビスマスとの合金が形成された比較例２と比べて、焼結膜の表面が平滑なものとなった。これらによって、ニッケルとビスマスとの合金を含む表面域を有するニッケル粒子によれば、焼結膜の表面粗さが低くなることが分かる。 As is clear from the results shown in Table 1, it was confirmed by the XPS measurement that the nickel particles obtained in Examples 1 to 9 contain metallic bismuth, copper, iron, or molybdenum elements in their surface regions. Furthermore, the a-axis length of the nickel particles obtained in the examples was longer than the a-axis length of the nickel particles obtained in Comparative Example 1, which did not use compounds of bismuth, copper, iron, and molybdenum. From these results, it is understood that the nickel particles obtained in Examples 1 to 6 contain an alloy of nickel and bismuth in their surface regions. It is also understood that the nickel particles obtained in Example 7 contain an alloy of nickel and copper in their surface regions. It is also understood that the nickel particles obtained in Example 8 contain an alloy of nickel and iron in their surface regions. It is also understood that the nickel particles obtained in Example 9 contain an alloy of nickel and molybdenum in their surface regions.
Furthermore, as is clear from the results shown in Table 1, the nickel particles obtained in Examples 1 to 9 exhibited a higher shrinkage initiation temperature than the nickel particles obtained in Comparative Examples 1 to 3. This shows that the nickel particles obtained in Examples 1 to 9 exhibit high sintering resistance.
In particular, as is clear from the comparison between Examples 1 to 5 and Example 6, it is found that the resistivity of the sintered film obtained from the nickel particles can be controlled by controlling the amount of bismuth contained in the nickel particles.
Furthermore, in Examples 1 to 6 in which nickel particles having a surface region in which an alloy of nickel and bismuth was formed were produced, the surface of the sintered film was smoother than in Comparative Example 2 in which an alloy of nickel and bismuth was formed over the entire nickel particle. This shows that the surface roughness of the sintered film is reduced by using nickel particles having a surface region containing an alloy of nickel and bismuth.
また、表１に示す結果から明らかなとおり、実施例１ないし９で得られたニッケル粒子は、比較例１ないし３で得られたニッケル粒子と比べて高い収縮開始温度を示した。これによって、実施例１ないし９で得られたニッケル粒子は高い耐焼結性を示すことが分かる。
特に実施例１ないし５と実施例６との対比から明らかなとおり、ニッケル粒子に含まれるビスマスの量をコントロールすることで、該ニッケル粒子から得られる焼結膜の比抵抗をコントロールできることが分かる。
また、ニッケルとビスマスとの合金が形成された表面域を有するニッケル粒子を製造した実施例１ないし６は、ニッケル粒子全体においてニッケルとビスマスとの合金が形成された比較例２と比べて、焼結膜の表面が平滑なものとなった。これらによって、ニッケルとビスマスとの合金を含む表面域を有するニッケル粒子によれば、焼結膜の表面粗さが低くなることが分かる。 As is clear from the results shown in Table 1, it was confirmed by the XPS measurement that the nickel particles obtained in Examples 1 to 9 contain metallic bismuth, copper, iron, or molybdenum elements in their surface regions. Furthermore, the a-axis length of the nickel particles obtained in the examples was longer than the a-axis length of the nickel particles obtained in Comparative Example 1, which did not use compounds of bismuth, copper, iron, and molybdenum. From these results, it is understood that the nickel particles obtained in Examples 1 to 6 contain an alloy of nickel and bismuth in their surface regions. It is also understood that the nickel particles obtained in Example 7 contain an alloy of nickel and copper in their surface regions. It is also understood that the nickel particles obtained in Example 8 contain an alloy of nickel and iron in their surface regions. It is also understood that the nickel particles obtained in Example 9 contain an alloy of nickel and molybdenum in their surface regions.
Furthermore, as is clear from the results shown in Table 1, the nickel particles obtained in Examples 1 to 9 exhibited a higher shrinkage initiation temperature than the nickel particles obtained in Comparative Examples 1 to 3. This shows that the nickel particles obtained in Examples 1 to 9 exhibit high sintering resistance.
In particular, as is clear from the comparison between Examples 1 to 5 and Example 6, it is found that the resistivity of the sintered film obtained from the nickel particles can be controlled by controlling the amount of bismuth contained in the nickel particles.
Furthermore, in Examples 1 to 6 in which nickel particles having a surface region in which an alloy of nickel and bismuth was formed were produced, the surface of the sintered film was smoother than in Comparative Example 2 in which an alloy of nickel and bismuth was formed over the entire nickel particle. This shows that the surface roughness of the sintered film is reduced by using nickel particles having a surface region containing an alloy of nickel and bismuth.
本発明によれば、電気抵抗を過度に高めることなく耐焼結性が高いニッケル粒子が提供される。
The present invention provides nickel particles that are highly sinter-resistant without excessively increasing electrical resistance.
Claims (6)
- ニッケルと金属元素Ｍとの合金を含む表面域を有するニッケル粒子であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種であり、
前記ニッケル粒子全体に対する前記金属元素Ｍの含有量が０．０９質量％以上１５．８質量％以下であり、
Ｘ線光電子分光分析によって前記ニッケル粒子の深さ方向において最表面からＳｉＯ２換算でのスパッタ深さ５ｎｍまでの領域を測定したときに、該領域において、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合の最大値をＸ（ａｔ％）とし、
ＩＣＰ発光分光分析法によって前記ニッケル粒子を測定したとき、ニッケル元素と金属元素Ｍの合計原子数に対する金属元素Ｍの原子数の割合をＹ（ａｔ％）としたとき、
Ｘ／Ｙの値が０．５以上３５以下である、ニッケル粒子。 Nickel particles having a surface region comprising an alloy of nickel and a metallic element M,
The metal element M is at least one selected from bismuth, copper, iron, and molybdenum,
The content of the metal element M relative to the entire nickel particles is 0.09% by mass or more and 15.8% by mass or less,
When a region from the outermost surface to a sputtering depth of 5 nm in terms of SiO2 in the depth direction of the nickel particle is measured by X-ray photoelectron spectroscopy, the maximum value of the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M in the region is defined as X (at%);
When the nickel particles are measured by ICP atomic emission spectrometry, the ratio of the number of atoms of the metal element M to the total number of atoms of the nickel element and the metal element M is Y (at %),
Nickel particles having a value of X/Y of 0.5 or more and 35 or less. - 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０としたとき、Ｄ５０が２０ｎｍ以上２００ｎｍ以下であり、
前記粒度分布における粒径の標準偏差をσ（ｎｍ）としたとき、変動係数（σ／Ｄ５０）（％）の値が１４％以下である、請求項１に記載のニッケル粒子。
変動係数（％）＝（σ／Ｄ５０）×１００ In a particle size distribution based on a circle equivalent diameter calculated from a measurement using a scanning electron microscope, when a number cumulative particle diameter at a cumulative number of 50% by number is defined as D50 , D50 is 20 nm or more and 200 nm or less;
The nickel particles according to claim 1, wherein the standard deviation of particle size in the particle size distribution is σ (nm), and the coefficient of variation (σ/D 50 ) (%) is 14% or less.
Coefficient of variation (%) = (σ/D 50 ) × 100 - 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０としたとき、Ｄ５０の１．５倍以上の粒径を有する粒子の存在割合が０．５個数％以下である、請求項１に記載のニッケル粒子。 2. The nickel particles according to claim 1, wherein, in a particle size distribution based on a circle equivalent diameter calculated from measurement using a scanning electron microscope, when a number cumulative particle size at 50 % by number of cumulative particles is defined as D50, the proportion of particles having a particle size 1.5 times or more of D50 is 0.5% by number or less.
- 走査型電子顕微鏡による測定から算出された円相当直径に基づく粒度分布において、累積個数５０個数％における個数累積粒径をＤ５０とし、ＷＰＰＦ法によって測定された結晶子サイズをＣｓ（ｎｍ）としたとき、Ｃｓ／Ｄ５０の値が０．３以上０．６以下である、請求項１に記載のニッケル粒子。 In a particle size distribution based on a circle equivalent diameter calculated from measurement by a scanning electron microscope, the number cumulative particle size at 50% of the cumulative number is defined as D50 , and the crystallite size measured by the WPPF method is defined as Cs (nm), and the value of Cs/ D50 is 0.3 or more and 0.6 or less. The nickel particles according to claim 1.
- 水酸化ニッケル粒子、ポリオール、ポリビニルピロリドン及びポリエチレンイミンを含む混合液を加熱してニッケル粒子を製造する方法であって、
１質量部のポリエチレンイミンに対して、ポリビニルピロリドンを３０質量部以上２００質量部以下用い、
前記加熱によって前記水酸化ニッケル粒子をニッケル母粒子に還元し、
一部の前記水酸化ニッケル粒子が残存している状態で、前記混合液と金属元素Ｍの化合物とを混合し、該化合物を金属Ｍに還元して、前記ニッケル母粒子に、ニッケルと金属元素Ｍとの合金を含む表面域を形成する、ニッケル粒子の製造方法であって、
前記金属元素Ｍは、ビスマス、銅、鉄及びモリブデンから選ばれる少なくとも１種である、ニッケル粒子の製造方法。 A method for producing nickel particles by heating a mixed liquid containing nickel hydroxide particles, a polyol, polyvinylpyrrolidone, and polyethyleneimine, comprising the steps of:
Polyvinylpyrrolidone is used in an amount of 30 parts by mass or more and 200 parts by mass or less per part by mass of polyethyleneimine,
The heating reduces the nickel hydroxide particles to nickel base particles,
A method for producing nickel particles, comprising the steps of: mixing the mixed solution with a compound of a metal element M while some of the nickel hydroxide particles remain; reducing the compound to metal M; and forming a surface region containing an alloy of nickel and the metal element M on the nickel mother particles,
The method for producing nickel particles, wherein the metal element M is at least one selected from bismuth, copper, iron and molybdenum. - 請求項１ないし４のいずれか一項に記載のニッケル粒子を内部電極に用いた、積層セラミックコンデンサ。 A multilayer ceramic capacitor using nickel particles according to any one of claims 1 to 4 in the internal electrodes.
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