JP2004099383A - Method of manufacturing rare earth oxide phosphor - Google Patents
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- 229910001404 rare earth metal oxide Inorganic materials 0.000 title claims abstract description 138
- 238000004519 manufacturing process Methods 0.000 title claims description 26
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims description 11
- -1 transition metal salt Chemical class 0.000 claims abstract description 45
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 42
- 239000002253 acid Substances 0.000 claims abstract description 28
- 239000011541 reaction mixture Substances 0.000 claims abstract description 26
- 239000002071 nanotube Substances 0.000 claims abstract description 23
- 150000002910 rare earth metals Chemical class 0.000 claims abstract description 20
- 238000010304 firing Methods 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- 150000003839 salts Chemical class 0.000 claims abstract description 10
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000004202 carbamide Substances 0.000 claims abstract description 9
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 9
- 239000002131 composite material Substances 0.000 claims description 68
- 238000000034 method Methods 0.000 claims description 31
- 229910052693 Europium Inorganic materials 0.000 claims description 23
- 125000001741 organic sulfur group Chemical group 0.000 claims description 23
- 150000001450 anions Chemical class 0.000 claims description 21
- 238000001354 calcination Methods 0.000 claims description 21
- 230000001590 oxidative effect Effects 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid group Chemical group S(O)(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 15
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 claims description 14
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 13
- 239000010949 copper Substances 0.000 claims description 12
- 239000011572 manganese Substances 0.000 claims description 11
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 10
- 229910052802 copper Inorganic materials 0.000 claims description 10
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 9
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 9
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 claims description 9
- 239000011229 interlayer Substances 0.000 claims description 9
- 229910052747 lanthanoid Inorganic materials 0.000 claims description 9
- 150000002602 lanthanoids Chemical class 0.000 claims description 9
- 229910052748 manganese Inorganic materials 0.000 claims description 9
- 125000005586 carbonic acid group Chemical group 0.000 claims description 6
- 239000003054 catalyst Substances 0.000 claims description 6
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 2
- 239000011593 sulfur Substances 0.000 claims description 2
- FPVGTPBMTFTMRT-NSKUCRDLSA-L fast yellow Chemical group [Na+].[Na+].C1=C(S([O-])(=O)=O)C(N)=CC=C1\N=N\C1=CC=C(S([O-])(=O)=O)C=C1 FPVGTPBMTFTMRT-NSKUCRDLSA-L 0.000 claims 2
- 150000002894 organic compounds Chemical class 0.000 claims 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims 1
- 239000000843 powder Substances 0.000 abstract description 5
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- 125000000129 anionic group Chemical group 0.000 abstract description 3
- 239000007858 starting material Substances 0.000 abstract 1
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 16
- 229910052727 yttrium Inorganic materials 0.000 description 14
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
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- 238000000295 emission spectrum Methods 0.000 description 6
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- NGDQQLAVJWUYSF-UHFFFAOYSA-N 4-methyl-2-phenyl-1,3-thiazole-5-sulfonyl chloride Chemical compound S1C(S(Cl)(=O)=O)=C(C)N=C1C1=CC=CC=C1 NGDQQLAVJWUYSF-UHFFFAOYSA-N 0.000 description 4
- 229910052765 Lutetium Inorganic materials 0.000 description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 4
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 4
- 229910052769 Ytterbium Inorganic materials 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 description 4
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- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 150000001805 chlorine compounds Chemical class 0.000 description 3
- MOTZDAYCYVMXPC-UHFFFAOYSA-N dodecyl hydrogen sulfate Chemical compound CCCCCCCCCCCCOS(O)(=O)=O MOTZDAYCYVMXPC-UHFFFAOYSA-N 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
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- 239000000377 silicon dioxide Substances 0.000 description 3
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- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 229910052771 Terbium Inorganic materials 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- QFLPBJNIAWVWJE-UHFFFAOYSA-N [O--].[O--].[O--].[Y+3].[Eu+3] Chemical compound [O--].[O--].[O--].[Y+3].[Eu+3] QFLPBJNIAWVWJE-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
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- NNMXSTWQJRPBJZ-UHFFFAOYSA-K europium(iii) chloride Chemical compound Cl[Eu](Cl)Cl NNMXSTWQJRPBJZ-UHFFFAOYSA-K 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
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- KHIWWQKSHDUIBK-UHFFFAOYSA-N periodic acid Chemical class OI(=O)(=O)=O KHIWWQKSHDUIBK-UHFFFAOYSA-N 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
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- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000264877 Hippospongia communis Species 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-L Malonate Chemical compound [O-]C(=O)CC([O-])=O OFOBLEOULBTSOW-UHFFFAOYSA-L 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 1
- 150000008051 alkyl sulfates Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000005349 anion exchange Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
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- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 description 1
- 229940043264 dodecyl sulfate Drugs 0.000 description 1
- 229910001940 europium oxide Inorganic materials 0.000 description 1
- AEBZCFFCDTZXHP-UHFFFAOYSA-N europium(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Eu+3].[Eu+3] AEBZCFFCDTZXHP-UHFFFAOYSA-N 0.000 description 1
- GAGGCOKRLXYWIV-UHFFFAOYSA-N europium(3+);trinitrate Chemical compound [Eu+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O GAGGCOKRLXYWIV-UHFFFAOYSA-N 0.000 description 1
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- APRNQTOXCXOSHO-UHFFFAOYSA-N lutetium(3+);trinitrate Chemical compound [Lu+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O APRNQTOXCXOSHO-UHFFFAOYSA-N 0.000 description 1
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- 229910001935 vanadium oxide Inorganic materials 0.000 description 1
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Images
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、希土類イオンの光学的および化学特性を利用した演算・メモリ素子、発光素子、センサ素子等のフォトニクス・エレクトロニクス・情報技術用基礎素材または機能素子、各種化学反応に対する触媒などとして使用される希土類酸化物の製造法に関する。特にナノチューブ構造、六方構造、もしくは層状構造を有する希土類酸化物複合体を前駆体として誘導された高性能の希土類酸化物の製造方法及び希土類酸化物に関する。ここに、本発明において言う希土類酸化物は、高純度の希土類酸化物は勿論、他の金属がドープしてなるものまでも含むものである。
【０００２】
【従来の技術】
希土類元素は、その４ｆ電子に起因する特異な磁性や分光学的および化学的性質を有し、従来より、高性能磁石、発光材料、触媒などとして広く用いられてきた。中でも、希土類酸化物の（Ｙ、Ｅｕ）２Ｏ３と酸化硫化物の（Ｙ，Ｅｕ）２Ｏ２Ｓは代表的な赤色蛍光体であり、各々蛍光ランプ及びカラーテレビブラウン管用蛍光体として用いられている。前者は、例えば、酸化イットリウムと酸化ユーロピウムの硝酸溶液にシュウ酸水溶液を加えてできるシュウ酸塩共沈物を１２００℃で焼成することにより、後者は、例えば、Ｙ２Ｏ３，Ｅｕ２Ｏ３，Ｓ，Ｎａ２ＣＯ３の混合物を１１００−１３００℃で焼成し、遊離のＮａ２Ｓを水洗除去することにより製造される（荒井康夫、セラミックスの材料化学、大日本図書、昭和６年、Ｐ３００）。
【０００３】
これらの蛍光体材料の多くは、従来粒径数ミクロン程度の微粒子として使用されてきたが、近年、電子部品の微小化・高性能化が進む中で微粉体を均一に分散させる必要性が高まり、粒径が小さく、かつ分散性に優れた希土類酸化物が求められている（西須佳宏、資源環境技術総合研究所ＮＩＲＥニュース、１９９５年１月）。さらに材料の機能やその性能は、粒子形状や大きさのみならず、母体の組成、構造に敏感に依存することが指摘されている〔足立吟也、「希土類の化学」１４章、化学同人編（１９９９）〕。
そのため、尿素の分解反応を利用して均質で緻密な単分散微粒子を調製する均一沈殿法等が開発されているが、従来技術は球状もしくは不定形の超微粒子を提供するに留まっており、多成分系材料中の元素分布等の微細構造をナノメートルスケールで制御する技術を確立するには至っていない。
【０００４】
一方、ナノスケールの新規構造をもつ無機物質合成法として、１９９３年にＭｏｂｉｌ社により界面活性剤を鋳型として２〜８ｎｍのハニカム状メソ細孔を有するメソボーラスシリカを創製する手法が開発され〔Ｃ．Ｔ．Ｋｒｅｓｇｅほか４名、Ｎａｔｕｒｅ、３５９、ｐ．７１０〜７１２（１９９２）〕、その後、同様の手法により、シリカ以外の種々の金属酸化物や硫化物、単体金属を骨格成分とするメソ多孔体が相次いで合成された〔木島剛ほか１名、Ｊ．Ｓｏｃ．Ｉｎｏｒｇ．Ｍａｔｅｒ、８、ｐ．３〜１６（２００１）〕。
【０００５】
さらに、最近、この鋳型合成法が無機ナノチューブの合成にも応用され、酸化バナジウム〔Ｍ．Ｅ．Ｓｐａｈｒほか５名、Ａｎｇｅｗ．Ｃｈｅｍ．Ｉｎｔ．Ｅｄ、３７、ｐ．１２６３〜６５（１９９８）〕、シリカ〔Ｍ．Ａｄａｃｈｉほか２名、Ｌａｎｇｍｕｉｒ、１５、（１９９９）〕、チタニア〔Ｈ．Ｉｍａｉほか４名、Ｊ．Ｍａｔｅｒ．Ｃｈｅｍ、９、２９７１、（１９９９）〕などの酸化物系ナノチューブが報告されている。
【０００６】
その間、本発明者等のグループにおいても、ドデシル硫酸イオンを鋳型として、尿素を用いる均一沈殿法により、アルミニウム系〔Ｍ．Ｙａｄａほか４名、Ｉｎｏｒｇ．Ｃｈｅｍ、３６、５５６５〜６９（１９９７）〕、イットリウム系〔Ｍ．Ｙａｄａほか３名、Ｉｎｏｒｇ．Ｃｈｅｍ、３７、６４７０〜７５（１９９８）〕、ランタノイド系〔Ｍ．Ｙａｄａほか４名、Ａｎｇｅｗ．Ｃｈｅｍ．Ｉｎｔ．Ｅｄ、３８、３５０６〜０９（１９９９）〕などの各種六方構造型酸化物メソ複合体及び層状構造複合体を合成し〔Ｍ．Ｙａｄａほか１名、Ｒｅｃｅｎｔ Ｒｅｓ．Ｄｅｖｅｌ．Ｉｎｏｒｇ．Ｃｈｅｍ、２、２５〜３９（２０００）〕、さらに希土類酸化物ナノチューブの合成にも成功している〔Ｍ．Ｙａｄａほか４名、Ａｄｖ．Ｍａｔｅｒ．、２５〜３９（２００２）〕。
また、希土類酸化物系については、鋳型イオンを酢酸イオンで交換することにより多孔体化できることを初めて見出している〔前記Ｉｎｏｒｇ．Ｃｈｅｍ、３７、６４７０〜７５（１９９８）〕、Ａｎｇｅｗ．Ｃｈｅｍ．Ｉｎｔ．Ｅｄ、３８、３５０６〜０９（１９９９）〕。
【０００７】
界面活性剤を鋳型として得られる上記無機ナノ構造体は、いずれもナノチューブ、ハニカム状もしくは層状の長周期構造を有するとともに、その骨格をなす構成原子が結晶のような規則的配列をとらず、非晶質構造にやや近い特有の秩序度をとっていることに特徴がある〔木島剛ほか１名、Ｊ．Ｓｏｃ．Ｉｎｏｒｇ．Ｍａｔｅｒ、８、ｐ．３〜１６（２００１）〕。
【０００８】
【発明が解決しようとする課題】
本発明は、以上、従来技術において紹介、列挙した希土類酸化物ならびに無機ナノ構造体の合成法に関する多岐にわたる研究報告、先行技術を念頭に置きつつ、これらとは異なる新規な組成、構造を有するナノ構造体を中間体として新規な性能を有する希土類酸化物の製造方法を提供しようというものである。特に、その骨格に光活性な希土類イオンを効果的に組み込むことにより優れた発光特性を有する希土類酸化物発光体を提供しようというものである。また、これによって、電子、情報、環境分野の技術革新に寄与する新規素材を提供しようとするものである。
【０００９】
上記従来技術に示した先行技術に開示された中、本発明に関連のある知見として、ナノチューブ、ハニカム状もしくは層状の長周期構造を有する希土類酸化物に関する報告があげられるが、複数の希土類成分を基本骨格として導入することないしは導入しうることについては、全く開示、言及されておらず、ましてやこれらを中間体として、新規な構造や性能を有する希土類酸化物を製造する方法については提案も示唆もされてはいない。また、この点は、その他の先行文献においても同様である。
【００１０】
【課題を解決するための手段】
そこで、本発明者は、前記目的を達成すべく、用いる希土類元素の種類と反応条件についてさらに鋭意研究を進めた結果、本発明に到達しえたものである。
特に、有機硫黄酸基を含みナノチューブ状、ハニカム状もしくは層状構造を有する希土類酸化物複合体を前駆体として、常法により焼成することにより、従来方法で作製したものに比べて格段に高性能の希土類酸化物を製造できることを見出した。
【００１１】
すなわち、本発明者等は、鋭意研究をした結果、前示課題を以下（１）ないし（１４）に記載する技術的構成を講ずることによって解決することに成功したものである。
【００１２】
その第１の解決手段は、（１）一種又は二種以上の希土類金属塩、有機硫黄酸塩、尿素、水からなる反応混合物、又はこれに一種又は二種以上の遷移金属塩を加えた反応混合物を調製し、次いでこの反応混合物を反応させて、前記希土類成分を含む複合酸化物を主成分、炭酸基ならびに有機硫黄酸基を副成分とする骨格から成り、外径約５〜７ｎｍ、内径約２〜４ｎｍ、長さ１０ｎｍ以上のナノチューブ構造、格子定数５〜７ｎｍの六方構造、もしくは層間距離３〜６ｎｍの層状構造を有する希土類酸化物複合体を生成し、次いで該希土類酸化物複合体をその中の少なくとも有機硫黄酸基が熱分解する温度で焼成処理を行うか、あるいは、該希土類酸化物複合体を短鎖長有機酸塩及び無機酸塩の何れか一種を含むアルコール溶液と反応させ、該希土類酸化物複合体中の有機硫黄酸基を該溶液中の陰イオンと置換せしめた後、該希土類酸化物複合体中の少なくとも置換陰イオン基が熱分解する温度で焼成処理を行うことを特徴とする希土類酸化物の製造方法である。
【００１３】
また、第２の発明から第６の解決手段は、第１の解決手段から派生したものであり、第２の解決手段は、（２）前記出発反応混合物がユーロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）を含むランタイノド元素の１種、またはマンガン、銅を少なくとも一部含有してなるものであり、これによって骨格内希土類サイトに該金属が一部ドープされた、希土類成分を含む複合酸化物を主成分、炭酸基ならびに有機硫黄酸基を副成分とする骨格から成り、外径約５〜７ｎｍ、内径約２〜４ｎｍ、長さ１０ｎｍ以上のナノチューブ構造、格子定数５〜７ｎｍの六方構造、もしくは層間距離３〜６ｎｍの層状構造を有する希土類酸化物複合体を生成し、次いで該希土類酸化物複合体をその中の少なくとも有機硫黄酸基が熱分解する温度で焼成処理を行うか、あるいは、該希土類酸化物複合体を短鎖長有機酸塩及び無機酸塩の何れか一種を含むアルコール溶液と反応させ、該希土類酸化物複合体中の有機硫黄酸基を該溶液中の陰イオンと置換せしめた後、該希土類酸化物複合体中の少なくとも置換陰イオン基が熱分解する温度で焼成処理を行い、希土類酸化物の骨格内希土類サイトに該金属が一部ドープされている生成物を得ることを特徴とするユーロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）を含むランタイノド元素の１種、またはマンガン、銅が少なくともドープされている前記（１）項に記載の希土類酸化物の製造方法。
【００１４】
第３の解決手段は、（３）前記焼成処理が、酸化性雰囲気中４５０℃以上で行われることを特徴とする前記（１）項に記載の希土類酸化物の製造方法。
（４） 前記焼成処理が、酸化性雰囲気中４５０℃以上で行われることを特徴とする前記（２）項に記載の希土類酸化物の製造方法。
（５） 前記焼成処理が、酸化性雰囲気中６００℃以下で希土類酸化物複合体を構成する有機硫黄酸基または置換陰イオン基を分解させる前焼成と、次いで還元性雰囲気中６００℃以上で行う後焼成とによる、２段階工程によって行われることを特徴とする前記（１）項に記載の希土類酸化物の製造方法。
（６） 前記焼成処理が、酸化性雰囲気中６００℃以下で希土類酸化物複合体を構成する有機硫黄酸基または置換陰イオン基を分解させる前焼成と、次いで還元性雰囲気中６００℃以上で行う後焼成とによる、２段階工程によって行われることを特徴とする前記（２）項に記載の希土類酸化物の製造方法。
【００１５】
第７ないし第１２の解決手段は、第１から第６までの各製造方法によって得られてなる希土類酸化物自体に係るものである。
すなわち、（７）一種又は二種以上の希土類金属塩、有機硫黄酸塩、尿素、水からなる反応混合物、又はこれに一種又は二種以上の遷移金属塩を加えた反応混合物を調製し、次いでこの反応混合物を反応させて、前記希土類成分を含む複合酸化物を主成分、炭酸基ならびに有機硫黄酸基を副成分とする骨格から成り、外径約５〜７ｎｍ、内径約２〜４ｎｍ、長さ１０ｎｍ以上のナノチューブ構造、格子定数５〜７ｎｍの六方構造、もしくは層間距離３〜６ｎｍの層状構造を有する希土類酸化物複合体を生成し、次いで該希土類酸化物複合体をその中の少なくとも有機硫黄酸基が熱分解する温度で焼成処理を行うか、あるいは、該希土類酸化物複合体を短鎖長有機酸塩及び無機酸塩の何れか一種を含むアルコール溶液と反応させ、該希土類酸化物複合体中の有機硫黄酸基を該溶液中の陰イオンと置換せしめた後、該希土類酸化物複合体中の少なくとも置換陰イオン基が熱分解する温度で焼成処理を行う、以上のプロセスによって得られてなることを特徴とする希土類酸化物。
【００１６】
（８）前記出発反応混合物がユーロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）を含むランタイノド元素の１種、またはマンガン、銅を少なくとも一部含有してなるものであり、これによって骨格内希土類サイトに該金属が一部ドープされた、希土類成分を含む複合酸化物を主成分、炭酸基ならびに有機硫黄酸基を副成分とする骨格から成り、外径約５〜７ｎｍ、内径約２〜４ｎｍ、長さ１０ｎｍ以上のナノチューブ構造、格子定数５〜７ｎｍの六方構造、もしくは層間距離３〜６ｎｍの層状構造を有する希土類酸化物複合体を生成し、次いで該希土類酸化物複合体をその中の少なくとも有機硫黄酸基が熱分解する温度で焼成処理を行うか、あるいは、該希土類酸化物複合体を短鎖長有機酸塩及び無機酸塩の何れか一種を含むアルコール溶液と反応させ、該希土類酸化物複合体中の有機硫黄酸基を該溶液中の陰イオンと置換せしめた後、該希土類酸化物複合体中の少なくとも置換陰イオン基が熱分解する温度で焼成処理を行い、希土類酸化物の骨格内希土類サイトに該金属が一部ドープされている生成物を得る、以上のプロセスによって得られてなることを特徴とするユーロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）を含むランタイノド元素の１種、またはマンガン、銅が少なくともドープされている前記（７）項に記載の希土類酸化物。
【００１７】
（９）前記焼成処理が、酸化性雰囲気中４５０℃以上で行われることを特徴とする前記（７）項に記載の希土類酸化物。
（１０）前記焼成処理が、酸化性雰囲気中４５０℃以上で行われることを特徴とする前記（８）項に記載の希土類酸化物。
（１１）前記焼成処理が、酸化性雰囲気中６００℃以下で希土類酸化物複合体を構成する有機硫黄酸基または置換陰イオン基を分解させる前焼成と、次いで還元性雰囲気中６００℃以上で行う後焼成とによる、２段階工程によって行われることを特徴とする前記（７）項に記載の希土類酸化物。
（１２） 前記焼成処理が、酸化性雰囲気中６００℃以下で希土類酸化物複合体を構成する有機硫黄酸基または置換陰イオン基を分解させる前焼成と、次いで還元性雰囲気中６００℃以上で行う後焼成とによる、２段階工程によって行われることを特徴とする前記（８）項に記載の希土類酸化物。
【００１８】
第１３番目、第１４番目の解決手段は、前記希土類酸化物を蛍光体材料及び触媒材料として供するものである。
すなわち、１３番目の解決手段は、（１３）前記（７）ないし（１２）の何れか１項に記載の希土類酸化物を用いてなることを特徴とする蛍光体材料である。また、１４番目の解決手段は、（１４）前記（７）ないし（１２）の何れか１項に記載の希土類酸化物を用いてなることを特徴とする触媒材料である。
【００１９】
【発明の実施の形態】
本発明は、ナノチューブ構造、六方構造、もしくは層状構造を有する希土類酸化物複合体を前駆体として誘導された高性能の希土類酸化物の製造方法及び希土類酸化物を提供するところにあることは、前述したとおりである。前駆体となる希土類酸化物複合体は、一種以上の特定希土類等の金属酸化物を主成分とし、炭酸基と有機硫黄酸基を副成分とする骨格から成る特定寸法のナノチューブ構造体、六方構造体、もしくは層状構造体であり、その構成成分は、主要成分、副成分自体に関しても、組成的に多様な組み合わせを許容するものであることに加え、主成分サイト、副成分サイトは、イオン交換操作によって、他の希土類金属元素、遷移金属元素、あるいは他の有機酸陰イオン、無機酸陰イオンによって二次的に置換されることから、実に多様な組み合わせを含むものである。したがってまた、これらの希土類酸化物複合体を焼成処理することによって誘導される希土類酸化物の含有成分と構造も同様に多様な組み合わせを含むことはいうまでもない。さらに、以下に提示する実施例は、本発明に対して、あくまでもその一態様例を示すものにすぎず、本発明をこの実施例によって限定されるべきではない。
【００２０】
本発明に係わる希土類金属塩は、スカンジウム（Ｓｃ）、イットリウム（Ｙ）、及びユーロピウム（Ｅｕ）、テリビウム（Ｔｂ）、ガドリニウム（Ｇｄ）を含むランタノイド元素の硝酸塩、塩化物等、マンガン（Ｍｎ）、銅（Ｃｕ）を含む遷移金属の硝酸塩、塩化物等の希土類金属塩及び遷移金属塩をいずれか１種以上使用する。２種以上の希土類金属塩のうち、いずれか１種はイットリウム（Ｙ）、イッテリビウム（Ｙｂ）またはルテチウム（Ｌｕ）の硝酸塩、塩化物等を用いることが望ましい。
【００２１】
本発明に係わる有機硫黄酸塩としては、例えば、ドデシル硫酸ナトリウム、ドデシルベンゼンスルホン酸ナトリウム等が挙げられる。
【００２２】
本発明に係わる短鎖長有機酸塩としては、例えば、酢酸塩、マロン酸塩等が挙げられる。
【００２３】
本発明に係わる無機酸塩としては、例えば、過ヨウ素酸塩、三ヨウ化物塩等が挙げられる。
【００２４】
以下、本発明を図面及び実施例に基づいて説明する。但し、これらの実施例は、本発明を理解するための一助として具体例を以て示すものであり、本発明は、この実施例に限定されないし、限定されることはない。
【００２５】
図１（ａ）は、本発明の実施例１で得られた中間体であるナノチューブ構造のイットリウム、イッテリビウム及びルテチウム系酸化物複合体のＸ線回折図である。図１（ｂ）は、その透過形電子顕微鏡による観察写真であり、これによると、本発明の希土類酸化物化合物は中空のチューブ状構造を呈していることが観察される。図２（ａ）は、実施例１においてナノチューブ状複合体を前駆体として得られた３％ユーロピウムドープ酸化イットリウム３％Ｅｕ／ＮＴ（Ｙ）（１０００℃焼成）と、従来法の均一沈殿法で得られた３％Ｅｕドープ酸化イットリウム３％Ｅｕ／Ｂｕｌｋ（Ｙ）（１０００℃焼成）との発光スペクトルを対比して示した図である。図２（ｂ）は、前者試料の透過形電子顕微鏡による観察写真である。
【００２６】
また、図３（ａ）は実施例２で得られた中間体であるヘキサゴナル構造型イットリウム系酸化物複合体のＸ線回折図であり、各ユーロピウム（Ｅｕ）含有量ごとに示している。図３（ｂ）は、同じく５％Ｅｕドープ試料の透過形電子顕微鏡写真であり、これによるとヘキサゴナル構造特有のパターンが認められる。図３（ｃ）は、従来法の均一沈殿法で得られた３％Ｅｕドープ酸化イットリウムの透過形電子顕微鏡写真であり、バルク状形態が認められる。
【００２７】
図４（ａ）は、実施例２においてヘキサゴナル構造複合体を前駆体として得られた３％及び５％Ｅｕドープ酸化イットリウムの各Ｘ線回折図を示し、図４（ｂ）は同じく５％Ｅｕドープ試料の透過形電子顕微鏡写真である。そして、図４（ｃ）は、実施例２において得られた１％、３％及び５％Ｅｕドープした酸化イットリウムと、均一沈殿法で得られた３％Ｅｕドープ酸化イットリウムとの発光スペクトル（励起波長３９５ｎｍ）を対比して示した図である。
【００２８】
実施例１
硝酸イットリウム、塩化ユーロピウム、ドデシル硫酸ナトリウム、尿素、および水を０．９７：０．０３：２：３０：６０のモル比で混合し反応混合物を調製した。得られた反応混合物を加熱反応容器に入れ、４０℃で１時間攪拌した後、８０℃で１００時間反応させた。反応液中に生成した微細な固相が析出した。これを遠心分離後、水洗し、４０℃で乾燥して中間体である複合体を得た。同様な操作により、硝酸イットリウムの代わりに硝酸ルテチウムと硝酸イットリビウムを用いた試料も各々作製した。
次いで、この複合体を、空気中、１０００℃で３時間焼成し、最終生成物である酸化ユーロピウムイットリウムを得た。また、界面活性剤を添加しない同様の反応によって得られた沈殿物を同じ条件で焼成し、酸化物を得た。
まず、中間体としての複合体は、ナノチューブ構造の００１、００２、００３回折線に相当するｄ＝６．３ｎｍ、２．９ｎｍおよび１．９ｎｍの３本の長周期ピークで特徴づけられるＸ線回折図形を与えた〔図１（ａ）〕。
また、透過型電子顕微鏡による観察により、外径６ｎｍ、内径３ｎｍ、チューブ状生成物であることも確認された〔図１（ｂ）〕。さらに、赤外吸収（ＦＴ−ＩＲ）スペクトルより、ドデシル硫酸基の存在が確認され、ＥＤＸから求めたＥｕのドープ量と仕込み量との比率は約５８％であった。
得られた焼成体は、酸化イットリウムと同型の結晶構造を有していることがＸ線回折分析によって確認された〔その回折パターンは図４（ａ）に同様であった〕。 その粉末の形態は、バルク状形態をもつことが観察された〔図２（ｂ）〕。
図２（ａ）は、上述の方法で得られた希土類酸化物と、界面活性剤を添加しない従来法で得られた希土類酸化物の発光スペクトルを示す。同図より明らかなように、本発明によるある希土類酸化物は、従来法による希土類酸化物の約２倍の発光強度を示し、その性能が飛躍的に向上していることが理解される。
【００２９】
実施例２
硝酸イットリウム、塩化ユーロピウム、ドデシル硫酸ナトリウム、尿素、および水を０．９５：０．０５：２：３０：６０のモル比で混合し反応混合物を調製した。得られた反応混合物を加熱反応容器に入れ、４０℃で１時間攪拌した後、８０℃で２０時間反応させた。反応液中に生成した微細な固相が析出した。これを遠心分離後、水洗し、４０℃で乾燥して中間体である複合体を得た。
次いで、この複合体を、空気中、１０００℃で５時間焼成し、最終生成物である酸化ユーロピウム・イットリウムを得た。また、界面活性剤を添加しない同様の反応によって得られた沈殿物を同じ条件で焼成し、酸化物を得た。
まず、中間体としての複合体は、そのＸ線回折図形〔図３（ａ）〕と透過型電子顕微鏡像〔図３（ｂ）〕より、格子定数５．４ｎｍのヘキサゴナル構造を持つメソ構造体であるここが確認された。さらに、赤外吸収（ＦＴ−ＩＲ）スペクトルより、ドデシル硫酸基の存在が確認され、ＥＤＸから求めたＥＤＸから求めたＥｕのドープ量と仕込み量との比率は約４４％であった。なお、図３（ｃ）は、従来法による沈殿法で得られたＥｕドープ酸化イットリウムの透過型電子顕微鏡写真であり、これによればバルク状形態が観察される。
焼成体は、バルク状を呈し〔図４（ｂ）〕、酸化イットリウムと同型の結晶構造を有していることがＸ線回折図形より確認された〔図４（ａ）〕。図４（ｃ）は、上述の方法で得られた希土類酸化物と、界面活性剤を添加しない従来法で得られた希土類酸化物の発光スペクトルを示す。チューブ状複合体を中間体として作製した場合と同様に、ヘキサゴナル構造複合体を経て得られた希土類酸化物も、従来法による希土類酸化物の約２倍の発光強度を示し、その性能が飛躍的に向上していることが分かる。
【００３０】
本発明は、以上の実施例に加え、多岐にわたる実験例を積み重ね、得られたデータを整理した結果、有機硫黄酸基を含みナノチューブ構造、ヘキサゴナル構造もしくは層状構造を有する希土類酸化物複合体を前駆体として、常法により焼成することにより、従来方法で作製したものに比べて格段に高性能の希土類酸化物を製造できることが確認されたものである。本発明にかかる希土類酸化物の性能が優れる理由は現時点では明確でないが、上記のようなナノ構造を経由することにより、希土類酸化物結晶中のユーロピウムイオン等の分布の均一性が増し、その結果該元素の励起エネルギーが有効に発光に利用されることによるものと推測される。
【００３１】
本発明は、希土類元素を有する特異結晶構造の希土類酸化物の新規な製造方法を開発することに成功したものであり、その工業的意義は極めて大である。その詳細な物性や、諸特性及び各種技術分野における作用効果に関する具体的データ等の開示、及びこれに関漣して誘導される新たな技術的可能性、発展性等の研究開発は、今後の研究に待つところ大であり、委ねられているものであるが、その組成と特異結晶構造からして、諸分野において優れた作用効果を奏しうることが期待される。
【００３２】
すなわち、紫外線・可視光線照射時の発光強度と発光効率に優れてなる光変換素子機能、各種反応における触媒機能などの各種有用な機能を有し、これら有用機能の発現によって期待される各種用途に供することのできる希土類酸化物を得るのに成功したものである。
【００３３】
ここに、この希土類酸化物の製造法は、前記実施例で具体的、個別的に開示したところであるが、これを、反応混合物の調製から実施する場合の製造方法における反応条件について言及、要約すると、以下の通りである。
先ず、中間体である希土類酸化物複合体の製造方法は、▲１▼イットリウム（Ｙ）、イッテリビウム（Ｙｂ）またはルテチウム（Ｌｕ）の硝酸塩、塩化物等の金属塩をいずれか１種、ユーロピウム（Ｅｕ）、テリビウム（Ｔｂ）、ガトリニウム（Ｇｄ）を含むランタノイド元素の硝酸塩、塩化物等、マンガン（Ｍｎ）、銅（Ｃｕ）を含む遷移金属の硝酸塩、塩化物等の希土類金属塩及び遷移金属塩をいずれか１種以上、有機硫黄酸塩、尿素、水を混合し、一定時間反応させることによりナノチューブ構造、六方構造、もしくは層状構造を有する希土類酸化物複合体を製造する方法、及び▲２▼前項で得られた複合体をさらに短鎖長有機酸塩及び無機酸塩の何れか一種を含むアルコール溶液と反応させ、該複合体中の有機硫黄酸基を該溶液中の陰イオンと置換せしめた希土類酸化物複合体を製造する方法に大別される。
【００３４】
その反応条件は、例示的に要約すると以下の通りである。
すなわち、▲１▼イットリウムとユーロピウムを希土類成分とするチューブ状化複合体は、硝酸イットリウム０．９５モル、硝酸ユーロピウム０．５モルに対し、ドデシル硫酸ナトリウムを１〜３モル好ましくは２モル、尿素を２０〜５０モル好ましくは３０モル、水を４０から８０モル好ましくは６０モルを加えて混合し、４０℃で１時間攪拌した後、７０〜８５℃で５０時間以上、好ましくは８０℃で１００時間保持することにより製造する。▲２▼イットリウムとユーロピウムを希土類成分とする六方構造複合体は、▲１▼と同様に調製した反応混合物を７０〜８５℃で１０〜３０時間好ましくは８０℃で２０時間保持することにより製造する。▲３▼イットリウムとユーロピウムを希土類成分とする層状構造複合体は、▲１▼と同様に調製した反応混合物を７０〜８５℃で３〜５時間好ましくは８０℃で４時間保持することにより製造する。
【００３５】
上記の▲１▼ ▲３▼の反応により得られた固体生成物を液より分離し、水洗後、３０〜４０℃で１２〜２４時間乾燥すると、各々、希土類元素を骨格成分とするナノチューブ構造、六方構造及び層状構造を有する複合体から得られる。これらの化合物は、各々、希土類酸化物骨格中に炭素基と有機硫黄酸基（アルキル硫酸基）が取り込まれた外径約６ｎｍ、内径３ｎｍのチューブ状構造、格子定数６ｎｍの六方構造、層間距離４ｎｍの層状構造を有することが明らかとなった。
【００３６】
また、各複合体の有機硫黄酸基（アルキル硫酸基）含有チューブ化合物を酢酸、マロン酸等の有機酸、もしくは過ヨウ素酸、三ヨウ化合物イオン等の無機酸を含むアルコール溶液と反応させることにより化合物中の該有機硫黄酸基のサイトがアルコール溶液中に含まれている。
有機酸イオン、無機酸イオンによって置換された希土類酸化物ナノチューブを得ることができることは、如上の通りである。
この置換による製造方法における反応条件について、以下、例示的に言及、要約する。例えば、アルキル硫酸基含有チューブ状化合物０．５ｇを酢酸ナトリウムの０．０５ｍｏｌ／ｌエタノール溶液４０ｍｌに分散させ、４０℃で１時間反応させることにより母体中のアルキル硫酸イオンと外部溶液中の酢酸イオンとの陰イオン交換が起こり、チューブの内径はイオン交換処理前の約２．５ｎｍから約３ｎｍに増大し、目的物が製造し得られる。アルキル硫酸基含有六方構造化合物及びアルキル硫酸基含有層状構造化合物についても、同様の処理によりイオン置換体が得られる。
【００３７】
次いで、得られたナノチューブ構造、六方構造及び層状構造を有する複合体を各々酸化性雰囲気中４５０〜６００℃好ましくは５００℃で、１〜１０時間の前焼成を行う。さらに、少なくとも８００℃以上好ましくは１０００〜１２００℃で後焼成を行い、希土類酸化物を得る。
【００３８】
また、後焼成の段階で、硫黄含有化合物を単独または、炭酸ナトリウム、炭酸カリウム等の融剤と共に、共存させることにより、発光性能をより改善した希土類酸化硫化物を得ることができる。
【００３９】
【発明の効果】
本発明は、特定の反応混合物から出発して、有機硫黄酸基を含みナノチューブ構造、ヘキサゴナル構造もしくは層状構造を呈してなる特定構造の希土類酸化物複合体を生成し、この生成した複合体を焼成することにより得るものであり、従来方法で作製したものに比べて、ナノメートルスケールにて厳密に制御された均一な粉末特性を有してなる希土類酸化物粉末を製造することができ、従来法に比し格段に高性能の希土類酸化物を製造できるため、次のような効果が期待できる。
（１）これを演算・メモリ素子用蛍光体として用いた場合、その格子効果により希土類イオンの発光強度が飛躍的に増大し、希土類イオンの室温で永続的ホールバーニング効果に基づく光メモリ・光演算機能の発現に効果的に作用することとなる。
（２）これを蛍光ランプ用蛍光体として用いた場合、その格子効果により希土類イオンの発光強度が飛躍的に増大し、極めて高性能の照明ランプが提供される。
（３）これをカラーテレビブラウン管用蛍光体として用いた場合、その格子効果により希土類イオンの発光強度が飛躍的に増大し、極めて高性能のカラーテレビブラウン管が提供される。
（４）これをプラズマディスプレイ用蛍光体として用いた場合、その格子効果により希土類イオンの発光強度が飛躍的に増大し、極めて高性能のプラズマディスプレイが提供される。
（５）これを酸化還元あるいは酸塩基触媒として用いた場合、活性サイトが均一かつナノメートルスケールで分散しているため、従来の材料に比べて格段に高い触媒効果が発揮し得られ、触媒材料として優れたものとなる。
【図面の簡単な説明】
【図１】（ａ）は実施例１で得られた中間体であるナノチューブ状イットリウム、イッテリビウム、及びルテチウム系酸化物複合体のＸ線回折図。
（ｂ）は、同じくイットリウム系酸化物複合体の透過形電子顕微鏡写真。
【図２】（ａ）は実施例１においてナノチューブ状複合体を前駆体として得られた３％ユーロピウムドープ酸化イットリウム３％Ｅｕ／ＮＴ（Ｙ）及び従来法の均一沈殿法で得られた３％Ｅｕドープ酸化イットリウム３％Ｅｕ／Ｂｕｌｋ（Ｙ）の発光スペクトル。
（ｂ）は、前者試料の透過形電子顕微鏡写真。
【図３】（ａ）は実施例２で得られた中間体であるヘキサゴナル構造型イットリウム系酸化物複合体のＸ線回折図。
（ｂ）は同じく５％Ｅｕドープ試料の透過形電子顕微鏡写真。ヘキサゴナル構造特有のパターンが認められる。
（ｃ）は従来法の均一沈殿法で得られた３％Ｅｕドープ酸化イットリウムの透過形電子顕微鏡写真。バルク状形態が認められる。
【図４】（ａ）は実施例２においてヘキサゴナル構造複合体を前駆体として得られた３％及び５％Ｅｕドープ酸化イットリウムのＸ線回折図。
（ｂ）は同じく５％Ｅｕドープ試料の透過形電子顕微鏡写真である。（ｃ）は、同じく１％、３％及び５％Ｅｕドープ酸化イットリウムと均一沈殿法で得られた３％Ｅｕドープした酸化イットリウムの発光スペクトル（励起波長３９５ｎｍ）。］[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is used as a basic material or functional element for photonics / electronics / information technology such as arithmetic / memory elements, light emitting elements, and sensor elements utilizing the optical and chemical properties of rare earth ions, and as a catalyst for various chemical reactions. The present invention relates to a method for producing a rare earth oxide. In particular, the present invention relates to a method for producing a high-performance rare earth oxide derived from a rare earth oxide composite having a nanotube structure, a hexagonal structure, or a layered structure as a precursor, and a rare earth oxide. Here, the rare earth oxide referred to in the present invention includes not only a high purity rare earth oxide but also one doped with another metal.
[0002]
[Prior art]
Rare earth elements have unique magnetic properties, spectroscopic and chemical properties caused by their 4f electrons, and have been widely used as high-performance magnets, luminescent materials, catalysts and the like. Among them, rare earth oxides (Y, Eu) 2 O 3 And (Y, Eu) of oxide sulfide 2 O 2 S is a representative red phosphor, which is used as a fluorescent lamp and a phosphor for a color television CRT, respectively. In the former, for example, the oxalate coprecipitate formed by adding an aqueous oxalic acid solution to a nitric acid solution of yttrium oxide and europium oxide is calcined at 1200 ° C. 2 O 3 , Eu 2 O 3 , S, Na 2 CO 3 Is calcined at 1100-1300 ° C. to give free Na 2 It is produced by washing and removing S (Yasuo Arai, Material Chemistry of Ceramics, Dai Nippon Tosho, 1988, P300).
[0003]
Many of these phosphor materials have been conventionally used as fine particles having a particle size of about several microns. In recent years, however, the necessity of uniformly dispersing fine powders has increased as electronic components have become smaller and more sophisticated. Rare earth oxides having a small particle size and excellent dispersibility have been demanded (Yoshihiro Nishisu, NIRE News, National Institute for Resources and Environment Technology, January 1995). In addition, it has been pointed out that the function and performance of a material depend not only on the particle shape and size but also on the composition and structure of the base material. (Ginya Adachi, "Chemistry of Rare Earth Elements", Chapter 14, edited by Doujin Kagaku) (1999)].
For this reason, a uniform precipitation method or the like for preparing homogeneous and dense monodispersed fine particles by utilizing the decomposition reaction of urea has been developed, but the conventional technology has only provided spherical or amorphous ultrafine particles. The technology to control the fine structure such as the element distribution in the component material at the nanometer scale has not yet been established.
[0004]
On the other hand, as a method for synthesizing an inorganic substance having a new nanoscale structure, a method for creating mesobolous silica having honeycomb-shaped mesopores of 2 to 8 nm was developed by Mobil in 1993 using a surfactant as a template [C . T. Kresge and 4 others, Nature, 359, p. 710-712 (1992)], and thereafter, by the same method, various mesoporous materials having a skeleton component of various metal oxides and sulfides other than silica and a simple metal were successively synthesized [Toki Kijima et al., J. Soc. Inorg. Mater, 8, p. 3-16 (2001)].
[0005]
Furthermore, recently, this template synthesis method has been applied to the synthesis of inorganic nanotubes, and vanadium oxide [M. E. FIG. Spahr and 5 others, Angew. Chem. Int. Ed, 37, p. 1263-65 (1998)], silica [M. Adachi et al., Langmuir, 15, (1999)], titania [H. J. Imai and 4 others. Mater. Chem, 9, 2971, (1999)].
[0006]
In the meantime, the group of the present inventors also used the dodecyl sulfate ion as a template to form an aluminum-based [M. Yada and 4 others, Inorg. Chem., 36, 5565-69 (1997)], yttrium-based [M. Yada and three others, Inorg. Chem, 37, 6470-75 (1998)], lanthanoids [M. Yada et al., Angew. Chem. Int. Ed, 38, 3506-09 (1999)] and various other hexagonal structure-type oxide mesocomposites and layered structure composites were synthesized [M. Yada et al., Rec Res. Devel. Inorg. Chem, 2, 25-39 (2000)], and the synthesis of rare-earth oxide nanotubes has also been successful [M. Yada and 4 others, Adv. Mater. , 25-39 (2002)].
It has also been found for the first time that rare earth oxides can be made porous by exchanging template ions with acetate ions [see Inorg. Chem, 37, 6470-75 (1998)], Angew. Chem. Int. Ed, 38, 3506-09 (1999)].
[0007]
Each of the inorganic nanostructures obtained using a surfactant as a template has a nanotube, a honeycomb-like or a layered long-period structure, and the constituent atoms constituting the skeleton do not take a regular arrangement like a crystal. It is characterized by having a specific degree of order slightly closer to the crystalline structure [Go Kijima et al. Soc. Inorg. Mater, 8, p. 3-16 (2001)].
[0008]
[Problems to be solved by the invention]
The present invention provides a wide variety of research reports on methods for synthesizing rare earth oxides and inorganic nanostructures introduced and enumerated in the prior art, and nano-structures having novel compositions and structures different from these, while keeping in mind the prior art. It is an object of the present invention to provide a method for producing a rare earth oxide having a novel performance using a structure as an intermediate. In particular, it is an object of the present invention to provide a rare-earth oxide luminous body having excellent luminescence characteristics by effectively incorporating a photoactive rare-earth ion into its skeleton. In addition, it aims to provide new materials that contribute to technological innovation in the fields of electronics, information, and the environment.
[0009]
Among the disclosures in the prior art shown in the above prior art, as a finding related to the present invention, there are reports on rare earth oxides having a long period structure of nanotubes, honeycombs or layers. There is no suggestion or suggestion about a method for producing a rare earth oxide having a novel structure or performance by using these as an intermediate as nothing as to what is or can be introduced as a basic skeleton. Not been. This point is the same in other prior documents.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor has further diligently studied the types of rare earth elements used and the reaction conditions, and as a result, has reached the present invention.
In particular, by using a rare-earth oxide composite having an organic sulfuric acid group as a precursor and having a nanotube-like, honeycomb-like, or layered structure as a precursor, firing by a conventional method provides a much higher performance than that produced by a conventional method. It has been found that rare earth oxides can be produced.
[0011]
That is, as a result of earnest research, the present inventors have succeeded in solving the above-mentioned problems by adopting the technical configurations described in the following (1) to (14).
[0012]
The first solution is (1) a reaction mixture comprising one or more rare earth metal salts, an organic sulfate, urea, and water, or a reaction mixture obtained by adding one or more transition metal salts thereto. A mixture is prepared, and then the reaction mixture is reacted to form a skeleton having a composite oxide containing the rare earth component as a main component, a carbonate group and an organic sulfur acid group as a subcomponent, an outer diameter of about 5 to 7 nm, and an inner diameter of about 5 to 7 nm. A rare earth oxide composite having a nanotube structure of about 2 to 4 nm and a length of 10 nm or more, a hexagonal structure with a lattice constant of 5 to 7 nm, or a layered structure with an interlayer distance of 3 to 6 nm is produced. A calcination treatment is performed at a temperature at which at least the organic sulfur acid group therein is thermally decomposed, or the rare earth oxide complex is reacted with an alcohol solution containing any one of a short-chain organic salt and an inorganic acid salt. , After replacing the organic sulfur acid group in the rare earth oxide complex with the anion in the solution, a calcination treatment is performed at a temperature at which at least the substituted anion group in the rare earth oxide complex is thermally decomposed. Is a method for producing a rare earth oxide.
[0013]
A sixth solution from the second invention is derived from the first solution, and the second solution is that (2) the starting reaction mixture is europium (Eu), gadolinium (Gd). And at least a portion of a lanthanide element containing manganese or copper, whereby a rare earth site in the skeleton is partially doped with the metal, and a composite oxide containing a rare earth component is mainly contained. A nanotube structure having an outer diameter of about 5 to 7 nm, an inner diameter of about 2 to 4 nm, a length of 10 nm or more, a hexagonal structure with a lattice constant of 5 to 7 nm, or an interlayer distance. Producing a rare earth oxide composite having a layered structure of 3 to 6 nm, and then subjecting the rare earth oxide composite to a calcination treatment at a temperature at which at least the organic sulfur acid groups therein are thermally decomposed, Alternatively, the rare earth oxide complex is reacted with an alcohol solution containing any one of a short-chain-length organic acid salt and an inorganic acid salt, and the organic sulfur acid groups in the rare earth oxide complex are shaded in the solution. After the substitution with the ions, a calcination treatment is performed at a temperature at which at least the substituted anion groups in the rare earth oxide composite are thermally decomposed, so that the rare earth sites in the skeleton of the rare earth oxide are partially doped with the metal. The method for producing a rare earth oxide according to the above item (1), wherein at least one of lanthanide elements including europium (Eu) and gadolinium (Gd), or manganese or copper is doped.
[0014]
A third aspect of the present invention is the method for producing a rare earth oxide according to the above item (1), wherein (3) the baking treatment is performed at 450 ° C. or more in an oxidizing atmosphere.
(4) The method for producing a rare earth oxide according to the above (2), wherein the baking treatment is performed in an oxidizing atmosphere at 450 ° C. or higher.
(5) The calcination treatment is performed in an oxidizing atmosphere at a temperature of 600 ° C. or lower before decomposing organic sulfur acid groups or substituted anionic groups constituting the rare earth oxide composite, and then in a reducing atmosphere at a temperature of 600 ° C. or higher. The method for producing a rare earth oxide according to the above item (1), wherein the method is performed by a two-step process by post-firing.
(6) The calcination treatment is performed in an oxidizing atmosphere at a temperature of 600 ° C. or lower before decomposing organic sulfur acid groups or substituted anion groups constituting the rare earth oxide composite, and then in a reducing atmosphere at a temperature of 600 ° C. or higher. The method for producing a rare earth oxide according to the above item (2), wherein the method is performed by a two-step process by post-firing.
[0015]
Seventh to twelfth solutions relate to the rare earth oxide itself obtained by each of the first to sixth manufacturing methods.
That is, (7) a reaction mixture comprising one or more rare earth metal salts, an organic sulfurate, urea, and water, or a reaction mixture obtained by adding one or more transition metal salts thereto, The reaction mixture is reacted to form a skeleton having a composite oxide containing the rare earth component as a main component, a carbonic acid group and an organic sulfuric acid group as subcomponents, an outer diameter of about 5 to 7 nm, an inner diameter of about 2 to 4 nm, and a length of about 2 to 4 nm. A rare earth oxide composite having a nanotube structure of 10 nm or more, a hexagonal structure with a lattice constant of 5 to 7 nm, or a layered structure with an interlayer distance of 3 to 6 nm is produced, and then the rare earth oxide composite is converted into at least organic sulfur. A calcination treatment is performed at a temperature at which the acid group is thermally decomposed, or the rare earth oxide complex is reacted with an alcohol solution containing any one of a short-chain-length organic acid salt and an inorganic acid salt, and the rare earth oxidation is performed. After substituting the organic sulfur acid groups in the composite with the anions in the solution, a calcination treatment is performed at a temperature at which at least the substituted anionic groups in the rare earth oxide composite are thermally decomposed. A rare earth oxide characterized by being obtained.
[0016]
(8) The starting reaction mixture contains at least a part of one of lantinodo elements including europium (Eu) and gadolinium (Gd), or manganese and copper. Is composed of a skeleton containing, as a main component, a composite oxide containing a rare-earth component, which is partially doped with a carbonate group and an organic sulfuric acid group, as an outer diameter of about 5 to 7 nm, an inner diameter of about 2 to 4 nm, and a length of 10 nm. A rare earth oxide composite having the above nanotube structure, a hexagonal structure with a lattice constant of 5 to 7 nm, or a layered structure with an interlayer distance of 3 to 6 nm is produced, and then the rare earth oxide composite is converted into at least an organic sulfuric acid group. The rare earth oxide complex is subjected to a calcination treatment at a temperature at which the compound is thermally decomposed, or the rare earth oxide complex is reacted with an alcohol solution containing one of a short-chain organic salt and an inorganic acid salt. After the organic sulfuric acid group in the rare earth oxide composite is replaced with an anion in the solution, a calcination treatment is performed at a temperature at which at least the substituted anion group in the rare earth oxide composite is thermally decomposed. A lanthanide element containing europium (Eu) and gadolinium (Gd), which is obtained by the above process, obtaining a product in which the rare earth site in the skeleton of the rare earth oxide is partially doped with the metal. Or the rare earth oxide according to the above item (7), which is at least doped with manganese or copper.
[0017]
(9) The rare earth oxide as described in the above item (7), wherein the baking treatment is performed at 450 ° C. or more in an oxidizing atmosphere.
(10) The rare earth oxide as described in the above item (8), wherein the baking treatment is performed in an oxidizing atmosphere at 450 ° C. or higher.
(11) The calcination treatment is performed in an oxidizing atmosphere at a temperature of 600 ° C. or lower before decomposing organic sulfur acid groups or substituted anion groups constituting the rare earth oxide composite, and then in a reducing atmosphere at a temperature of 600 ° C. or higher. The rare earth oxide as described in the above item (7), which is carried out by a two-step process by post-firing.
(12) The calcination treatment is performed in an oxidizing atmosphere at a temperature of 600 ° C. or lower before decomposing organic sulfur acid groups or substituted anion groups constituting the rare earth oxide complex, and then in a reducing atmosphere at a temperature of 600 ° C. or higher. The rare earth oxide according to the above item (8), which is carried out by a two-step process by post-firing.
[0018]
The thirteenth and fourteenth solutions provide the rare earth oxide as a phosphor material and a catalyst material.
That is, a thirteenth solution is (13) a phosphor material using the rare earth oxide described in any one of the above (7) to (12). A fourteenth solution is a catalyst material characterized by (14) using the rare earth oxide according to any one of the above (7) to (12).
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
It is an object of the present invention to provide a method for producing a high-performance rare earth oxide derived from a rare earth oxide composite having a nanotube structure, a hexagonal structure, or a layered structure as a precursor, and a rare earth oxide. As you did. The rare earth oxide complex as the precursor is a nanotube structure with a specific size consisting of one or more specific rare earth metal oxides as a main component, and a skeleton containing a carbonic acid group and an organic sulfuric acid group as subcomponents, and a hexagonal structure. Body or layered structure, and the main components and sub-components are ion-exchanged in addition to the main components and sub-components, which allow various combinations in composition. It contains a very wide variety of combinations, as it is secondarily replaced by other rare earth metal elements, transition metal elements, or other organic or inorganic acid anions by manipulation. Therefore, it goes without saying that the components and structures of the rare earth oxides derived by firing these rare earth oxide composites also include various combinations. Further, the examples presented below are merely examples of the present invention, and the present invention should not be limited by these examples.
[0020]
The rare earth metal salts according to the present invention include scandium (Sc), yttrium (Y), europium (Eu), terbium (Tb), manganese (Mn) such as nitrates and chlorides of lanthanoid elements including gadolinium (Gd), One or more of rare earth metal salts such as nitrates and chlorides of transition metals including copper (Cu) and transition metal salts are used. Of the two or more rare earth metal salts, it is preferable to use nitrate, chloride, or the like of yttrium (Y), ytterbium (Yb), or lutetium (Lu) as one of the two or more rare earth metal salts.
[0021]
Examples of the organic sulfuric acid salt according to the present invention include sodium dodecyl sulfate and sodium dodecylbenzenesulfonate.
[0022]
Examples of the short-chain-length organic acid salt according to the present invention include an acetate, a malonate and the like.
[0023]
Examples of the inorganic acid salt according to the present invention include a periodate salt and a triiodide salt.
[0024]
Hereinafter, the present invention will be described with reference to the drawings and embodiments. However, these examples are shown with specific examples to assist understanding of the present invention, and the present invention is not limited to these examples and is not limited thereto.
[0025]
FIG. 1A is an X-ray diffraction diagram of a nanotube-structured yttrium, ytterbium, and lutetium-based oxide composite which is an intermediate obtained in Example 1 of the present invention. FIG. 1 (b) is a photograph observed by a transmission electron microscope, and it is observed that the rare earth oxide compound of the present invention has a hollow tubular structure. FIG. 2 (a) shows 3% europium-doped
[0026]
FIG. 3A is an X-ray diffraction diagram of the hexagonal structure type yttrium-based oxide composite which is an intermediate obtained in Example 2, and shows each europium (Eu) content. FIG. 3B is a transmission electron micrograph of the same 5% Eu-doped sample, in which a pattern specific to the hexagonal structure is observed. FIG. 3 (c) is a transmission electron micrograph of 3% Eu-doped yttrium oxide obtained by the conventional uniform precipitation method, and a bulk form is recognized.
[0027]
FIG. 4A shows X-ray diffraction diagrams of 3% and 5% Eu-doped yttrium oxide obtained using the hexagonal structure composite as a precursor in Example 2, and FIG. It is a transmission electron microscope photograph of a dope sample. FIG. 4C shows emission spectra (excitation spectra) of the yttrium oxide doped with 1%, 3% and 5% Eu obtained in Example 2 and the yttrium oxide doped with 3% Eu obtained by the uniform precipitation method. FIG. 3 is a diagram showing the comparison of the wavelength (395 nm).
[0028]
Example 1
A reaction mixture was prepared by mixing yttrium nitrate, europium chloride, sodium dodecyl sulfate, urea, and water at a molar ratio of 0.97: 0.03: 2: 30: 60. The obtained reaction mixture was placed in a heated reaction vessel, stirred at 40 ° C. for 1 hour, and reacted at 80 ° C. for 100 hours. A fine solid phase formed in the reaction solution was deposited. This was centrifuged, washed with water, and dried at 40 ° C. to obtain a complex as an intermediate. By the same operation, samples using lutetium nitrate and yttrium lithium nitrate instead of yttrium nitrate were also prepared.
Next, the composite was fired in air at 1000 ° C. for 3 hours to obtain a final product, europium yttrium oxide. Further, a precipitate obtained by a similar reaction without adding a surfactant was fired under the same conditions to obtain an oxide.
First, the complex as an intermediate has an X-ray diffraction characterized by three long-period peaks at d = 6.3 nm, 2.9 nm, and 1.9 nm corresponding to the 001, 002, and 003 diffraction lines of the nanotube structure. A figure was given [FIG. 1 (a)].
In addition, observation with a transmission electron microscope confirmed that the product was a tubular product having an outer diameter of 6 nm and an inner diameter of 3 nm [FIG. 1 (b)]. Further, the presence of a dodecyl sulfate group was confirmed from the infrared absorption (FT-IR) spectrum, and the ratio between the doping amount of Eu and the charged amount determined by EDX was about 58%.
It was confirmed by X-ray diffraction analysis that the obtained fired body had the same crystal structure as yttrium oxide [the diffraction pattern was similar to that of FIG. 4 (a)]. The form of the powder was observed to have a bulk form [FIG. 2 (b)].
FIG. 2A shows the emission spectra of the rare earth oxide obtained by the above method and the rare earth oxide obtained by the conventional method without adding a surfactant. As is clear from the figure, one rare earth oxide according to the present invention shows about twice the emission intensity of the rare earth oxide according to the conventional method, and it is understood that the performance is remarkably improved.
[0029]
Example 2
A reaction mixture was prepared by mixing yttrium nitrate, europium chloride, sodium dodecyl sulfate, urea, and water at a molar ratio of 0.95: 0.05: 2: 30: 60. The obtained reaction mixture was placed in a heated reaction vessel, stirred at 40 ° C for 1 hour, and reacted at 80 ° C for 20 hours. A fine solid phase formed in the reaction solution was deposited. This was centrifuged, washed with water, and dried at 40 ° C. to obtain a complex as an intermediate.
Next, the composite was calcined in air at 1000 ° C. for 5 hours to obtain a final product, europium yttrium oxide. Further, a precipitate obtained by a similar reaction without adding a surfactant was fired under the same conditions to obtain an oxide.
First, from the X-ray diffraction pattern [FIG. 3 (a)] and the transmission electron microscope image [FIG. 3 (b)], the complex as an intermediate is a mesostructure having a hexagonal structure with a lattice constant of 5.4 nm. Here is confirmed. Furthermore, the presence of a dodecyl sulfate group was confirmed from the infrared absorption (FT-IR) spectrum, and the ratio between the doping amount of Eu and the charged amount obtained from EDX obtained from EDX was about 44%. FIG. 3 (c) is a transmission electron micrograph of the Eu-doped yttrium oxide obtained by the conventional precipitation method, in which a bulk form is observed.
The fired body had a bulk shape (FIG. 4 (b)), and it was confirmed from the X-ray diffraction pattern that it had the same crystal structure as yttrium oxide (FIG. 4 (a)). FIG. 4C shows emission spectra of the rare earth oxide obtained by the above-described method and the rare earth oxide obtained by the conventional method without adding a surfactant. Similar to the case where the tubular composite was prepared as an intermediate, the rare-earth oxide obtained through the hexagonal structure composite also showed about twice the emission intensity of the rare-earth oxide obtained by the conventional method, and the performance was remarkable. It can be seen that it has improved.
[0030]
The present invention, in addition to the above examples, has accumulated a wide variety of experimental examples, and as a result of arranging the obtained data, as a result, a precursor of a rare earth oxide composite having an organic sulfuric acid group and having a nanotube structure, a hexagonal structure, or a layered structure was obtained. It has been confirmed that by firing as a body, a rare earth oxide having much higher performance can be produced by firing in a conventional manner than that produced by a conventional method. The reason why the performance of the rare earth oxide according to the present invention is excellent is not clear at present, but by passing through the nanostructure as described above, the uniformity of distribution of europium ions and the like in the rare earth oxide crystal is increased, and as a result, It is assumed that the excitation energy of the element is effectively used for light emission.
[0031]
The present invention has succeeded in developing a novel method for producing a rare earth oxide having a unique crystal structure having a rare earth element, and its industrial significance is extremely large. Disclosure of detailed physical properties, specific characteristics of various properties and effects in various technical fields, etc., and research and development of new technical possibilities and development potentials related to this will be conducted in the future. Although much work has been left to research, it has been entrusted, but it is expected that excellent effects can be achieved in various fields due to its composition and unique crystal structure.
[0032]
In other words, it has various useful functions such as a light conversion element function that is excellent in luminous intensity and luminous efficiency when irradiating ultraviolet light and visible light, and a catalytic function in various reactions, and is expected to be used in various applications expected by the expression of these useful functions It has succeeded in obtaining a rare earth oxide that can be provided.
[0033]
Here, the method for producing the rare earth oxide has been specifically and individually disclosed in the above-mentioned Examples, and the reaction conditions in the production method when the method is carried out from the preparation of the reaction mixture are described and summarized. It is as follows.
First, a method for producing a rare earth oxide composite as an intermediate is as follows: {circle around (1)} One of a metal salt such as nitrate or chloride of yttrium (Y), ytterbium (Yb) or lutetium (Lu), and europium ( Rare earth metal salts and transition metal salts such as transition metal nitrates and chlorides including lanthanoid elements including Eu), terbium (Tb) and gatolinium (Gd), and manganese (Mn) and copper (Cu). A rare earth oxide composite having a nanotube structure, a hexagonal structure, or a layered structure by mixing at least one of the above, an organic sulfurate, urea, and water and reacting them for a predetermined time; and (2) The complex obtained in the preceding paragraph is further reacted with an alcohol solution containing any one of a short-chain organic salt and an inorganic acid salt, and the organic sulfur acid groups in the complex are removed from the solution. It is roughly classified into a method of fabricating a rare earth oxide complex was allowed substituted with ions.
[0034]
The reaction conditions are illustratively summarized as follows.
That is, {circle around (1)} the tube-shaped composite containing yttrium and europium as rare earth components is obtained by mixing sodium dodecyl sulfate with 1 to 3 mol, preferably 2 mol, with respect to 0.95 mol of yttrium nitrate and 0.5 mol of europium nitrate. 20 to 50 moles, preferably 30 moles, and 40 to 80 moles, preferably 60 moles of water, and the mixture was stirred at 40 ° C. for 1 hour, and then stirred at 70 to 85 ° C. for 50 hours or more, preferably 100 ° C. at 80 ° C. Manufacture by holding for a time. {Circle around (2)} The hexagonal structure composite containing yttrium and europium as rare earth components is produced by holding the reaction mixture prepared in the same manner as in {circle around (1)} at 70 to 85 ° C. for 10 to 30 hours, preferably at 80 ° C. for 20 hours. . {Circle around (3)} The layered structure composite containing yttrium and europium as rare earth components is produced by holding the reaction mixture prepared in the same manner as in {circle around (1)} at 70 to 85 ° C. for 3 to 5 hours, preferably at 80 ° C. for 4 hours. .
[0035]
The solid product obtained by the above reactions (1) and (3) is separated from the liquid, washed with water, and dried at 30 to 40 ° C. for 12 to 24 hours to obtain a nanotube structure having a rare earth element as a skeleton component. It is obtained from a composite having a hexagonal structure and a layered structure. Each of these compounds has a tubular structure having an outer diameter of about 6 nm and an inner diameter of 3 nm, a hexagonal structure having a lattice constant of 6 nm, an interlayer distance of about 6 nm in which a carbon group and an organic sulfuric acid group (alkyl sulfate group) are incorporated in a rare earth oxide skeleton. It was found to have a layered structure of 4 nm.
[0036]
Further, by reacting the organic sulfur acid group (alkyl sulfate group) -containing tube compound of each complex with an organic acid such as acetic acid or malonic acid, or an alcohol solution containing an inorganic acid such as periodate or triiodide compound ion. The site of the organic sulfur acid group in the compound is contained in the alcohol solution.
As described above, rare earth oxide nanotubes substituted by organic acid ions and inorganic acid ions can be obtained.
The reaction conditions in the production method by this substitution will be exemplarily mentioned and summarized below. For example, 0.5 g of an alkyl sulfate group-containing tubular compound is dispersed in 40 ml of a 0.05 mol / l solution of sodium acetate in ethanol and reacted at 40 ° C. for 1 hour to form an alkyl sulfate ion in the matrix and an acetate ion in the external solution. Anion exchange occurs with the inner diameter of the tube, and the inner diameter of the tube increases from about 2.5 nm before the ion exchange treatment to about 3 nm, whereby the target product can be produced. An ion-substituted product can be obtained by the same treatment for the alkyl sulfate group-containing hexagonal structure compound and the alkyl sulfate group-containing layer structure compound.
[0037]
Next, each of the obtained composites having the nanotube structure, the hexagonal structure and the layered structure is pre-baked in an oxidizing atmosphere at 450 to 600 ° C., preferably 500 ° C. for 1 to 10 hours. Further, post-baking is performed at least at 800 ° C. or more, preferably at 1000 to 1200 ° C., to obtain a rare earth oxide.
[0038]
In addition, at the stage of post-firing, a rare-earth oxysulfide having more improved luminous performance can be obtained by coexisting a sulfur-containing compound alone or with a flux such as sodium carbonate and potassium carbonate.
[0039]
【The invention's effect】
The present invention produces a rare-earth oxide composite having a specific structure starting from a specific reaction mixture and having a nanotube structure, a hexagonal structure or a layered structure containing an organic sulfuric acid group, and firing the formed composite. In this case, a rare-earth oxide powder having uniform powder properties strictly controlled on a nanometer scale can be produced as compared with those produced by a conventional method. Since a very high performance rare earth oxide can be produced as compared with the method described above, the following effects can be expected.
(1) When this is used as a phosphor for an arithmetic / memory element, the light emission intensity of the rare-earth ion is dramatically increased by its lattice effect, and an optical memory / optical arithmetic function based on a permanent hole burning effect of the rare-earth ion at room temperature. Effectively act on the expression of
(2) When this is used as a phosphor for a fluorescent lamp, the luminous intensity of rare-earth ions is dramatically increased by the lattice effect, and an extremely high-performance illumination lamp is provided.
(3) When this is used as a phosphor for a color television cathode ray tube, the emission effect of rare earth ions is dramatically increased by the lattice effect, and an extremely high performance color television cathode ray tube is provided.
(4) When this is used as a phosphor for a plasma display, the emission effect of rare earth ions is dramatically increased by the lattice effect, and an extremely high-performance plasma display is provided.
(5) When this is used as an oxidation-reduction or acid-base catalyst, the active sites are uniform and dispersed on a nanometer scale, so that a remarkably higher catalytic effect can be exhibited as compared with conventional materials. Will be excellent.
[Brief description of the drawings]
FIG. 1A is an X-ray diffraction diagram of a nanotube-like yttrium, ytterbium, and lutetium-based oxide composite as an intermediate obtained in Example 1.
(B) is a transmission electron micrograph of the yttrium-based oxide composite.
FIG. 2 (a) shows 3% europium-doped
(B) is a transmission electron micrograph of the former sample.
FIG. 3 (a) is an X-ray diffraction diagram of a hexagonal structure type yttrium-based oxide composite which is an intermediate obtained in Example 2.
(B) is a transmission electron micrograph of the same 5% Eu-doped sample. A pattern peculiar to the hexagonal structure is observed.
(C) is a transmission electron micrograph of 3% Eu-doped yttrium oxide obtained by a conventional uniform precipitation method. A bulk form is observed.
FIG. 4 (a) is an X-ray diffraction diagram of 3% and 5% Eu-doped yttrium oxide obtained using a hexagonal structure composite as a precursor in Example 2.
(B) is a transmission electron micrograph of the same 5% Eu-doped sample. (C) is an emission spectrum (excitation wavelength: 395 nm) of 1%, 3%, and 5% Eu-doped yttrium oxide and 3% Eu-doped yttrium oxide obtained by a uniform precipitation method. ]
Claims (14)
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| JP2007238879A (en) * | 2006-03-13 | 2007-09-20 | National Institute Of Advanced Industrial & Technology | Phosphor material and method for producing the same |
| CN100348496C (en) * | 2004-09-15 | 2007-11-14 | 北京有色金属研究总院 | Low bulk specific weight and large specific surface rare-earth oxide REO and its preparing method |
| JP2008037961A (en) * | 2006-08-03 | 2008-02-21 | National Institute Of Advanced Industrial & Technology | Sheet-like fluorescent particle and method for producing the same |
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| CN100348496C (en) * | 2004-09-15 | 2007-11-14 | 北京有色金属研究总院 | Low bulk specific weight and large specific surface rare-earth oxide REO and its preparing method |
| JP2007238879A (en) * | 2006-03-13 | 2007-09-20 | National Institute Of Advanced Industrial & Technology | Phosphor material and method for producing the same |
| JP2008037961A (en) * | 2006-08-03 | 2008-02-21 | National Institute Of Advanced Industrial & Technology | Sheet-like fluorescent particle and method for producing the same |
| JP2009184869A (en) * | 2008-02-06 | 2009-08-20 | National Institute For Materials Science | Method for producing layered rare earth hydroxide |
| JP2013163621A (en) * | 2012-02-13 | 2013-08-22 | Nissan Motor Co Ltd | Oxide-ion-conductive oxide nanosheet, manufacturing method for oxide-ion-conductive oxide nanosheet, and electrolyte for solid-oxide fuel cell |
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| JP2017036189A (en) * | 2015-08-11 | 2017-02-16 | 国立大学法人島根大学 | Manufacturing method of nanoparticles of rare earth oxide |
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