CN108129153A - A kind of multicomponent rare earth boride（LaxSr1-x）B6Polycrystalline cathode material and preparation method thereof - Google Patents

A kind of multicomponent rare earth boride（LaxSr1-x）B6Polycrystalline cathode material and preparation method thereof Download PDF

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CN108129153A
CN108129153A CN201711463453.8A CN201711463453A CN108129153A CN 108129153 A CN108129153 A CN 108129153A CN 201711463453 A CN201711463453 A CN 201711463453A CN 108129153 A CN108129153 A CN 108129153A
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temperature rise
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周身林
周奕
樊后坤
刘世粮
叶子飘
胡强林
罗小兵
余晓光
温玉锋
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Jinggangshan University
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Abstract

A kind of multicomponent rare earth boride (LaxSr1‑x)B6The preparation method of polycrystalline cathode material belongs to rare earth, alkaline earth hexaboride cathode material technical field.The composition of multielement rare earth hexaboride provided by the present invention is (LaxSr1‑x)B6, wherein, 0.1≤x≤0.9.Method provided by the present invention is with La2O3, SrO and B powder be raw material, using ball milling, vacuum hotpressing reaction-sintered, 1,500 1800 DEG C of maximum sintering temperature synthesizes (LaxSr1‑x)B6Solid solution.Powder synthesis and two processes of sintering densification are combined into one by this method, simplify preparation flow, are helped to reduce sintering temperature, are improved purity and consistency, reduce production cost, are suitble to industrial production and application.(the La that the present invention obtainsxSr1‑x)B6Solid solution polycrystal has the characteristics that single-phase, high fine and close, high emission performance, can be widely used in multiple cathode fields.

Description

A kind of multicomponent rare earth boride (LaxSr1-x)B6Polycrystalline cathode material and preparation method thereof
Technical field
The invention belongs to rare earth, alkaline earth hexaboride cathode material technical fields, and in particular to one kind (LaxSr1-x)B6Gu Solution polycrystal and preparation method thereof.
Background technology
Cathode is the heart device of various Modern vacuum electronic equipments, has in national defense industry, civil field and widely should With.Electron emission source of the hot cathode as vacuum electron device plays vital work to the performance of HIGH-POWERED MICROWAVES device With, be widely used in various high-power pulsed ion beams, particularly in the military equipments such as satellite, radar using be even more day Become ripe.
Lanthanum hexaboride (LaB6) be the hot cathode material haveing excellent performance, have high current emission density, the long-life, it is anti-in The advantages that poison, chemical stability height, resistance to ion bombardment, there are important research meaning and application value.LaB6Militarily purposes is very Extensively, it is mainly commonly utilized on radar, existing radar range finding is too near, it is difficult to meet modern war requirement, be badly in need of replacing big Power tube.Plasma engine and propeller are additionally operable to, is to generate Artificial plasma and space in near-earth spherical space Cosmos airship Electrostatic Control and design.
With technology and economic rapid development, at present on the one hand electron beam technology and equipment develop to micro-electron beam, separately On the one hand develop to high power, requirements at the higher level have been researched and proposed to cathode material.Cathode needs to further improve emission current close Degree reduces operating temperature, extends working life etc..Therefore, at this stage to improve cathode performance research emphasis focus on how Reduce the work function of material.
In the recent period, domestic and foreign scholars have carried out the research of composite multi-component rare-earth hexboride compound cathode material, main Research Thinking It is to LaB6In La carry out other rare earth doped replacements, to reduce work function.These researchs achieve certain progress, but It is all kinds of existing LaB compared with the low-temperature cathodes such as barium tungsten6The work function of Quito member rare-earth hexboride compound cathode is still bigger than normal, work Temperature drift.Therefore to expand its application in wider field (including middle low temperature field), it is also necessary to further reduce work( Function improves emitting performance.
Studies have found that when by LaB6With alkaline earth boride such as SrB6Or BaB6When mixing, thermoelectron hair Penetrate performance ratio LaB6More preferably, which results in people to the research interest of multielement rare earth, alkaline earth hexaboride.In the recent period, apply People is using first-principles calculations Sr doping LaB6Work function, the study found that (the La of certain specific componentsxSr1-x)B6Such as (La0.6Sr0.4)B6With LaB6Compared to lower work function and higher hot-electron emission property.This shows that suitable Sr mixes It is miscellaneous to be expected to reduce LaB6Cathode operating temperature simultaneously greatly improves its hot-electron emission property.SrB6Itself have compared with low work function, LaB6Middle doping Sr substitutes part La other than it can improve emitting performance, moreover it is possible to greatly improve resistivity, contribute to six boronations Object cathode is in the application in direct-heated cathode field.Therefore, regulate and control LaB by adulterating the unordered alternative dopings La of Sr6Crystal knot Structure, the excellent multicomponent rare earth boride (La of processabilityxSr1-x)B6Solid solution polycrystalline cathode, so as to fulfill cathode material performance It is controllable, improve emission properties be of great significance.
At present, the traditional preparation methods of multi-element metal hexaboride, including powder synthesis and two processes of sintering densification. Wherein, the synthetic method of powder mainly has elementsynthesis, boron carbide method, boron thermal reduction method etc..The powder that elementsynthesis obtains Last purity highest, but it is expensive due to boron powder, and metal Sr powder is oxidizable, and Sr is different from the high-temperature vapour pressure of B, so should Method technique is stringent, and equipment requirement is high, and technique is difficult to control, and is unsuitable for large-scale industrial production.The boron prepared using boron carbide method The purity of compound powder is relatively low, but B4The purer boron of price of C is much lower, synthesized powder morphology and raw material B4C has very big Relationship has hard aggregation, lamination.Therefore it is relatively common rare-earth hexboride compound powder to be prepared using boron thermal reduction method at present.
The densification of powder mainly uses hot pressed sintering or discharge plasma sintering (SPS) method.Boride is at high temperature With high chemism and low plasticity, densification process has very big technology difficulty.Hot pressed sintering prepares sintering temperature High (2000-2200 DEG C), leads to that product grains are coarse, hole is more, and consistency is low (relative density is generally below 90%), influences material The mechanics and emitting performance of material cause product to be difficult to apply in the industrial production.SPS is a kind of Fast Sintering technology, but should Method is to equipment requirement height, and yield is low, is not suitable for the industrialized production of product.
A kind of LaB is disclosed in the Chinese patent application of Publication No. 201210331645.46The synthetic method of powder, This method includes the following steps：Using Whote-wet method flow and closed cycle, i.e., using magnesium powder, lanthana powder and boron oxide powder as original Material, chooses suitable composition proportion, base is pressed into after ball milling is sufficiently mixed, in combustion synthesis reaction kettle under protective atmosphere Interior reaction generation is containing LaB6Block material, through mechanical crushing and pulverize it is last, carry out hydrometallurgy, i.e., leached through persalt Reaction makes wherein impurity enter liquid phase, and LaB6Powder exists with solid phase form, carries out separation of solid and liquid using Suction filtration device, obtains LaB6Powder, in drying box low temperature drying obtain finished product.
A kind of LaB is disclosed in the Chinese patent application of Publication No. 201310492257.96The preparation side of polycrystal Method.This method includes the following steps：Shove charge will be equipped with LaB6The mold of powder is placed in sintering furnace；Heating, is divided into four-stage Temperature is gradually increased to predetermined temperature from room temperature；Stop pressure and slow cooling, obtain LaB6Polycrystal.To LaB6Polycrystalline block system For standby, this method does not include the synthesis of powder, is only the second step in conventional two-step, is only by raw material LaB6It is powder sintered The process of densification.Sintering temperature is higher, and the density of product is not high, and relative density is only 92-96%.
A kind of multicomponent rare earth boride is disclosed in the Chinese patent application of Publication No. 200810225029 (LaxRE1-x)B6Cathode material and preparation method thereof, wherein RE are second of rare earth element in addition to La in light rare earth elements (i.e. RE is any one element in Ce, Pr, Nd, Sm, Eu and Gd).This method includes the following steps：1) it is dilute with simple substance respectively Earth metal lanthanum block and RE blocks are raw material, in hydrogen, argon atmospher, using DC arc-plasma evaporation condensation method, prepare LaH respectively2Nanometer Powder and REH2Nanometer powder.2) LaH that step 1) is prepared2Nanometer powder, REH2Nanometer powder and raw material B nano powders Under hypoxemia ar gas environment, grinding is mixed and is packed into graphite jig, is placed in SPS sintering cavities at end, applies the axial pressure of 50MPa Power is sintered under the vacuum condition of argon gas atmosphere or vacuum degree better than 8Pa, and sintering temperature is 1300-1700 DEG C, keeps the temperature 10min After cool to room temperature with the furnace.This method prepares (LaxRE1-x)B6Polycrystalline needs two steps in total：First condensed using arc evaporation Method prepares rare earth nano powder, then obtains polycrystalline bulk using SPS sintering densifications.Preparation process complex process, technology are difficult Degree is big, and equipment is expensive, high energy consumption, and raw material need to use high purity elemental rare earth metal, of high cost, yield is low, is not suitable for industry metaplasia Production.
A kind of high densification (La is disclosed in the Chinese patent application of Publication No. 201510213310.6xCa1-x)B6It is more Brilliant cathode material and preparation method thereof.The invention is with LaB6And CaB6Powder is raw material, using ball milling, hot pressed sintering, is prepared (LaxCa1-x)B6Solid solution polycrystal.This method can prepare (LaxCa1-x)B6Solid solution, but since raw material is two kinds of metals six Boride to be dissolved in sintering, needs very high sintering temperature, maximum sintering temperature is 1700-1900 DEG C, to sintering Stove is more demanding, inconvenient to be applied to production.
Invention content
In order to improve LaB6The emitting performance of polycrystalline cathode material, and solve existing multi-element metal hexaboride polycrystalline system The deficiency of Preparation Method, the present invention provide a kind of multicomponent rare earth boride (LaxSr1-x)B6Polycrystalline cathode material and preparation method thereof. The composition of multielement rare earth hexaboride provided by the present invention is (LaxSr1-x)B6, wherein, 0.1≤x≤0.9.The present invention is carried The method of confession is with La2O3, SrO and B powder be raw material, using ball milling, vacuum hotpressing reaction-sintered, maximum sintering temperature 1500- 1800 DEG C, synthesize (LaxSr1-x)B6Solid solution.Powder synthesis and two processes of sintering densification are combined into one by this method, are simplified Preparation flow helps to reduce sintering temperature, improves purity and consistency, reduce production cost, is suitble to industrial production and application. (the La obtained according to preparation method provided by the inventionxSr1-x)B6Solid solution polycrystal has single-phase, high fine and close, high emission The characteristics of energy, multiple cathode fields can be widely used in.
It is an aspect of the invention to provide a kind of multielement rare earth hexaboride (LaxSr1-x)B6Solid solution polycrystal Preparation method.The preparation method is as follows：
1) batch mixing is matched：
According to reaction equation
xLa2O3+2(1-x)SrO+(14+x)B----2(LaxSr1-x)B6+(x+2)BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, select stainless steel Ball or agate ball are as abrasive media.Ball grinder from glove box is taken out and is fitted into high energy ball mill after ball milling 2-4h in gloves It is sampled in case.
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite mo(u)ld is packed into glove box Tool, mold is placed in hot-pressed sintering furnace；
It is argon gas atmosphere in step 1) and step 2), in the glove box；
3) heating sintering, the first heating stage：Room temperature is to 400-500 DEG C；Second temperature rise period：From the 400- of first stage 500 DEG C are warming up to 700-800 DEG C；The third temperature rise period：1100-1200 DEG C is warming up to from the 700-800 of second stage；4th liter Thermophase：1500-1800 DEG C is warming up to from 1100-1200 DEG C of the phase III.The heating rate of first to third temperature rise period It it is 10-15 DEG C/min, the 4th temperature rise period heating rate is 5-10 DEG C/min.Wherein the first heating stage and the second heating rank Section applies powder 10-15Mpa axial compressive forces, and the third temperature rise period applies 15-20Mpa axial compressive forces to powder；4th heating Stage applies 20-30Mpa axial compressive forces to powder；
4) it keeps the temperature, the 1500-1800 DEG C of temperature 2-4h after the heating of step 3) fourth stage；And in insulating process 30-50Mpa axial compressive forces are applied to powder；
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains (the Lax Sr1-x)B6Solid solution polycrystalline Body.
Preferably, the La described in step 1)2O3With the purity of SrO raw material powder purity >=99.9%, B raw material powders >= 99.0%, particle size range is 1-100 μm.But the present invention is not limited to the La2O3 and SrO of above-mentioned raw materials, different purity and grain size And other rare earths, alkaline earth metallic oxide powder end are applicable to the present invention.
Preferably, in step 1) and step 2), oxygen content and vapour content are equal in argon gas atmosphere in the glove box ≤50ppm。
Preferably, the heating rate of each temperature rise period described in step 3) is 5-10 DEG C/min.
Preferably, in the step 3) before sintering, forvacuum is to air pressure≤2 × 10 in the hot pressing furnace-2Pa。
It is another aspect of the invention to provide a kind of single-phase, high densification (LaxSr1-x)B6Solid solution polycrystalline cathode material Material, wherein, 0.1≤x≤0.9.The cathode material includes (La prepared by the above methodxSr1-x)B6Polycrystal, it is using the present invention (La obtained by methodxSr1-x)B6Solid solution polycrystalline relative density is 98.23-99.81%, has outstanding emitting performance, can be full Requirement of the various electron-emitting devices of foot to cathode performance, by this (LaxSr1-x)B6Polycrystalline processing can obtain required shape and ruler Very little cathode.
Compared with prior art, the present invention has the following advantages：
1) the method for the present invention uses vacuum hotpressing reaction-sintered by La2O3, SrO and B raw material powders be prepared into (LaxSr1-x) B6Polycrystalline is combined into one powder synthesis and two processes of sintering densification.Preparation flow is simplified, reduces sintering temperature, work Skill is simple, easy to operate.
2) using La2O3, SrO and B powder be raw material, reduce production cost, be suitble to industrial production and application, be conducive to Expand the application field of rare earth, alkaline earth hexaboride in terms of cathode material.
3) (the La of synthesisxSr1-x)B6Solid solution polycrystalline cathode material has high-purity, high-compactness and outstanding emissivity Energy.(the La preparedxSr1-x)B6Single hexaboride phase is detected as through X-ray diffraction, relative density reaches as high as 99.81%. Emitting performance test shows (La0.9Sr0.1)B6Cathode saturation emission electric current at a temperature of 1400 DEG C, 1500 DEG C and 1600 DEG C is close Angle value reaches 25.34A/cm respectively2、 37.61/cm2And 62.50A/cm2, there is stronger application prospect.
Description of the drawings
(La prepared by Fig. 1, embodiment 10.3Sr0.7)B6Polycrystalline XRD spectra.
(La prepared by Fig. 2, embodiment 20.4Sr0.6)B6Polycrystalline XRD spectra.
(La prepared by Fig. 3, embodiment 30.7Sr0.3)B6Polycrystalline XRD spectra.
(La prepared by Fig. 4, embodiment 40.8Sr0.2)B6Polycrystalline XRD spectra.
(La prepared by Fig. 5, embodiment 50.9Sr0.1)B6Polycrystalline XRD spectra.
Specific embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described, but protection scope of the present invention is unlimited In following embodiments.Below with reference to attached drawing, the present invention will be described in detail in conjunction with the embodiments, in the absence of conflict, this Shen Please in embodiment and embodiment in feature can be combined with each other.High energy ball mill rotating speed is 400-600r/min, in example Take 500r/min.
Raw material states La in the embodiment of the present invention2O3With the purity of SrO raw material powder purity >=99.9%, B raw material powders >= 99.0%, the particle size range of raw material powder is 1-100 μm.
Embodiment 1
1) according to reaction equation
0.3La2O3+1.4SrO+14.3B----2(La0.3Sr0.7)B6+2.3BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, with stainless steel ball As abrasive media, ball is 10 with powder quality ratio：1.Ball grinder from glove box is taken out and is fitted into ball milling in high energy ball mill It is sampled in glove box after 2h.
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite mo(u)ld is packed into glove box Tool, mold is placed in hot-pressed sintering furnace.
Be argon gas atmosphere in the glove box in step 1) and step 2), oxygen content and vapour content≤ 10ppm；The La2O3It is 99.0% with purity that SrO raw material powders purity is 99.99%, B raw material powders.
3) heating sintering, forvacuum to air pressure is 1 × 10 in hot pressing furnace before sintering-2Pa.The first heating stage：Room temperature is extremely 500℃；Second temperature rise period：800 DEG C are warming up to from 500 DEG C；The third temperature rise period：1200 DEG C are warming up to from 800；4th heating Stage：1200 DEG C are warming up to 1800 DEG C.The heating rate of first to third temperature rise period is 10 DEG C/min, the 4th temperature rise period Heating rate is 5 DEG C/min.Wherein the first heating stage and the second temperature rise period apply 10MPa axial compressive forces, third to powder Temperature rise period applies powder 20MPa axial compressive forces, and the 4th temperature rise period applied 30MPa axial compressive forces to powder.
4) it keeps the temperature, 1800 DEG C of temperature 2h after the heating of step 3) fourth stage；And powder is applied in insulating process Add 30MPa axial compressive forces.
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains single-phase densification (La0.3Sr0.7)B6Solid solution Polycrystal.
(La0.3Sr0.7)B6XRD is surveyed after grinding and polishing, and the results are shown in Figure 1, and as seen from the figure, sample is single-phase for hexaboride, spreads out Penetrate peak intensity height, well-crystallized.(La is measured using electronics specific gravity balance0.3Sr0.7)B6The relative density of polycrystal is 99.81%.
Embodiment 2
1) according to reaction equation
0.4La2O3+1.2SrO+14.4B----2(La0.4Sr0.6)B6+2.4BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, made with agate ball For abrasive media, ball is 15 with powder quality ratio：1.Ball grinder is taken out to be fitted into high energy ball mill from glove box and carries out ball It is sampled in glove box after mill 4h.
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite mo(u)ld is packed into glove box Tool, mold is placed in hot-pressed sintering furnace.
Be argon gas atmosphere in the glove box in step 1) and step 2), oxygen content and vapour content≤ 50ppm；The La2O3It is 99.0% with purity that SrO raw material powders purity is 99.99%, B raw material powders.
3) heating sintering, forvacuum to air pressure is 8.5 × 10 in hot pressing furnace before sintering-3Pa.The first heating stage：Room temperature To 400 DEG C；Second temperature rise period：700 DEG C are warming up to from 400 DEG C；The third temperature rise period：1100 DEG C are warming up to from 700；4th liter Thermophase：1100 DEG C are warming up to 1500 DEG C.The heating rate of first to third temperature rise period is 10 DEG C/min, the 4th heating rank Section heating rate is 5 DEG C/min.Wherein the first heating stage and the second temperature rise period apply powder 15MPa axial compressive forces, the Three temperature rise periods applied powder 20MPa axial compressive forces, and the 4th temperature rise period applied 20MPa axial compressive forces to powder
4) it keeps the temperature, 1500 DEG C of temperature 4h after the heating of step 3) fourth stage；And powder is applied in insulating process Add 50MPa axial compressive forces.
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains single-phase densification (La0.4Sr0.6)B6Solid solution Polycrystal.
(La0.4Sr0.6)B6XRD is surveyed after grinding and polishing, and the results are shown in Figure 2, and as seen from the figure, sample is single-phase for hexaboride, spreads out Penetrate peak intensity height, well-crystallized.(La is measured using electronics specific gravity balance0.4Sr0.6)B6The relative density of polycrystal is 99.46%.This example demonstrates that (the La of high quality can be also prepared under 1500 DEG C of sintering temperaturesxSr1-x)B6Solid solution is more Brilliant cathode material, greatly reduces sintering temperature.
Embodiment 3
1) according to reaction equation
0.7La2O3+0.6SrO+14.7B----2(La0.7Sr0.3)B6+2.7BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, with stainless steel ball For abrasive media, ball is 20 with powder quality ratio：1.Ball grinder from glove box is taken out and is fitted into ball milling 3h in high energy ball mill It is sampled in glove box afterwards.
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite mo(u)ld is packed into glove box Tool, mold is placed in hot-pressed sintering furnace.
Be argon gas atmosphere in the glove box in step 1) and step 2), oxygen content and vapour content≤5ppm； The La2O3It is 99.0% with purity that SrO raw material powders purity is 99.99%, B raw material powders.
3) heating sintering, forvacuum to air pressure is 8.8 × 10 in hot pressing furnace before sintering-3Pa.The first heating stage：Room temperature To 500 DEG C；Second temperature rise period：800 DEG C are warming up to from 500 DEG C；The third temperature rise period：1200 DEG C are warming up to from 800；4th liter Thermophase：1200 DEG C are warming up to 1700 DEG C.The heating rate of first to third temperature rise period is 10 DEG C/min, the 4th heating rank Section heating rate is 10 DEG C/min.Wherein the first heating stage and the second temperature rise period apply 10MPa axial compressive forces to powder, The third temperature rise period applies 20MPa axial compressive forces to powder；4th temperature rise period applied 20MPa axial compressive forces to powder.
4) it keeps the temperature, 1700 DEG C of temperature 2h after the heating of step 3) fourth stage；And powder is applied in insulating process Add 40MPa axial compressive forces；
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains single-phase densification (La0.7Sr0.3)B6Solid solution Polycrystal.
(La0.7Sr0.3)B6XRD is surveyed after grinding and polishing, and the results are shown in Figure 3, and as seen from the figure, sample is single-phase for hexaboride, spreads out Penetrate peak intensity height, well-crystallized.(La is measured using electronics specific gravity balance0.7Sr0.3)B6The relative density of polycrystal is 98.23%.
Embodiment 4
1) according to reaction equation
0.8La2O3+0.4SrO+14.8B----2(La0.8Sr0.2)B6+2.8BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, with stainless steel ball For abrasive media.Ball grinder is taken out to be fitted into high energy ball mill after ball milling 2h from glove box and is sampled in glove box.
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite mo(u)ld is packed into glove box Tool, mold is placed in hot-pressed sintering furnace；
Be argon gas atmosphere in the glove box in step 1) and step 2), oxygen content and vapour content≤3ppm； The La2O3It is 99.0% with purity that SrO raw material powders purity is 99.99%, B raw material powders.
3) heating sintering, forvacuum to air pressure is 9.1 × 10 in hot pressing furnace before sintering-3Pa.The first heating stage：Room temperature To 500 DEG C；Second temperature rise period：800 DEG C are warming up to from 500 DEG C；The third temperature rise period：1200 DEG C are warming up to from 800；4th liter Thermophase：1200 DEG C are warming up to 1800 DEG C.The heating rate of first to third temperature rise period is 15 DEG C/min, the 4th heating rank Section heating rate is 5 DEG C/min.Wherein the first heating stage and the second temperature rise period apply powder 10MPa axial compressive forces, the Three temperature rise periods applied powder 20MPa axial compressive forces, and the 4th temperature rise period applied 20MPa axial compressive forces to powder；
4) it keeps the temperature, 1800 DEG C of temperature 2h after the heating of step 3) fourth stage；And powder is applied in insulating process Add 30MPa axial compressive forces；
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains single-phase densification (La0.8Sr0.2)B6Solid solution Polycrystal.
(La0.8Sr0.2)B6XRD is surveyed after grinding and polishing, and the results are shown in Figure 4, and as seen from the figure, sample is single-phase for hexaboride, spreads out Penetrate peak intensity height, well-crystallized.(La is measured using electronics specific gravity balance0.8Sr0.2)B6The relative density of polycrystal is 98.59%.
Embodiment 5
1) according to reaction equation
0.9La2O3+0.2SrO+14.9B----2(La0.9Sr0.1)B6+2.9BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, with stainless steel ball For abrasive media.Ball grinder is taken out to be fitted into high energy ball mill after ball milling 2h from glove box and is sampled in glove box.
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite mo(u)ld is packed into glove box Tool, mold is placed in hot-pressed sintering furnace；
Be argon gas atmosphere in the glove box in step 1) and step 2), oxygen content and vapour content≤5ppm； The La2O3It is 99.0% with purity that SrO raw material powders purity is 99.99%, B raw material powders.
3) heating sintering, forvacuum to air pressure is 9.6 × 10 in hot pressing furnace before sintering-3Pa.The first heating stage：Room temperature To 500 DEG C；Second temperature rise period：800 DEG C are warming up to from 500 DEG C；The third temperature rise period：1200 DEG C are warming up to from 800；4th liter Thermophase：1200 DEG C are warming up to 1800 DEG C.The heating rate of first to third temperature rise period is 10 DEG C/min, the 4th heating rank Section heating rate is 5 DEG C/min.Wherein the first heating stage and the second temperature rise period apply powder 10MPa axial compressive forces, the Three temperature rise periods applied powder 20MPa axial compressive forces, and the 4th temperature rise period applied 20MPa axial compressive forces to powder；
4) it keeps the temperature, 1800 DEG C of temperature 2h after the heating of step 3) fourth stage；And powder is applied in insulating process Add 30MPa axial compressive forces；
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains single-phase densification (La0.9Sr0.1)B6Solid solution Polycrystal.
(La0.9Sr0.1)B6XRD is surveyed after grinding and polishing, and the results are shown in Figure 5, and as seen from the figure, sample is single-phase for hexaboride, spreads out Penetrate peak intensity height, well-crystallized.(La is measured using electronics specific gravity balance0.9Sr0.1)B6The relative density of polycrystal is 99.65%.
More than each (La for preparing of 5 embodimentsxSr1-x)B6Emission p erformance is tested：At 1400 DEG C, 1500 DEG C and Saturation emission current density value reaches 20.2-26.7A/cm respectively at a temperature of 1600 DEG C2, 29.6-37.5/cm2And 55.4-66.8A/ cm2, there is good emitting performance and very strong application prospect.

Claims (5)

1. a kind of multicomponent rare earth boride (LaxSr1-x)B6The preparation method of polycrystalline cathode material, which is characterized in that the preparation side Method specific steps include as follows：
1) batch mixing is matched：
According to reaction equation
xLa2O3+2(1-x)SrO+(14+x)B----2(LaxSr1-x)B6+(x+2)BO↑
In glove box, La is weighed respectively2O3, SrO and B raw material powders, be fitted into stainless-steel grinding tank, select stainless steel ball or Agate ball is as abrasive media；Ball grinder from glove box is taken out and is fitted into high energy ball mill after ball milling 2-4h in glove box Sampling；
2) shove charge, the La that step 1) ball milling is mixed evenly2O3, SrO and B raw material powders graphite jig is packed into glove box, will Mold is placed in hot-pressed sintering furnace；
It is argon gas atmosphere in step 1) and step 2), in the glove box；
3) heating sintering, the first heating stage：Room temperature is to 400-500 DEG C；Second temperature rise period：From the 400-500 of first stage DEG C it is warming up to 700-800 DEG C；The third temperature rise period：1100-1200 DEG C is warming up to from the 700-800 of second stage；4th heating Stage：1500-1800 DEG C is warming up to from 1100-1200 DEG C of the phase III；The heating rate of first to third temperature rise period is 10-15 DEG C/min, the 4th temperature rise period heating rate is 5-10 DEG C/min；Wherein the first heating stage and the second temperature rise period Apply 10-15MPa axial compressive forces to powder, the third temperature rise period applies powder 15-20MPa axial compressive forces, the 4th heating rank Section applies 20-30MPa axial compressive forces to powder；
4) it keeps the temperature, the 1500-1800 DEG C of temperature 2-4h after the heating of step 3) fourth stage；And in insulating process to powder Apply 30-50MPa axial compressive forces；
5) cool down, step 4) heat preservation terminates recession pressure, cools down with furnace cooling, obtains (the LaxSr1-x)B6Solid solution polycrystal.
2. according to method of claim 1, which is characterized in that the purity of La2O3 and SrO raw material powders described in step 1) >= Purity >=99.0% of 99.9%, B raw material powder, particle size range are 1-100 μm；
In step 1) and step 2), in the glove box in argon gas atmosphere oxygen content and vapour content≤50ppm.
3. according to method of claim 1, which is characterized in that in step 3) before sintering, forvacuum in the hot pressing furnace To air pressure≤2 × 10-2Pa。
4. (the La that the either method according to claim 1-3 is preparedxSr1-x)B6Polycrystal.
5. (the La that the either method according to claim 1-3 is preparedxSr1-x)B6Application of the polycrystal as cathode material.
CN201711463453.8A 2017-12-28 2017-12-28 Multicomponent rare earth boride (La)xSr1-x)B6Polycrystalline cathode material and preparation method thereof Active CN108129153B (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111285380A (en) * 2020-02-04 2020-06-16 天津包钢稀土研究院有限责任公司 Preparation method and application of multi-rare earth co-doped boride and nano heat insulation powder thereof
CN111793823A (en) * 2020-07-16 2020-10-20 合肥工业大学 High-purity gadolinium hexaboride polycrystal and preparation method thereof
CN111825463A (en) * 2020-06-29 2020-10-27 井冈山大学 LaB6-CrB2Composite cathode material and preparation method thereof
CN112723891A (en) * 2021-01-27 2021-04-30 合肥工业大学 Lanthanum calcium composite hexaboride polycrystalline cathode material and preparation method thereof
CN114908422A (en) * 2022-06-29 2022-08-16 合肥工业大学 Strontium-doped lanthanum hexaboride single crystal and preparation method thereof
CN114985737A (en) * 2022-05-11 2022-09-02 合肥工业大学 Multi-element hexaboride [100] monocrystal and preparation method thereof

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5918537A (en) * 1982-07-21 1984-01-30 Hitachi Ltd Thermions emission material
CN104831352A (en) * 2015-04-08 2015-08-12 井冈山大学 High-purity high-compactness (LaxSm1-x)B6 polycrystalline cathode material and preparation method thereof
CN104843727A (en) * 2015-04-08 2015-08-19 井冈山大学 Multi-component rare earth boride (LaxCe1-x)B6 solid solution polycrystalline cathode material and preparation method thereof
CN104894641A (en) * 2015-04-29 2015-09-09 井冈山大学 High-density (LaxCa1-x)B6 polycrystalline cathode material and preparation method thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5918537A (en) * 1982-07-21 1984-01-30 Hitachi Ltd Thermions emission material
CN104831352A (en) * 2015-04-08 2015-08-12 井冈山大学 High-purity high-compactness (LaxSm1-x)B6 polycrystalline cathode material and preparation method thereof
CN104843727A (en) * 2015-04-08 2015-08-19 井冈山大学 Multi-component rare earth boride (LaxCe1-x)B6 solid solution polycrystalline cathode material and preparation method thereof
CN104894641A (en) * 2015-04-29 2015-09-09 井冈山大学 High-density (LaxCa1-x)B6 polycrystalline cathode material and preparation method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
V. N. GURIN等: "Additivity of the Crystal Structure and Properties of Solid Solutions of Rare Earth Metal Hexaborides", 《TECHNICAL PHYSICS LETTERS》 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111285380A (en) * 2020-02-04 2020-06-16 天津包钢稀土研究院有限责任公司 Preparation method and application of multi-rare earth co-doped boride and nano heat insulation powder thereof
CN111825463A (en) * 2020-06-29 2020-10-27 井冈山大学 LaB6-CrB2Composite cathode material and preparation method thereof
CN111793823A (en) * 2020-07-16 2020-10-20 合肥工业大学 High-purity gadolinium hexaboride polycrystal and preparation method thereof
CN112723891A (en) * 2021-01-27 2021-04-30 合肥工业大学 Lanthanum calcium composite hexaboride polycrystalline cathode material and preparation method thereof
CN114985737A (en) * 2022-05-11 2022-09-02 合肥工业大学 Multi-element hexaboride [100] monocrystal and preparation method thereof
CN114908422A (en) * 2022-06-29 2022-08-16 合肥工业大学 Strontium-doped lanthanum hexaboride single crystal and preparation method thereof

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