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Method for preparing large rare-earth boride SmB<6> single crystal

A rare earth boride and single crystal technology, applied in the field of preparing SmB6 single crystal materials, can solve the problems of small single crystal size, lower single crystal purity, lower emission current density, etc., and achieve the effect of large growth size and high quality

Inactive Publication Date: 2013-07-17
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] At present, the rare earth boride SmB is usually prepared by the aluminum solvent method. 6 Single crystal, but the size of the single crystal prepared by this method is small, and it is easy to bring impurity aluminum elements in the preparation process, which reduces the purity of the single crystal, reduces the emission current density, and limits its practical application

Method used

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  • Method for preparing large rare-earth boride SmB&lt;6&gt; single crystal
  • Method for preparing large rare-earth boride SmB&lt;6&gt; single crystal
  • Method for preparing large rare-earth boride SmB&lt;6&gt; single crystal

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] 1) Mix Sm powder and B powder by ball milling at a molar ratio of 1:6 and put them into graphite molds. The mold is placed in the SPS sintering cavity, and sintered under the vacuum condition with the total air pressure lower than 5Pa. Raise the temperature to 1450 °C at a heating rate of 100 °C / min, keep it for 5 min, and cool to room temperature with the furnace to obtain SmB 6 polycrystalline rod;

[0020] 2) Using an optical zone melting furnace, the SmB with a diameter of 6mm 6 The polycrystalline rod is the first zone melting for the seed crystal and material rod. After the equipment is evacuated to below 1Pa, flow argon gas into it until the pressure rises to 0.5MPa, the gas flow rate is 1.5L / min, and the power of the furnace in the 30min zone is increased to melt the seed crystal and the rod and form a stable melting zone. In order to make the melting zone More uniformly, the seed crystal and the material rod are rotated in reverse, the rotation speed is 30rp...

Embodiment 2

[0024] 1) Mix Sm powder and B powder by ball milling at a molar ratio of 1:6 and put them into graphite molds. The mold is placed in the SPS sintering cavity, and sintered under the vacuum condition with the total air pressure lower than 5Pa. Raise the temperature to 1500°C at a heating rate of 110°C / min, hold for 8 minutes, and cool to room temperature with the furnace to obtain SmB 6 polycrystalline rod;

[0025] 2) Using an optical zone melting furnace, the SmB with a diameter of 8mm 6 The polycrystalline rod is the first zone melting for the seed crystal and material rod. After the equipment is evacuated to below 1Pa, flow argon gas into it until the pressure rises to 0.5MPa, the gas flow rate is 2L / min, and the power of the furnace in the 30min zone is increased to melt the seed crystal and material rod and form a stable melting zone. In order to make the melting zone more Evenly, reversely rotate the seed crystal and material rod, the rotation speed is 30rpm, and the ...

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Abstract

The invention discloses a method for preparing a large rare-earth boride SmB<6> single crystal, and belongs to the technical field of rare-earth boride hot cathode materials. At present, preparation and research for rare-earth boride SmB<6> single crystals are rare, a process for preparing the rare-earth boride SmB<6> single crystals is complicated, and the single crystals are poor in quality and difficult in actual application, and are small. The method has the advantages that spark plasma sintering and floating zone melting are combined with each other, and the high-quality large rare-earth boride SmB<6> single crystal is prepared in a high-vacuum environment; the SmB<6> single crystal prepared from Sm powder and B powder which are original raw materials is a cylinder, and as shown by results of tests implemented by a single-crystal diffractometer, the single crystal is good in quality and free of crystal twinning.

Description

technical field [0001] The invention belongs to the technical field of rare earth boride cathode materials, and in particular relates to a method for preparing SmB by using an optical zone smelting method. 6 Methods for single crystal materials. technical background [0002] Since 1951, J.M.Lafferty of the United States discovered that lanthanum hexaboride has excellent electron emission characteristics, which started the research boom of rare earth borides. Rare earth hexaboride (ReB 6 , Re is a rare earth element) is a class of borides with a special crystal structure, which has the characteristics of high melting point, high hardness, low work function, high emission current density, good chemical stability, and strong ion bombardment resistance. hot cathode material. The research hotspots of rare earth hexaborides mainly focus on LaB 6 and CeB 6 and other binary rare earth boride cathodes. Sm element is widely used as an important rare earth element, and SmB 6 The...

Claims

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Application Information

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IPC IPC(8): C30B13/00C30B29/10
Inventor 张忻张繁星李晓娜张久兴
Owner BEIJING UNIV OF TECH
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