Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material

A rare earth boride, single crystal material technology, applied in the growth of polycrystalline materials, chemical instruments and methods, single crystal growth and other directions, can solve the problems of small size and poor quality, and achieve large size, high quality and high purity. Effect

Inactive Publication Date: 2012-05-02
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the existing sample size is small, poor quality (sub-grain boundaries exist in the crysta

Method used

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  • Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material
  • Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material
  • Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0014] Example 1

[0015] (1) LaB 6 With CeB 6 After the powder is mechanically mixed in a chemical ratio of 6:4, it is put into a graphite mold with an inner diameter of Ф15mm and a height of 140mm for vacuum discharge plasma sintering (SPS). The sintering parameters are as follows, sintering temperature: 1150°C, sintering pressure: 0MPa, holding time: 5min, heating rate: 110°C / min.

[0016] (2) Cut the sintered polycrystalline rod into seed crystals and material rods with a diameter of Φ7mm, and perform zone melting in an optical zone melting furnace. In order to effectively suppress the volatilization and oxidation of La and Ce elements, high-purity flowing argon gas is passed into the quartz tube, the gas flow rate is 1L / min, and the gas pressure is 0.5MPa. In order to make the melting zone more uniform, the seed crystal and the material rod are rotated in opposite directions, the speed is 30rpm, and the growth speed is 7mm / h.

[0017] From figure 1 It can be seen that La 0.6 C...

Example Embodiment

[0018] Example 2

[0019] (1) LaB 6 With CeB 6 After the powder is mechanically mixed in a chemical ratio of 4:6, it is put into a graphite mold with an inner diameter of 15mm and a height of 140mm for vacuum discharge plasma sintering (SPS). The sintering parameters are as follows, sintering temperature: 1200°C, sintering pressure: 10MPa, holding time: 5min, heating rate: 110°C / min.

[0020] (2) Cut the sintered polycrystalline rod into seed crystals and material rods with a diameter of Φ7mm, and perform zone melting in an optical zone melting furnace. In order to effectively suppress the volatilization and oxidation of La and Ce elements, high-purity flowing argon gas is passed into the quartz tube, the gas flow rate is 2L / min, and the gas pressure is 0.6MPa. In order to make the melting zone more uniform, the seed crystal and the material rod are rotated in opposite directions at a speed of 40 rpm and a growth rate of 8 mm / h.

[0021] 360-degree Phi scan fast scan and slow scan ...

Example Embodiment

[0022] Example 3

[0023] (1) Put the LaB6 and CeB6 powders into a graphite mold with an inner diameter of Ф15mm and a height of 140mm at a chemical ratio of 2:8 for vacuum spark plasma sintering (SPS). The sintering parameters are as follows, sintering temperature: 1200°C, sintering pressure: 20MPa, holding time: 5min, heating rate: 120°C / min.

[0024] (2) Cut the sintered polycrystalline rod into seed crystals and material rods with a diameter of Φ7mm, and perform zone melting in an optical zone melting furnace. In order to effectively inhibit the volatilization and oxidation of La and Ce elements, high-purity flowing argon gas was passed into the quartz tube, the gas flow rate was 2L / min, and the gas pressure was 0.7MPa. In order to make the melting zone more uniform, the seed crystal and the material rod are rotated in opposite directions at a speed of 40 rpm and a growth rate of 10 mm / h.

[0025] 360-degree Phi scan fast scan and slow scan along the (001) direction results sho...

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Abstract

The invention discloses a preparation method of a multicomponent large-size rare earth boride La*Ce1-xB6 monocrystalline block cathode material, belonging to the technical field of rare earth boride thermionic cathode and cold cathode materials. At present, little research has been done into multicomponent rare earth boride monocrystals, the preparation technology in the prior art is complicated, and the prepared monocrystals in the prior art has bad quality and small size and is difficult for practical application. The cathode material disclosed herein is represented as LaxCe1-xB6, wherein, x ranges from 0.2-0.6. The method disclosed herein is characterized in that: a discharge plasma sintering method is adopted, a LaxCe1-xB6 polycrystalline rod is prepared in a high vacuum environment, and then the prepared polycrystalline rod is smelted in a smelting furnace of an optic zone. In the process of crystal growth, for effectively inhibiting the volatilization and oxidation of La and Ce, high-purity flow argon is introduced to a quartz tube, wherein, the gas flow velocity is 1-2 L/min, and the gas pressure is 0.5-0.7 MPa. For making a melting zone more uniform, a seed crystal and a charge bar are reversely rotated, wherein, the rotating speed is 30-40 rpm, and the growth speed is 7-10 mm/h. The prepared monocrystal has the advantages of large size, high purity, and good quality.

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 La x Ce 1-x B 6 (0.2≤x≤0.6) method for single crystal bulk 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. Research hotspots mainly focus on LaB 6 and CeB 6 and other binary rare earth boride cathodes. In the late 1960s, it was discovered that certain polynary rare earth borides such as (La-Eu)B 6 It has more excellent emission properties than binary rare earth borides. But so far, the research and application of polynary rare earth borides at home and abroad are very scarce, especially the research on single crystals. [0003] At present, the aluminum solvent method is usually used to prepare rare earth boride single crystal blocks,...

Claims

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Application Information

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IPC IPC(8): C30B29/10C30B13/28
Inventor 张久兴包黎红张宁
Owner BEIJING UNIV OF TECH
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