CN102808215A

CN102808215A - Preparation method of large-dimension multi-element rare earth boride (Ce0.9Pr0.1)B6 single crystal

Info

Publication number: CN102808215A
Application number: CN2012102227114A
Authority: CN
Inventors: 张久兴; 李晓娜; 张忻; 包黎红; 张宁; 张繁星
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2012-06-28
Filing date: 2012-06-28
Publication date: 2012-12-05

Abstract

The invention discloses a preparation method of a multi-element rare earth boride (Ce0.9Pr0.1)B6 single crystal, and belongs to the technical field of rare earth boride hot cathode materials. At present, the research about the multi-element rare earth boride single crystal is little; further, the prepared single crystal is small in dimension and low in purity; and the requirement of actual application cannot be met. By using the preparation method, the high-quality and large-dimension multi-element rare earth boride (Ce0.9Pr0.1)B6 single crystal is prepared by adopting a method for combining discharge plasma sintering with floating zone melting. The (Ce0.9Pr0.1)B6 single crystal prepared by using CeB6 and PrB6 powder as raw materials is a phi4.5 mm*40 mm cylinder, and the test result of a single-crystal diffractometer shows that the single crystal is favorable in quality and a twin crystal phenomenon does not occur.

Description

Large size multicomponent rare earth boride (Ce 0.9Pr 0.1) B 6The single crystal preparation method

Technical field

The invention belongs to rare-earth boride hot cathode material technical field, be specifically related to utilize optical region smelting method for preparing high quality, large size multicomponent rare earth boride (Ce _0.9Pr _0.1) B ₆Single crystal.

Background technology

Rare-earth hexboride compound (ReB ₆, Re is a REE) and be one type of boride with special crystal structure, characteristics such as have the fusing point height, hardness is big, work function is low, emission is big, good, the anti-ion bombardment ability of chemicalstability is strong are the ideal hot cathode materials.After finding that lanthanum hexaborane has excellent electron emission characteristic the sixties in 20th century, opened the rare-earth boride research boom.Owing to there is very strong ys between the rare-earth boride powder, the conventional sintering method is difficult to prepare high fine and close polycrystalline bulk, has directly influenced the emitting performance of material, is difficult to reach application request.Afterwards; The research direction of hexaboride has turned to the preparation and the application of monocrystalline; Adopt vapour deposition process and laser deposition to prepare one-dimensional nano line and two-dimensional film material, but, influence speed of response and reaction product because vapour deposition process reactant in reaction process is easy to suction.Thin-film material exists and the problem of substrate adhesion difference can't obtain high current density.Can adopt the al solvent legal system to be equipped with the single crystal of hexaboride, this method has the introducing of impurity to be difficult to prepare high-quality monocrystalline in crystal growing process, and crystalline size is less, has only 1 * 1 * 2 mm ³

Summary of the invention

The objective of the invention is to solve prior art problems, and a kind of high quality, large scale rare-earth boride (Ce are provided _0.9Pr _0.1) B ₆The preparation method of single crystal.

The method that the present invention adopts discharge plasma sintering (SPS) to combine with floating zone melting prepares large size, high quality (Ce _0.9Pr _0.1) B ₆Single crystal, concrete steps are following:

1) with CeB ₆Powder, PrB ₆Powder is packed into after the 9:1 milling mixing in the graphite jig in molar ratio.Mould is placed the SPS sintering cavity, be lower than sintering under the vacuum condition of 5Pa at total gas pressure.Temperature rise rate with 80～100 ℃/min is warming up to 1100～1150 ℃, and insulation 3-5min cools to room temperature with the furnace, obtains (Ce _0.9Pr _0.1) B ₆Polycrystalline rod;

2) adopting the optical region smelting furnace, is (the Ce of 6～8mm with diameter _0.9Pr _0.1) B ₆Polycrystalline rod melts for young brilliant and charge bar carry out first time district.After equipment is evacuated to below the 1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 1.5 ~ 2L/min, and 30min zone melting furnace power is increased to young crystalline substance and charge bar fusing and forms stablizes the melting zone; In order to make the melting zone more even; With seed crystal and charge bar reverse rotation, rotating speed is 30rpm, the 15 ~ 20mm/h of crystalline growth velocity unit;

2) adopt the optical region smelting furnace, once to distinguish molten (Ce _0.9Pr _0.1) B ₆Be charge bar, with SPS agglomerating (Ce _0.9Pr _0.1) B ₆It is molten that polycrystalline rod is that young crystalline substance carries out second time district.After equipment is evacuated to below the 1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 1.5 ~ 2L/min, and 30min zone melting furnace power is increased to young crystalline substance and charge bar fusing and forms stablizes the melting zone; In order to make the melting zone more even; With seed crystal and charge bar reverse rotation, rotating speed is 30rpm, the 8 ~ 10mm/h of crystalline growth velocity unit;

Further, the described CeB of step 1) ₆, PrB ₆The purity of powder is respectively 99.8% and 96.7%, and granularity is all less than 360 orders.

Compared with prior art, the present invention has following beneficial effect:

Multicomponent rare earth boride (the Ce that the present invention is prepared _0.9Pr _0.1) B ₆The single crystal growth size is big, quality is high, and single crystal is the columnar block of φ 4.5mm * 40mm, and 360 degree Phi scanning single crystal diffractometer test results show that each diffraction spot is independently spot, have good symmetry, explain that this single crystal quality is good.

Description of drawings

(the Ce of Fig. 1, embodiment 1 preparation _0..9Pr _0..1) B ₆The photo of single crystal

(the Ce of Fig. 2, embodiment 1 preparation _0.9Pr _0.1) B ₆The single crystal diffractometer 360 degree rapid scanning photos of monocrystalline

(the Ce of Fig. 3, embodiment 1 preparation _0.9Pr _0.1) B ₆Monocrystalline is along the single crystal diffractometer 360 degree low Loran PRR photos of (001) direction

(the Ce of Fig. 4, embodiment 2 preparations _0.9Pr _0.1) B ₆Monocrystalline is along the single crystal diffractometer 360 degree low Loran PRR photos of (001) direction

Below in conjunction with accompanying drawing and embodiment the present invention is described further, but protection scope of the present invention is not limited to following embodiment.

Embodiment

The discharging plasma sintering equipment model is SPS-3.20MK-V; Described optical region smelting furnace model is FZ-T-12000-S-BU-PC.

Embodiment 1

1) with CeB ₆Powder, PrB ₆Powder is packed into after by atomic ratio 9:1 milling mixing in the graphite jig.Mould is placed the SPS sintering cavity, be evacuated to total gas pressure to 5Pa, be warming up to 1150 ℃ with the temperature rise rate of 100 ℃/min, insulation 5min cools to room temperature with the furnace, obtains (Ce _0.9Pr _0.1) B ₆Polycrystalline rod;

2) adopting the optical region smelting furnace, is (the Ce of 8mm with the diameter _0.9Pr _0.1) B ₆Polycrystalline rod melts for young brilliant and charge bar carry out first time district.After equipment is evacuated to below the 1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 2L/min, and 30min zone melting furnace power is increased to young brilliant and charge bar and all melts and form and stablize the melting zone; The crystal growing process medium speed is 30rpm, the 15mm/h of crystalline growth velocity unit;

3) adopt the optical region smelting furnace, with (Ce after once melt in the district _0.9Pr _0.1) B ₆Be charge bar, it is molten to be with SPS agglomerating polycrystalline rod that young crystalline substance carries out the secondary district.After equipment is evacuated to 0.1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 2L/min, and 30min zone melting furnace power is increased to young brilliant and charge bar and all melts and form and stablize the melting zone; The charge bar rotating speed is 30rpm in the crystal growing process, the 8mm/h of crystalline growth velocity unit;

Embodiment 2

1) with CeB ₆Powder, PrB ₆Powder is packed into after by atomic ratio 9:1 milling mixing in the graphite jig.Mould is placed the SPS sintering cavity, be evacuated to total gas pressure to 5Pa, be warming up to 1100 ℃ with the temperature rise rate of 80 ℃/min, insulation 3min cools to room temperature with the furnace, obtains (Ce _0.9Pr _0.1) B ₆Polycrystalline rod;

2) adopting the optical region smelting furnace, is (the Ce of 6mm with the diameter _0.9Pr _0.1) B ₆Polycrystalline rod melts for young brilliant and charge bar carry out first time district.After equipment is evacuated to below the 1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 1.5L/min, and 30min zone melting furnace power is increased to young brilliant and charge bar and all melts and form and stablize the melting zone; The crystal growing process medium speed is 30rpm, the 20mm/h of crystalline growth velocity unit;

3) adopt the optical region smelting furnace, with (Ce after once melt in the district _0.9Pr _0.1) B ₆Be charge bar, it is molten to be with SPS agglomerating polycrystalline rod that young crystalline substance carries out the secondary district.After equipment is evacuated to 0.1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 1.5L/min, and 30min zone melting furnace power is increased to young crystalline substance and charge bar fusing and forms stablizes the melting zone; The charge bar rotating speed is 30rpm in the crystal growing process, the 10mm/h of crystalline growth velocity unit;

(the Ce for preparing among the embodiment _0.9Pr _0.1) B ₆Single crystal is bluish voilet, and is as shown in Figure 1, the sample even thickness, and smooth surface is not found the vestige that gas and impurity overflow.Fig. 2 is embodiment 1 preparation (Ce _0.9Pr _0.1) B ₆The single crystal diffractometer 360 degree rapid scanning photos of single crystal, diffraction spot is separate, and symmetry is good, the polycrystalline ring do not occur, but preliminary judgement is a monocrystalline.Fig. 3 is the (Ce of embodiment 1 preparation _0.9Pr _0.1) B ₆The single crystal diffractometer 360 degree low Loran PRR photos of single crystal, diffraction spot is complete, and phenomenon interpret sample such as splitting hangover not occurring is that monocrystalline and quality are good.Fig. 4 is the (Ce of embodiment 2 preparations _0.9Pr _0.1) B ₆The single crystal diffractometer 360 degree low Loran PRR photos of single crystal still can be prepared high-quality single crystal after diffraction spot can be found out the growth parameter(s) change.

Claims

1. multicomponent rare earth boride (Ce _0.9Pr _0.1) B ₆The preparation method of single crystal is characterized in that, may further comprise the steps:

1) with CeB ₆Powder, PrB ₆Powder is packed into after the 9:1 milling mixing in the graphite jig in molar ratio; Mould is placed the SPS sintering cavity, be lower than sintering under the vacuum condition of 5Pa at total gas pressure; Temperature rise rate with 80 ~ 100 ℃/min is warming up to 1100 ~ 1150 ℃, and insulation 3-5min cools to room temperature with the furnace, obtains (Ce _0.9Pr _0.1) B ₆Polycrystalline rod;

2) adopting the optical region smelting furnace, is the agglomerating (Ce of 6～8mm with diameter _0.9Pr _0.1) B ₆Polycrystalline rod is that young crystalline substance and charge bar are once distinguished molten; After equipment is evacuated to below the 1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 1.5 ~ 2L/min, and 30min zone melting furnace power is increased to charge bar and young brilliant fusing and forms stablizes the melting zone; The charge bar rotating speed is 30rpm in the crystal growing process, the 15 ~ 20mm/h of crystalline growth velocity unit;

3) adopt the optical region smelting furnace, with (Ce after once melt in the district _0.9Pr _0.1) B ₆Be charge bar, with SPS agglomerating (Ce _0.9Pr _0.1) B ₆It is molten that polycrystalline rod is that young crystalline substance carries out the secondary district; After equipment is evacuated to 0.1Pa; Pour argon gas to the air pressure that flows and rise to 0.5MPa, gas flow rate is 1.5 ~ 2L/min, and 30min zone melting furnace power is increased to charge bar and young brilliant fusing; The charge bar rotating speed is 30rpm in the crystal growing process, the 8 ~ 10mm/h of crystalline growth velocity unit.

2. method according to claim 1 is characterized in that, described CeB ₆The purity of powder is 99.8%, and granularity is less than 360 orders.

3. method according to claim 1 is characterized in that, described PrB ₆The purity of powder is 96.7%, and granularity is less than 360 orders.