La1-xNdxB6阴极材料的制备及性能研究

doi:10.15541/jim20140471

无机材料学报 ›› 2015, Vol. 30 ›› Issue (4): 363-368.DOI: 10.15541/jim20140471

La_1-_xNd_xB₆阴极材料的制备及性能研究

梁超龙¹, 张忻¹, 张久兴^{1, 2}, 张繁星¹, 王杨¹

(1．北京工业大学材料科学与工程学院, 新型功能材料教育部重点实验室, 北京100124; 2．合肥工业大学材料科学与工程学院, 合肥230009)

收稿日期:2014-09-17 修回日期:2014-12-09 出版日期:2015-04-29 网络出版日期:2015-03-26
作者简介:梁超龙(1987–), 男, 硕士研究生. E-mail: linalcl@163.com
基金资助:
国家自然科学基金(50871002);北京市自然科学基金(2112007)

Preparation and Property of La_1-_xNd_xB₆ Cathode Material

LIANG Chao-Long¹, ZHANG Xin¹, ZHANG Jiu-Xing^{1, 2}, ZHANG Fan-Xing¹, WANG Yang¹

(1. Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China; 2. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China)

Received:2014-09-17 Revised:2014-12-09 Published:2015-04-29 Online:2015-03-26
About author:LIANG Chao-Long. E-mail: linalcl@163.com
Supported by:
National Natural Science Foundation of China (50871002);Beijing Natural Science Foundation (2112007)

摘要/Abstract

摘要：

以高纯金属La块、Nd块和B粉为原料, 通过蒸发-冷凝与放电等离子烧结(SPS)结合的技术成功制备了高纯高致密的多元稀土六硼化物La_1-_xNd_xB₆块体材料。系统研究了La_1-_xNd_xB₆材料的物相组成、力学性能、电阻率及热电子发射性能。结果表明, 采用上述工艺制备了高纯高致密的La_1-_xNd_xB₆单相块体材料。烧结样品的维氏硬度和抗弯强度可达26.70 GPa和230.48 MPa。热电子发射性能测试结果表明, La_0.1Nd_0.9B₆成分块体具有最佳的热发射性能, 在1600℃, 4 kV外加电压条件下, 发射电流密度达到32.04 A/cm², 零场电流密度达到12.72 A/cm², 在同样条件下优于纯LaB₆和NdB₆块体材料的热发射性能。计算得到La_0.1Nd_0.9B₆在不同温度下的平均有效逸出功为2.72 eV, 表明适当比例的复合可以降低逸出功, 提高热电子发射性能。

关键词: 稀土六硼化物, 蒸发-冷凝, 放电等离子烧结, 热电子发射性能

Abstract:

High purity and high density La_1-_xNd_xB₆ bulks were prepared by using evaporation condensation combined spark plasma sintering (SPS) with high-purity metal La, Nd bulks and B powder as raw materials. Phase component, the mechanical properties, the resistivity and the thermionic emission properties of La_1-_xNd_xB₆ bulks were investigated systematically. The results show that high purity and high density La_1-_xNd_xB₆ single-phase bulk material can be prepared by using the above mentioned technology. The sintered samples show high value of Vickers hardness (26.70 GPa) and bending strength (230.48 MPa). According to the thermionic emission results, the bulk of La_0.1Nd_0.9B₆materials exhibits optimum thermal emission properties, the emission current density is 32.04 A/cm² and zero field current density reaches 12.72 A/cm² at the temperature of 1600℃ and the applied voltage of 4 kV, which is better than LaB₆ and NdB₆ bulk samples under the same conditions. It is shown that proper Nd content is benefit to reducing the work function and improving the thermionic emission properties, the average of effective work function for La_0.1Nd_0.9B₆ at different temperatures is 2.72 eV.

Key words: rare-earth hexaborides, evaporation-condensation, spark plasma sintering, thermionic emission property

中图分类号:

TQ174

梁超龙, 张忻, 张久兴, 张繁星, 王杨. La_1-_xNd_xB₆阴极材料的制备及性能研究[J]. 无机材料学报, 2015, 30(4): 363-368.

LIANG Chao-Long, ZHANG Xin, ZHANG Jiu-Xing, ZHANG Fan-Xing, WANG Yang. Preparation and Property of La_1-_xNd_xB₆ Cathode Material[J]. Journal of Inorganic Materials, 2015, 30(4): 363-368.

图/表 8

图1 粉末的TEM和SEM照片

Fig. 1 TEM and SEM images of powders TEM images of LaH2 (a) and NdH2 (b) nanopowders; SEM image of B powders (c)

图2 1500℃原位反应烧结La1-xNdxB6块体的XRD图谱

Fig. 2 XRD patterns of La1-xNdxB6 polycrystalline prepared by in situ reaction

表1 La1-xNdxB6烧结块体的相对密度和晶格常数

Table 1 Relative density and lattice constant of La1-xNdxB6 polycrystalline

Sample	Lattice constant /nm	Theory density /(g·cm^-3)	Actual density /(g·cm^-3)	Relative density/%
LaB₆	0.4151	4.712	4.534	96.2
La_0.9Nd_0.1B₆	0.4144	4.734	4.545	96.0
La_0.7Nd_0.3B₆	0.4135	4.782	4.564	95.4
La_0.5Nd_0.5B₆	0.4122	4.830	4.665	96.6
La_0.3Nd_0.7B₆	0.4123	4.878	4.575	93.8
La_0.1Nd_0.9B₆	0.4121	4.926	4.635	94.1
NdB₆	0.4120	4.936	4.752	96.3

图3 La1-xNdxB6断口扫描电镜照片

Fig. 3 Fracture SEM images of La1-xNdxB6 polycrystalline (a) x=0.1; (b) x=0.3; (c) x=0.5; (d) x=0.7; (e) x=0.9

图4 La1-xNdxB6块体维氏硬度和抗弯强度随Nd含量变化曲线

Fig. 4 Vickers hardness and bending strength curves of La1-xNdxB6 as a function of Nd content

图5 La1-xNdxB6块体电阻率与测试温度关系曲线

Fig. 5 Electrical resistivity curves of La1-xNdxB6 as a function of testing temperature

表2 不同温度下La1-xNdxB6块体的有效逸出功

Table 2 Effective work function of La1-xNdxB6 at different testing temperatures

Nd content , x	j₀/ (A?cm^-2)			Average work function /eV
Nd content , x	1400℃	1500℃	1600℃	Average work function /eV
x=0	-	5.10	12.42	2.78
x=0.1	-	-	2.29	3.07
x=0.3	-	1.11	4.36	2.93
x=0.5	-	11.02	19.13	2.70
x=0.7	-	2.50	4.01	2.93
x=0.9	2.29	10.12	12.72	2.72
x=1.0	4.42	7.54	9.25	2.72

图6 肖特基直线外延法计算La1-xNdxB6块体零场电流密度

Fig. 6 Calculate J0 of La1-xNdxB6 polycrystalline by method of Schottky line (a) x=0.1; (b) x=0.3; (c) x=0.5; (d) x=0.7; (e) x=0.9; (f) x=0; (g) x=1.0

参考文献 13

[1]	TANAKA T, NISHITANI R, OSHIMA C, et al.The preparation and properties of CeB6, SmB6, and GdB6.J. Appl. Phys., 1980, 51(7): 3877-3880.
[2]	CHEN CHUN-HUA, AIZAWA T, IYI N, et al.Structural refinement and thermal expansion of hexaborides.Journal of Alloys and Compounds, 2004, 366(1/2): L6-L8.
[3]	LATE D J, SINGH V R, SINHA S, et al.Synthesis of LaB6 micro/nano structures using picoseconds (Nd: YAG) laser and its field emission investigations. Appl. Phys. A, 2009, 97(4): 905-909.
[4]	ZHOU SHEN-LIN, LIU DAN-MIN, ZHANG JIU-XING.Fabrication and characterization of high-purity nanostructured bulk LaB6 polycrystal cathode material.Journal of Inorganic Materials, 2008, 23(6): 1199-1204.
[5]	ZHOU SHEN-LIN, ZHANG JIU-XING, LIU DAN-MIN, et al.Properties of CeB6 cathode fabricated by spark plasma reactive liquid Phase Sintering Method.Journal of Inorganic Materials, 2009, 24(4): 793-797.
[6]	SCHMIDT P H, JOY D C.Low work function electron emitter hexaborides. J. Vac. Sci. Technol., 1978, 15(6): 1809-1810.
[7]	BAO LI-HONG, TEGUS O, ZHANG JIU-XING, et al.Large emission current density of LaxCe1-xB6 high quality single crystals grown by floating zone technique.Journal of Alloys and Compounds, 2013, 558(13): 39-43.
[8]	HUANG MEI-SONG, CHEN YUN-ZHI, ZHANG YAO-BIN, et al. Preparation of high-density LaB6 polycrystal.Rare Metals andCemented Carbides, 2012, 40(3): 33-38.
[9]	CHENG WEI, HUANG MEI-SONG, YANG LU-HUI, et al.Preparation of high-density LaB6 polycrystalline by low-pressure solid-state sintering.Mining AND Metallurgical Engineering, 2014, 34(2): 122-124.
[10]	MA RU-GUANG, LIU DAN-MIN, ZHOU SHEN-LIN, et al.Fabrication and emission property of polycrystalline La0.4Pr0.6B6 bulk prepared by spark plasma sintering.Journal of Inorganic Materials, 2010, 25(7): 743-747.
[11]	BAO LI-HONG, ZHANG JIU-XING, ZHOU SHEN-LIN.Effect of Ba-doping on the structural, grain orientation and thermionic emission properties of hexaboride GdB6.Journal of Inorganic Materials, 2011, 26(10): 1116-1120.
[12]	CHEN CH, XUAN Y, OTANI S, et al.Temperature and loading time dependence of hardness of LaB6, YB6 and TiC single crystals.Journal of Alloys and Compounds, 2003, 350(1/2): L4-L6.
[13]	ZHOU SHEN-LIN, ZHANG JIU-XING, LIU DAN-MIN.Properties of high density LaB6 cathode prepared by spark plasma solid phase sintering.High Power Laser and Particle Beams, 2010, 22(1): 171-175.

[1]	万朋, 李勉, 黄庆. 熔盐辅助合成Dy₃Si₂C₂包裹SiC粉体及其陶瓷的烧结行为[J]. 无机材料学报, 2021, 36(1): 49-54.
[2]	赵占奎, 李涛, 鲁书含, 王明罡, 张京京, 程道文, 吴臣, 迟悦, 王虹力. SPS界面反应增强机制调控的软磁复合材料磁性能和电阻率[J]. 无机材料学报, 2020, 35(11): 1223-1226.
[3]	王伟, 罗世阶, 鲜聪, 肖群, 杨洋, 欧云, 刘运牙, 谢淑红. 水热合成BiCl₃/Bi₂S₃复合材料的热电性能[J]. 无机材料学报, 2019, 34(3): 328-334.
[4]	王衍, 张久兴, 杨新宇, 赵晶晶, 宁舒羽, 李志. [100]、[110]、[111] CeB₆单晶区熔生长与热电子发射性能研究[J]. 无机材料学报, 2018, 33(9): 981-986.
[5]	王明辉, 钟洪彬, 范宇驰, 陈婷. SPS烧结制备生物活性镁黄长石陶瓷[J]. 无机材料学报, 2017, 32(8): 825-830.
[6]	安丽琼, 章健, 范润华, GOTO Takashi, 王士维. Nd³⁺:Lu₂O₃放电等离子烧结及光学性能[J]. 无机材料学报, 2017, 32(12): 1315-1320.
[7]	李松浩, 张忻, 刘洪亮, 郑亮, 张久兴. Ag掺杂SnSe化合物的制备及热电性能[J]. 无机材料学报, 2016, 31(7): 751-755.
[8]	姚铮, 仇鹏飞, 李小亚, 陈立东. n型填充方钴矿热电材料的快速制备研究[J]. 无机材料学报, 2016, 31(12): 1375-1382.
[9]	邢志波, 李敬锋. AgSn₁₈SbTe₂₀无铅中温热电材料的粉末冶金法制备工艺及其对性能的影响[J]. 无机材料学报, 2015, 30(8): 872-876.
[10]	唐云山, 柏胜强,任都迪,廖锦城,张澜庭, 陈立东. Yb_0.3Co₄Sb₁₂/Mo-Cu热电元件的界面结构与界面电阻[J]. 无机材料学报, 2015, 30(3): 256-260.
[11]	黄林芸, 李晨辉, 柯文明, 史玉升, 贺智勇, 张启富. 稀土氧化物对SPS烧结AlN陶瓷电性能的影响[J]. 无机材料学报, 2015, 30(3): 267-271.
[12]	张繁星, 张忻, 张久兴, 梁超龙, 黄颖凯. 悬浮区域熔炼法制备Ce_1-_xPr_xB₆单晶体及其热发射性能研究[J]. 无机材料学报, 2014, 29(10): 1073-1076.
[13]	韩志明, 张忻, 路清梅, 张久兴, 张飞鹏. (Mg₂Si_1-xSb_x)_0.4-(Mg₂Sn)_0.6固溶体合金的制备及热电输运特性[J]. 无机材料学报, 2012, 27(8): 822-826.
[14]	林挺, 许志斌, 邓莲芸, 任玉英, 施鹰, 谢建军. Ce:Lu₂SiO₅闪烁陶瓷的放电等离子烧结与发光性能[J]. 无机材料学报, 2011, 26(11): 1210-1214.
[15]	包黎红, 张久兴, 周身林. Ba掺杂对稀土硼化物GdB₆结构, 晶粒取向和热发射性能的影响[J]. 无机材料学报, 2011, 26(10): 1116-1120.

La_1-_xNd_xB₆阴极材料的制备及性能研究

Preparation and Property of La_1-_xNd_xB₆ Cathode Material

RichHTML

PDF (PC)

可视化

被引次数

摘要/Abstract

引用本文

使用本文

图/表 8

参考文献 13

相关文章 15

编辑推荐

Metrics

本文评价