[100]、[110]、[111] CeB6单晶区熔生长与热电子发射性能研究

doi:10.15541/jim20170539

摘要/Abstract

摘要：

结合放电等离子烧结技术和光学区熔法成功制备了CeB₆单晶, 采用X射线劳埃定向系统对单晶的晶向进行分析并精密切割, 获得了[100]、[110]、[111] 取向的CeB₆单晶, 重点对[100] CeB₆单晶的结构和晶体质量进行系统表征和分析, 结果表明获得的[100] CeB₆单晶晶体质量高, 完整性好, 半高宽仅为0.24^o。热电子发射性能测试结果表明, 随着阴极温度从1773 K增加到1973 K, [100]、[110]、[111] 单晶的最大发射电流密度分别增加了2.6、3.2、1.5倍。[100] CeB₆单晶具有最好的热发射性能, 在阴极加热温度T=1973 K、外加电压4 kV时, 最大发射电流密度达到64.77 A·cm^-2, 有效逸出功为2.821 eV, 其最大发射电流密度值高于目前文献已报道水平。实验结果显示, 实验制备得到的[100] CeB₆单晶的热电子发射性能非常优异, 具有良好的应用前景。

关键词: 光学区熔法, CeB₆单晶, 热电子发射性能, [100] CeB₆单晶

Abstract:

High-quality CeB₆ single crystal was successfully prepared by optical floating zone method combining spark plasma sintering. [100], [110], [111] CeB₆ single crystals were obtained by X-ray Laue directional system equipped with precision cutting system. The structure and crystal quality of [100] CeB₆ single crystal was given emphasis to analyze and characterize. The results show that [100] CeB₆ single crystal exhibits good quality with the full width at half-maxmium (FWHM) of 0.24^o. With the increase of the cathode temperature from 1773 K to 1973 K, the maxmium emission current density of [100], [110], [111] single crystal improved by 3.6, 4.2 and 2.5 times, respectively. [100] CeB₆ single crystal possesses the best thermionic emission performance: the maxmium emission current density reaches 64.77 A·cm^-2 at 1973 K and applied voltage of 4 kV, which is larger than that of reported values in the literature up to now, and the effective work function is 2.821 eV. Therefore, [100] CeB₆ single crystal with excellent thermionic emission properties will have proming application prospects.

Key words: optical floating zone method, CeB₆ single crystal, thermionic emission properties, [100] CeB₆single crystal

中图分类号:

TQ174

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.

WANG Yan, ZHANG Jiu-Xing, YANG Xin-Yu, ZHAO Jing-Jing, NING Shu-Yu, LI Zhi. Floating Zone Growth and Thermionic Emission Property of [100], [110], [111] CeB₆ Single Crystal[J]. Journal of Inorganic Materials, 2018, 33(9): 981-986.

图/表 10

图1 熔区状态照片

Fig. 1 Photograph of molten zone state(a) Feed and seed rod began to melt; (b) Stable molten zone formed; (c) Orientated growth of CeB6 single crystal; (d) Molten zone narrowed down

图2 CeB6单晶实物照片

Fig. 2 Photograph of CeB6 single crystal

图3 单晶X射线衍射图谱

Fig. 3 Single crystal X-ray diffraction photographs==(a) Typical diffraction pattern; (b) Diffraction pattern along the <001> direction

图4 CeB6单晶劳埃衍射照片

Fig. 4 Laue diffraction patterns of CeB6 single crystal(a) Laue diffraction spots of growth plane; (b) Laue diffraction spots of [100] CeB6 single crystal; (c) Comparison diagram of [100] CeB6 single crystal with standard diffraction spots

图5 [100] CeB6单晶XRD图谱

Fig. 5 XRD pattern of [100] CeB6 single crystal

图6 [100] CeB6单晶摇摆曲线图

Fig. 6 X-ray rocking curve of [100] CeB6 single crystal

图7 [110](a)和[111](b) CeB6单晶的劳埃衍射照片

Fig. 7 Laue diffraction patterns of [110] (a) and [111] (b) CeB6 single crystal; (c) Comparison diagram of [110] single crystal; (d) Comparison diagram of [111] single crystal

图8 [100]、[110]和[111] CeB6单晶的J-U曲线图

Fig. 8 J-U curves of CeB6 single crystal(a) [100]; (b) [110]; (c) [111]

图9 [100]、[110]、[111] CeB6单晶的lgJ-U0.5曲线图

Fig. 9 lgJ-U0.5 curves of CeB6 single crystal(a) [100]; (b) [110]; (c) [111]

表1 [100]、[110]、[111] CeB6单晶不同阴极温度时的零场发射电流密度J0和有效逸出功Φeff值

Table 1 Zero emission current density J0 and effective work function Φeff of [100], [110], [111] CeB6 single crystal at different temperatures

T/K	lg J₀			J₀/(A·cm^-2)			Φ_eff/eV
T/K	[100]	[110]	[111]	[100]	[110]	[111]	[100]	[110]	[111]
1773	0.844	0.405	0.143	6.975	2.540	1.389	2.721	2.875	2.968
1873	1.216	0.671	0.419	16.455	4.683	2.626	2.754	2.956	3.050
1973	1.465	1.058	0.730	29.182	11.428	5.373	2.821	2.980	3.109

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[100]、[110]、[111] CeB₆单晶区熔生长与热电子发射性能研究

Floating Zone Growth and Thermionic Emission Property of [100], [110], [111] CeB₆ Single Crystal

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