[100]、[110]、[111]CeB_6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] CeB_6 Single Crystal

结合放电等离子烧结技术和光学区熔法成功制备了CeB_6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CeB_6单晶,重点对[100]CeB_6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]CeB_6单晶晶体质量高,完整性好,半高宽仅为0.24o。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]CeB_6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]CeB_6单晶的热电子发射性能非常优异,具有良好的应用前景。

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.