摘要
稀土六硼化物(rare earth hexaboride,REB_(6))作为热电子发射阴极材料已经应用于各种电子发射器件中,技术的发展对REB_(6)单晶阴极材料的电子发射和力学性能提出了更高的要求.掺杂稀土元素能改善发射性能,加入过渡族金属二硼化物(transition metal boride,TMB_(2))形成共晶复合材料可以提高力学性能.采用区域熔炼法制备的掺杂REB_(6)单晶和REB_(6)与TMB_(2)定向凝固共晶复合材料都是极具应用前景的大尺寸阴极材料.首先,总结了二元REB_(6)的晶体结构和热发射性能,包括晶体取向和稀土元素对REB_(6)单晶热发射性能的影响.然后,综述了掺杂和复合REB_(6)的研究进展,重点总结了材料的性能,从实验和计算结果出发探讨了影响性能的因素.
As thermionic emission cathode material,rare earth hexaboride(REB_(6))has been used in various electron emitting devices.As technologies have developed,the requirements for the electron emission and mechanical properties of REB_(6) single crystal cathode materials have increased.Doping with rare earth elements can improve the emission properties of the material.The mechanical properties of REB_(6) single crystal can be effectively improved by adding high elastic modulus transition metal boride(TMB_(2))into REB_(6) to form the REB_(6) matrix-TMB_(2) fiber directionally solidified eutectic composite.Therefore,both doped REB_(6) single crystal and REB_(6)-TMB_(2) directionally solidified eutectic composite,which are prepared by floating zone melting,are large-size cathode materials with great application prospects.In this paper,the crystal structure of REB_(6) was presented and its influence on the properties was discussed.Then,the thermionic emission properties of binary REB_(6) single crystal were summarized,including the effects of crystal orientation and rare earth elements on the thermionic emission properties.The research progress of doped and composite of REB_(6) were reviewed,the properties of the materials were summarized,and the factors affecting the properties were discussed.
作者
刘丹敏
石峰
LIU Danmin;SHI Feng(Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China)
出处
《北京工业大学学报》
CAS
CSCD
北大核心
2022年第8期869-877,共9页
Journal of Beijing University of Technology
基金
国家自然科学基金资助项目(51972006)。
关键词
稀土六硼化物
稀土元素掺杂
定向凝固
共晶复合材料
热电子发射性能
阴极材料
rare earth hexaboride
rare earth element doping
directional solidification
eutectic composites
thermionic emission performance
cathode material