多元稀土六硼化物由于具有优秀的热电子发射性能，在热发射和场发射阴极领域越来越受到重视，有重要的理论研究意义和应用价值。为降低工作温度、提高发射性能以满足阴极发展的新要求，迫切需要对多元稀土六硼化物热电子发射性能与结构之间的关系规律进行研究。本课题应用基于密度泛函理论的第一性原理方法计算(LaxSm1-x)B6的电子结构与功函数，研究功函数与晶体结构的关系规律。采用硼热还原和激光脉冲沉积法分别制备(LaxSm1-x)B6多晶块体和薄膜，研究其晶体结构与微观形貌对热电子发射性能的影响。将理论计算与实验事实相结合，揭示(LaxSm1-x)B6热电子发射性能－结构关系规律，找出决定性能的关键结构参数，探讨Sm掺杂对热电子发射性能的影响机制。为通过对LaB6的合理稀土掺杂实现降低阴极工作温度、提高热发射性能提供理论依据。本项目研究对探索和开发具有优异性能的新型稀土六硼化物阴极材料具有重要意义。

Owing to their excellent thermal emission properties, more attention has been paid to multiple rare-earth hexaborides in the field of thermoionic cathode and field cathode, and they demonstrate important theoretical as well as practical values. In order to reduce the operating temperature, improve the emission performance to meet the requirements of the new development of the cathodes, there is an urgent need to research the relationship between structure and thermionic emission properties. In this proposal, the electronic structure and work function for (LaxSm1-x)B6 are studied by a first-principle density functional theory calculation to get the relationship between work function and crystal structure. Polycrystalline bulks and thin films of (LaxSm1-x)B6 are prepared by using boron thermal reduction and pulsed laser deposition, respectively. We study the effects of the crystal structure and microstructure on the thermal emission properties of (LaxSm1-x)B6 via experiments. The relationships between thermal emission properties with structure of (LaxSm1-x)B6 are discussed by the combination of theoretical and experimental facts. The key structure parameters in determining the performance should be identified and the effect mechanism of Sm doping on thermal emission characteristics of (LaxSm1-x)B6 is investigated. The research provides theoretical basis for the lowering operating temperature and enhancing thermionic emitting performance by appropriate rare earth doping on the LaB6. This project is very important in the search of new rare-earth hexaborides thermal cathode materials with excellent performance.