钪型阴极表面微观发射结构的模拟计算

Numerical Simulation of Surface Microstructure of Scandate Cathodes

在阴极研究领域,钪型阴极因其大发射电流密度受到广泛关注,但其发射机制仍不明确。普遍认为表面发射层为BaxScyOz-W结构,但发射表面是动态变化的,很难确认其最佳表面发射结构。本文对钪型阴极表面BaxScyOz-W的理想发射结构进行了建模,并利用密度泛函方法对其功函数进行了计算。计算得到Ba-O-Sc-O-W表面结构的最小功函数为1.186eV。通过对计算结果的分析,讨论了不同表面原子结构对应的功函数变化。

Although the emitting mechanism is still unclear,scandate cathodes have attracted much attention owing to their high emission current density.It is generally believed that the surface emitting layer is BaxScyOz-W structure,but the emission surface is dynamic,and so it is difficult to ascertain optimal surface emission structure.In this paper,the ideal emission structure of BaxScyOz-W on the surface of scandium cathode is modeled,and the work function is calculated by density functional theory(DFT).The minimum work function of Ba-O-Sc-O-W surface structure is 1.186 eV.Based on calculation results,the change of work function corresponding to different surface atomic structure is discussed.