LaB₆単結晶の表面と熱電子放射

抄録

LaB₆ is one of the fascinating cathode materials I to obtain the electron beam with high brightness. In this article, brief reviews are given on the recent development in the study of the surfaces of LaB₆ single crystal. Thermionic emission properties are discussed based on the electronic structure of bulk. and its surface structure. The values of work function of borides are much correlated with its electron density as similar to the case of metalic element and is explained in view of the theory proposed by Lang and Kohn. The change of surfaces due to ion bombardment and oxygen chemisorption are also discussed and it is pointed out that the three dimentional frame work of boron at LaB6 surface is important for stabilities of the surface and the configuration of La atoms at the surface for the emission properties and anisotropy of work function.