电子通过材料表面逸出真空所需之能量——逸出功是材料的一个重要特性。实际工作中往往要对材料的逸出功值提出一定的要求。例如,为了适应电真空器件功率加大、频率提高的趋势,希望热电子阴极的逸出功尽量降低;为了改进光电发射体,也必须设法使阴极表面具有低逸出功值,但同时又不能使其热发射能力过大;在热离子发电装置中却需要耐高温的、具有高 The amount of energy the electrons need to escape the vacuum through the material surface - work is an important property of the material. In actual work, it is often necessary to make certain demands on the work function of materials. For example, in order to adapt to the trend of increasing the power and frequency of electric vacuum devices, it is hoped that the work function of the thermionic cathode will be reduced as much as possible. In order to improve the photoemitter, it is also necessary to try to make the cathode surface have a low work function, So that its thermal emission capacity is too large; in the thermionic power plant but need high temperature, with high