The physical mechanism of the deviation of cathode thermionic emission from the Schottky law

The deviation of the I–V characteristics of cathode materials in microwave devices from the Schottky law is caused by the occurrence of drift and diffusion of oxygen vacancies in barium-oxide crystallites, which are emission-active components of the cathode materials. The processing of experimental dependences using the proposed mathematical tools makes it possible to determine the barium–oxide–crystallite thickness and diffusivity of oxygen vacancies. The known diffusivity allows determining the presence of microimpurities in barium oxide, which affect its emission properties.