Studies on the operation mechanism of the Ba2ScAlO5 impregnated cathode

Abstract

The Ba2ScAlO5 cathode exhibits significant potential for applications in vacuum electronic devices. The tilted cathode possesses a large electron emission of 12.7 A/cm2 at 1000 °C in the DC mode. Microstructure and chemical composition characterization show that the active substance experiences chemical reactions after its activation and operation. The submicrometer-sized particle about 500 nm abundantly distributed on the cathode surface is Sc2O3, and Ba is present in a thin layer with a thickness of less than 10 nm. The simulation experiments of sintering the mixture of Ba2ScAlO5 and W with the mass ratio of 2: 3 elucidate that Ba2ScAlO5 decomposes to generate products of BaAl2O4, Ba3Sc4O9, and Sc2O3 phases. These findings enhance the understanding of the operating process of scandate cathodes and provide valuable guidance for developing more efficient cathode materials, which is significant for advancing vacuum electronic device technology.