Physical foundations of the oxide cathodes

Abstract A novel explanation of the low values of work function in case of activated (partly deoxidized) polycrystalline oxides of alkali and alkaline earth metals is offered. Use of the metallic plasma model to the conducting oxides leads to the following values (in eV): 1.00, 1.67, 1.50, 1.44, 1.46 and 1.59 for activated Cs2O, CaO, SrO, BaO, Y2O3 and La2O3, respectively. The main reason of low work function of the oxide cathodes is very low density of free electrons in the emitting surface layer.