Conductivity of Oxide Emitters

Abstract

Measurements of the conductivity of a BaSrCaO emitter over a range from room temperature to 1100°K indicate the existence, in well-activated cathodes, of a low temperature conduction mechanism having an activation energy of as little as 0.05 ev. Coincident with the temperature at which appreciable emission can be drawn, a high temperature conduction mechanism of 1 ev activation energy becomes evident. Application of a high pressure (25 atmospheres) of xenon to the cathode causes a marked decrease in conductivity in the high temperature range. These results are considered to confirm a hypothesis recently advanced by Loosjes and Vink that conduction in the high temperature region occurs predominantly through space currents in the pores of the oxide. The small activation energy of the low temperature conduction mechanism is considered to indicate the probability that this conduction occurs in a monolayer of barium on the surface of the oxide.