Resistance distribution in oxide coated cathodes with various nickel sleeves are measured potentiometrically with the following results.
(1) For passive sleeves, the resistance of barrier layer between (BaSr) O and Ni in reverse direction is significant at low temperatures in comparison with that of (BaSr) O, whereas at high temperatures, there is no such barrier layer. Accordingly, it seems reasonable to conclude that, at low temperatures, the conduction current through oxide coated cathode with passive sleeve is mainly determined by the resistance of the barrier layer, which is explained by the rectification theory proposed by Mott-Schottky, while, at high temperatures, the conduction is not impeded by the barrier layer, for almost all electrons emitted by granules have sufficient thermal energy to pass through the barrier.
(2) For Si active sleeves, the resistance distribution in oxide coated cathode is much involved, it needs a model more complicated than that of Mott to explain the conduction mechanism.
