Model of dopant action in oxide cathodes

The paper describes an electrochemical model, which explains the continuous generation of Ba in oxide cathodes. In nondoped oxide cathodes electrolysis of BaO is, besides the exchange reaction from the activators in the cathode nickel, an important source of Ba during activation and life. By doping with rare earth oxides the conductivity of the oxide layer increases, which implies that the potential difference during current drawing over the oxide layer becomes lower and electrolysis of BaO is suppressed. This largely explains why doped oxide cathodes have a better life performance than nondoped cathodes. Furthermore, it is shown that the electronic conductivity of the (Ba,Sr)O layer largely controls the sensitivity for poisoning: the higher the conductivity, the larger the sensitivity for poisoning.