HUMIDITY SENSITIVITY OF ELECTROCHEMICAL HYDROGEN CELLS USING CALCIUM ZIRCONATE CERAMICS

The influence of humidity on the conduction of indium doped calcium zi rconate is investigated using electrochemical hydrogen concentration c ells. The resulting e.m.f. values measured in dry and humidified argon -hydrogen gas mixtures were found to be linear as a function of the lo garithm of the hydrogen gradient but with a slope of around 70% of the expected Nernst slope in the dry mixtures. The obtained curves are di scussed in terms of mixed hydrogen and oxygen conduction. In addition, electronic conduction at very low oxygen partial pressures was introd uced in order to explain all the experimental observations.