Protonic conduction in Rh-doped AZrO3 (A=Ba, Sr and Ca)

The conduction behavior of rhodium-doped AZrO3 (A=Ba, Sr and Ca) was investigated using electrical and electrochemical methods at elevated temperatures. The protonic conductivity of the Rh-doped AZrO3 in hydrogen was close to that of the Y-doped AZrO3. The transport numbers of the ions in hydrogen were unity in all the samples examined in this study. Under high-oxygen partial pressures, the conductivities of the Rh-doped AZrO3 were lower than those of the Y- or In-doped AZrO3, suggesting the low conductivity of electron holes. The oxygen partial pressure dependence of the conductivity indicates that a change in the valence of the rhodium ion might suppress the generation of mobile holes under a high-oxygen partial pressure condition.