Transport and surface properties of Sr0.25Bi0.5FeO3−δ mixed conductor

The ionic and electronic conductivities and surface properties of a perovskite-type oxide, Sr0.25Bi0.5FeO3−δ (SBF), are studied using impedance spectroscopy and gas permeation measurements. SBF is a promising cathode material for intermediate-temperature solid oxide fuel cells (SOFCs) and has a good potential to be used as a membrane material for methane conversion. The ionic conductivities and the interfacial resistances are determined from the dependence of oxygen permeation rate on membrane thickness, which are further confirmed from the dependence of oxygen permeation rate on the partial pressure of oxygen. Results suggest that the interfacial resistances limit the oxygen permeation rates in the temperature range studied (700–800 °C) at low partial pressures of oxygen.