Bulk Defect Chemistry of PCFC Cathode Materials: Discussion of Defect Interactions

The point defect concentrations of Ba1-xLa0xFeO3-delta perovskites, which are potential cathode materials in protonic ceramic fuel cells (PCFC), are determined by thermogravimetry. No evidence of proton-proton defect interaction is found. The O stoichiometry clearly deviates from ideal behavior, and the presence of electronic defects also modifies the hydration thermodynamics. Qualitatively, this behavior is assigned to a partial delocalization of electron holes to oxide ions adjacent to the Fe4+ ions.