Defects and Ion Migration in Complex Oxides

Abstract

Ionic or mixed conductivity in complex ternary oxides has attracted considerable attention owing to both the range of applications (e.g., fuel cells, oxygen generators, oxidation catalysts) and the fundamental fascination of fast oxygen transport in solid state ionics [1, 2]. In particular, the ABO3 perovskite structure has been dubbed an “inorganic chameleon” since it displays a rich diversity of chemical compositions and properties. For instance, the mixed conductor La1-xSrxMnO3 finds use as the cathode material in solid oxide fuel cells (SOFCs) and also exhibits colossal magnetoresistance (CMR), whereas Sr/Mg doped LaGaO3 shows superior oxygen ion conductivity relative to the conventional zirconia-based electrolyte at moderate temperatures. A range of perovskite-structured ceramics, particularly cerates (ACeO3) and zirconates (AZrO3), also exhibit proton conductivity with potential fuel cell and sensor applications.