Oxide ion conduction in A-site deficient La-Ti-Al-O perovskite

Abstract

Oxide ion conduction in A-site deficient La-Ti-Al-O perovskites is demonstrated by complex impedance analysis and EMF measurements with an oxygen concentration cell. The oxide ion conductivity increases with decreasing the Al content. The enhancement of the conductivity has strong relation to the cation vacancy ordering and c-axis parameter expansion which were revealed by Rietveld refinement on the X-ray diffraction patterns. Dielectric relaxation which is remarkable considering the small Al content is explained by high ionic conductivity in the bulk grain and a high capacitance value in the grain boundary.