Structural characterization of mixed conducting perovskites La(Ga,M)O3-δ ( M = Mn, Fe, Co, Ni)

Abstract

Comparative analysis of the structure refinement results of perovskite-like LaGa0.5M0.5O3-δ (M = Mn, Fe, Co, Ni) and data on other LaGaO3-based phases, heavily doped with transition metal cations, shows that on doping the structural changes in these oxides follow common trends for the perovskite-type systems. The maximum ionic conductivity, observed in various perovskites when the tolerance factor values are approximately 0.96-0.97, was found to correlate with the transition from orthorhombic to rhombohedral structure and maximum lattice distortion. The perovskite unit cell distortion near the orthorhombic-rhombohedral phase boundary may hence play a positive role in the ionic transport processes. © 2002 Elsevier Science Ltd. All rights reserved.