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

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.