The oxide-ion conducting phases, La0.95Sr0.05AlO3, La0.95Sr0.05GaO3 and Y0.95Sr0.05AlO3, were synthesized by means of solid-state reaction or via a chemical route. Characterization was carried out by using X-ray diffraction, scanning electron microscopy and alternating-current impedance spectroscopy at 250 to 1000C. The low-temperature impedance results were strongly dependent upon the phase purity and microstructure, but the high-temperature conductivity data could be used to compare the conductivities of the 3 materials. Chemical modification of the Sr-doped lanthanum gallate, by replacing various cations on the A and/or B sites, decreased the conductivity, increased the activation energy and decreased the ionic conductivity. It was concluded that there was no simple correlation between the O ion conductivity and geometric factors such as the unit cell parameters and cation radii. On the other hand, cation polarizability seemed to play a very important role in improving O ion conductors which were based upon the perovskite structure.

Synthesis and Characterisation of (La,Sr)GaO3, (La,Sr)AlO3 and (Y,Sr)O3. P.S.Anderson, G.C.Mather, F.M.B.Marques, D.C.Sinclair, A.R.West: Journal of the European Ceramic Society, 1999, 19[8], 1665-73