Perovskite compositions in the system La1M1Co1_8Fe8O3_, (M = Sr, Ba, Ca) exhibited high electronic and ionic conductivity. Substantial reversible weight loss was observed at elevated temperatures as the materials became increasingly oxygen deficient. Thisloss of lattice oxygen at high temperatures, which tended to increase with increasing acceptor content, resulted in a decrease in the electronic conductivity. In an oxygen partial pressure gradient, oxygen flux through dense sintered membranes of these materials was highly dependent on composition and increased with increasing temperature. The increase in oxygen flux with increasing temperature was attributed to increases in the mobility and concentration of lattice oxygen vacancies. The calculated ionic conductivities of some compositions exceeded that of yttriastabilized zirconia.

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