ELECTROCHEMICAL PROPERTIES OF MIXED CONDUCTING PEROVSKITES LA(1-X)M(X)CO(1-Y)FE(Y)O(3-DELTA) (M=SR,BA,CA)

Perovskite compositions in the system La(1-x)M(x)Co(1-y)Fe(y)O(3-delta ) (M = Sr, Ba, Ca) exhibited high electronic and ionic conductivity. S ubstantial reversible weight loss was observed at elevated temperature s as the materials became increasingly oxygen deficient. This loss of lattice oxygen at high temperatures, which tended to increase with inc reasing acceptor content, resulted in a decrease in the electronic con ductivity. In an oxygen partial pressure gradient, oxygen flux through dense sintered membranes of these materials was highly dependent on c omposition 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 calcu lated ionic conductivities of some compositions exceeded that of yttri a-stabilized zirconia.