Oxygen permeability and phase transformation of strontium-cobaltite system. Effect of B-site substitution

The relation between oxygen permeation and phase transformation of A- and B -site partially substituted strontium cobaltites, Sr0.9Ca0.1Co1-xB'O-x(2.5delta) (B' = Co, Mn, Ni, In, Fe or Al), were examined. As analyzed by high- temperature XRD, ail of these oxides transformed into perovskite-type struc ture at elevated temperatures. The transformation temperatures of the last two oxides (B' = Fe or Al) were lower than those of the others. Noticeably, the phase transformation temperatures coincided with the temperature at wh ich oxygen permeation switched on. The lowest switching-on temperature (750 degrees C) was observed with the Fe-substituted oxide among the above oxid es.