Reactivity of the perovskite system Ca1-xSrxFeO2.5 in topotactic electrochemical oxidation at ambient temperature

Electrochemical galvanostatic oxidation of strontium-substituted CaFeO2.5 a t room temperature in an alkaline electrolyte is described. Samples with no minal composition Ca1-xSrxFeO2.5 were completely oxidized to the cubic pero vskite at x greater than or equal to 0.25. The substitution at this level i s accompanied by phase separation with formation of Ca- and Sr-enriched mic rodomains and a sharp increase in the reactivity of the matrix. The study c onfirms the phenomenological model which describes an anomalous rapid oxida tion process in perovskites for such a low temperature as a result of long- range fast oxygen transport along microdomain walls, followed by slow diffu sion over short distances in defect-free domains.