Identification of the rate-determining step in oxygen transport through La(1−x)SrxFe(1−y)GayO3−δ perovskite membranes

La(1−x)SrxFe(1−y)GayO3−δ perovskites are some of the most promising materials for oxygen transport membranes due to their high oxygen semi-permeation and good chemical stability at high temperature under a wide range of oxygen partial pressures (from 0.21 to 10−19 atm.). This paper is focused on a better understanding of the influence of the Ga and Sr substitution ratios in the La(1−x)SrxFe(1−y)GayO3−δ perovskite series on oxygen semi-permeation performances, oxygen diffusion and surface exchange coefficients. This study identifies the optimal compositions of the La(1−x)SrxFe(1−y)GayO3−δ perovskite series. In addition, this study shows that the rate-determining step of oxygen transport through the membrane depends strongly on the Ga and Sr substitution ratios.