Oxygen transport of A-site deficient Sr1−xFe0.5Co0.5O3−δ (x = 0–0.3) membranes

A solid-state reaction was used to prepare Sr1−x(Fe0.5Co0.5)O3−δ (x = 0–0.3) mixed (electronic and ionic)-conducting oxides. An A-site cation deficiency in Sr1−x(Fe0.5Co0.5)O3−δ (x = 0.05–0.1) causes the Sr-rich phase of grain and grain boundaries to disappear. It also enhances the stability of the perovskite structure and reduces thermal expansion at high temperatures in an Ar atmosphere. However, a further deficiency of Sr causes the segregation of a considerable amount of Co3O4 and FeO. As the Sr deficiency is increased, there is a slight decrease in the electrical conductivity in air and improvement of the oxygen permeation fluxes of slightly Sr-deficient membranes (x = 0.05, 0.1). The effect of Sr deficiency on the oxygen transport in the Sr1−x(Fe0.5Co0.5)O3−δ membrane is discussed in terms of the microstructure and phase transition.

► Sr1−x(Fe,Co)O3−δ as an oxygen transport membrane.
► Phases, microstructure, anion-transporting properties.
► Less segregated Sr-rich phases on grain boundaries.
► Sr-deficient membrane shows advantages in phase stability and thermal expansion.