High-entropy perovskite oxides have already been studied in various fields owing to their high-entropy-induced properties. Partial substitution of an element by a lower valence element usually improves the oxygen permeability of perovskite oxides, but high substitution amounts may lead to structural instability. In this work, pure high-entropy perovskites Pr1-xSrx(Cr,Mn,Fe,Co,Ni)O3-δ with high amounts Sr up to x = 0.5 were synthesized via a sol-gel method. Several characterization methods prove that the solubility of Sr increases with higher temperatures of the heating treatment. The ceramic with x = 0.5 shows a transition from semi-conductive to metallic behavior when the temperature reaches 873K. Its oxygen flux is comparable to the low-entropy counterpart La0.6Sr0.4Co0.5Fe0.5O3-δ. A stable run of ca. 46.2 h was documented for oxygen permeation under an air/CO2 gradient.
Keywords: high-entropy oxide; mixed ionic–electronic conducting membrane; oxygen separation; perovskite; sol–gel synthesis.