High-Entropy Perovskites Pr_1-Sr_x(Cr,Mn,Fe,Co,Ni)O_3- (x = 0-0.5): Synthesis and Oxygen Permeation Properties

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 Pr_1-Sr(Cr,Mn,Fe,Co,Ni)O_3-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 La_0.6Sr_0.4Co_0.5Fe_0.5O_3-δ. A stable run of ca. 46.2 h was documented for oxygen permeation under an air/CO₂ gradient.