High-Entropy Perovskites Pr_1−<i>x</i>Sr_<i>x</i>(Cr,Mn,Fe,Co,Ni)O_{3−<i>δ</i>} (<i>x</i> = 0–0.5): Synthesis and Oxygen Permeation Properties

Abstract

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 873 K. 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
• perovskite
• mixed ionic–electronic conducting membrane
• oxygen separation
• sol–gel synthesis