Improving Balance Between Oxygen Permeability and Stability of Ba0.5Sr0.5Co0.8Fe0.2O3−δ Through High-Entropy Design

Currently, the trade-off between oxygen permeation flux and structural stability in conventional perovskite oxides restricts the practical application of oxygen permeable membranes. In this study, a high-entropy design was applied to the B-site of BSCF matrix materials, resulting in the successful synthesis of a high-entropy perovskite, Ba0.5Sr0.5Co0.71Fe0.2Ta0.03Ni0.03Zr0.03O3-δ. The crystal structure, microstructure, and elemental composition of the material were systematically characterized and analyzed. Theoretical analysis and experimental characterization confirm that the material exhibits a stable single-phase high-entropy perovskite oxide structure. Under He as the sweep gas, the membrane achieved an oxygen permeation flux of 1.28 mL·cm-2·min-1 and operated stably for over 100 h (1 mm thick, 900 °C). In a 20% CO2/He atmosphere, the flux remained above 0.92 mL·cm-2·min-1 for over 100 h, demonstrating good CO2 tolerance. Notably, when the sweep gas is returned to the pure He atmosphere, the oxygen permeation flux fully recovers to 1.28 mL·cm-2·min-1, with no evidence of leakage. These findings indicate that the proposed B-site doping strategy can break the trade-off between oxygen permeability and structural stability in conventional perovskite membranes. This advancement supports the industrialization of oxygen permeable membranes and offers valuable theoretical guidance for the design of high-performance perovskite materials.