Fe-based perovskite-type oxides as excellent oxygen-permeable and reduction-tolerant materials

Development of new mixed conductors with both high oxygen permeability and phase stability under reducing atmosphere is indispensable for realizing practical MIEC systems of oxygen separation and membrane reactor. In this study, a family of Co-free Fe-based perovskite-type oxides, (Ba,Sr)(Fe,Mn)O3−δ was prepared and their oxygen permeability and phase stability against reduction were examined. Optimum Ba doping concentration at A site was found around 30%, and Ba0.3Sr0.7FeO3−δ showed highest oxygen permeability (3.0 cm3(STP)cm− 2 min− 1 at 900 °C) in this study. Perovskite-type oxides of the Ba–Mn–Fe–O and Ba–Sr–Mn–Fe–O systems with appropriate compositions preserved the structure even after annealing in the reducing atmosphere of 5% H2/N2 at 1000 °C, showing their exceeding reduction tolerance.