A novel Nb2O5-doped SrCo0.8Fe0.2O3−δ oxide with high permeability and stability for oxygen separation

► Nb2O5-doped SrCo0.8Fe0.2O3−δ materials were prepared as oxygen permeable membrane. ► Single perovskite structure of Nb2O5-doped SrCo0.8Fe0.2O3−δ oxides. ► Nb2O5 stabilizes the perovskite structure of SCF under low oxygen partial pressure. ► Slight dopant greatly promotes the oxygen flux at both high- and low-temperature.