Codoping Strategy To Improve Stability and Permeability of Ba_0.6Sr_0.4FeO_3−δ-Based Perovskite Membranes

To improve the stability and oxygen permeability of Ba_0.6Sr_0.4FeO_3−δ (BSF)-based perovskite membranes, an Mg and Zr codoping strategy is proposed. The characterization by X-ray diffraction, Mössbauer spectroscopy and oxygen permeation measurements revealed that single-element Mg doping could improve the oxygen permeability of BSF-based membranes. However, in situ XRD measurements indicated that the single-element Mg doping exhibits a poor thermal stability at low oxygen partial pressure. Single-element Zr doping could improve the structure stability of BSF-based perovskites but lead to a serious decrease of oxygen permeability. Compared with the BSF-based perovskites doped by either Mg or Zr alone, Mg and Zr codoped perovskite Ba_0.6Sr_0.4Fe_0.8Mg_0.15Zr_0.05O_3−δ showed a better stability than single-element Mg doping and exhibited a higher oxygen permeability than single-element Zr doping. For the Mg and Zr codoped BSF, the oxygen permeation flux reached 0.78 mL min^–1 cm^–2 at 950 °C under an air/He oxygen partial pressure gradient.