Oxygen permeability and structural features of SrFe1−xWxO3−δ membranes

The dependence of oxygen permeability of the new SrFe1−xWxO3−δ (SFW) membrane materials on temperature, oxygen partial pressure and membrane thickness was studied. The oxygen fluxes of SFW perovskite membranes was found to be controlled by the surface exchange reactions between 850 °C and 950 °C based on the dependence of oxygen permeation on the oxygen partial pressure. This result is in agreement with that from the thickness independence of the oxygen permeation flux. The deposition of Ag and a porous layer on the permeate side of the SrFe0.95W0.05O3−δ membrane leads to an increase in the oxygen fluxes by a factor of 1.8−2.3 compared with the oxygen permeability of the membrane with a non-modified surface. The stability of the oxygen fluxes across SrFe1−xWxO3−δ membranes was studied under air/He and air/CO2 gradients. The structure of membrane materials at low pO2 was studied. A specific microstructure in which oxygen vacancies are ordered inside nanosized brownmillerite-type domains was shown to be formed at х=0.05.