Effect of B-site tungsten doping on structure and oxygen permeation properties of SrCo0.8Fe0.2O3−δ perovskite membranes

The effects of partial substitution of cobalt in SrCo0.8Fe0.2O3−δ (SCF) by W6+ cations on the crystal structure, microstructure and oxygen flux of the new membrane materials are systematically investigated using XRD, HREM and oxygen permeation studies. Doping of SCF by tungsten (x ≥ 0.03) results in the endotaxial growth of nanosized Sr2CoWO6 domains distributed in the matrix of nonstoichiometric perovskite. The obtained dependencies of oxygen fluxes across SCFW membranes on temperature (650 ≤ T ≤ 950 °C), oxygen partial pressure, thickness (1.65 ≤ L ≤ 2.55 mm) and surface modification indicate that oxygen permeation process is controlled by both surface exchange reactions and bulk oxygen diffusion. Tungsten-substituted SCF membrane materials possess an improved performance in the presence of carbon dioxide.