Effects of A-site potassium doping on oxygen permeability and intermediate-low temperature stability of Ba0.5Sr0.5Co0.8Fe0.2O3_ membranes

Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) perovskite membranes process excellent oxygen permeation flux at high temperature. However, the time-dependent flux degradation of BSCF restricts its industrial application at intermediate-low temperature. To address this issue, a series of K+ doped BSCF perovskite materials were pre-pared by EDTA-citric acid combined complexing method. The effect of K+ introduction on crystal structure, oxygen vacancy concentration, oxygen permeability and flux degradation of BSCF was systematically investi-gated. The results indicates that BSCF doped with K+ exhibits typical cubic perovskite structure and optimized oxygen permeability while the doping content of K+ is lower than 20%. Meanwhile, the oxygen permeability of BSCF can be significantly improved by introducing K+ ions, where the highest oxygen permeation flux of K0.05Ba0.45Sr0.5Co0.8Fe0.2O3-delta could reach up to 2.70 ml.min-1.cm-2. And a stable intermediate-low temperature oxygen permeation flux of 0.81 ml.min-1.cm-2 at 750 oC for 90 h can be realized for K0.1Ba0.4Sr0.5Co0.8Fe0.2O3-delta and no obvious flux degradation can be found.