High-performance oxygen permeation membranes: Cobalt-free Ba0.975La0.025Fe1-Cu O3- ceramics

A new group of cobalt-free perovskite oxides, Ba 0.975 La 0.025 Fe 1- x Cu x O 3- δ (BLFC, x = 0.05–0.15), was designed, characterized and applied as oxygen permeation membranes. It was found that BLFC oxides with Cu doping range of 0.075–0.15 maintain cubic perovskite phase in a wide range of temperatures. More Cu introduced at the B-site results in a gradual increase of the electrical conductivity, which is attributed to the denser overlapping of electron clouds of Cu–O bonds. With increasing Cu content, the oxygen vacancy concentration increases and the oxygen ion migration energy decreases, leading to the highest oxygen permeation flux of 1.59 mL cm −2 min −1 recorded for Ba 0.975 La 0.025 Fe 0.9 Cu 0.1 O 3- δ 1 mm thick membrane at 950 °C. However, the oxygen permeability decreases with further Cu doping, which may be correspond to a presence of defect association. Ba 0.975 La 0.025 Fe 0.9 Cu 0.10 O 3- δ membrane with 0.7 mm thickness delivers stable oxygen permeation flux of 1.57 mL cm −2 min −1 for 200 h at 900 °C. All of the obtained results indicate that the developed BLFC with optimized Cu content (i.e. x = 0.1) is a very promising material for usage in oxygen separation applications.