Novel Cobalt-Free Oxygen-Permeable Perovskite-Type Membrane

Cobalt-free perovskite with the novel composition (Ba 0.5 Sr 0.5 )(Fe 0.8 Cu 0.2 )O 3-δ (BSFCu) was synthesized via a sol−gel method and studied with respect to the crystallographic structure as well as the oxygen ionic and the electronic conductivity. In situ X-ray diffraction (XRD) was applied to investigate the thermal dilatation and the phase stability of the BSFCu at high and intermediate temperatures. Additionally, time-dependent oxygen permeation performance measurements were carried out for BSFCu and Co-based (Ba 0.5 Sr 0.5 )(Co 0.8 Fe 0.2 )O 3-δ membranes at 1023 K for 200 h. The BSFCu phase was found to be a cubic perovskite by XRD and transmission electron microscopy. The BSFCu membrane exhibits a very high oxygen permeation and electrical conductivity as compared to known perovskite membranes. The oxygen permeation of the BSFCu membrane maintains its value for 200 h at 1023 K unlike (Ba 0.5 Sr 0.5 )(Co 0.8 Fe 0.2 )O 3-δ, whose oxygen flux was reduced by one-half during the same interval.