To explore oxygen permeable materials, oxygen permeation properties of partially A-site substituted BaFe O3-δ perovskites were investigated. Ba sites in BaFe O3-δ were substituted with cations such as Na, Rb, Ca, Y, and La by 5%. The partial substitution with Ca, Y, and La, whose ionic radii are smaller than that of Ba, succeeded in stabilizing a cubic perovskite structure that is a highly oxygen permeable phase, as revealed by X-ray diffraction analysis. This can be explained in terms of a decrease in the tolerance factor (t). Among the Ba0.95 M 0.05 Fe O3-δ (M = Na, Rb, Ca, Y, and La) membranes tested, Ba0.95 La0.05 Fe O3-δ showed the highest oxygen permeability at 600-930°C, owing to the stabilization of the cubic phase without the formation of impurity phases. From chemical analysis, the oxygen permeability of Ba1-x Lax Fe O 3-δ membranes was correlated with the amount of oxygen defects (δ) in the lattice. The oxygen permeation flux of Ba0.95 La0.05 Fe O3-δ membrane was significantly increased by reducing its thickness. Furthermore, a Ba0.975 La0.025 Fe O3-δ membrane exhibited good phase stability under He flow at elevated temperatures. The obtained results indicate the promising properties of Ba1-x Lax Fe O3-δ membranes as a cobalt-free material that has a high oxygen permeability, good phase stability, and low cost.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry