Mixed-conducting perovskite-type Sr_xBi_1-xFeO_3-δ oxygen-permeating membranes

Sr_xBi_1-xFeO_3-δ (SBF) series mixed conductors were synthesized using standard ceramic method. The properties of such materials were characterized by XRD, O₂-TPD techniques. Abnormal crystal phenomena were found and explained and correlated with the oxygen permeation results. By analysis of the critical radius (r_c), the degree of openness of the lattice (F_v) and the average metal-oxygen bonding energy of the perovskite lattice (ABE), it was proposed that the oxygen permeation flux is determined mainly by the oxygen diffusion rate in bulk when 1-x≤0.5, and by the concentration of oxygen vacancy when 1-x≥0.5. The stability of Sr_0.5Bi_0.5FeO_3-δ was also investigated, and the high stability of it was attributed to the stable BO₆ octahedra.