Sn-containing SrCo0.8Fe0.2O3-δ O-permeable dense ceramic membranes were prepared and characterized. The solid solubility of Sn in SrCo0.8Fe0.2O3-δ was found not higher than 2.5mol%; beyond that value, the membrane existed as a composite comprising an O-permeable SrCo0.8Fe0.2O3-δ phase and O-imperious SrSnO3 phase. The inclusion of 15mol% of SrSnO3 phase in SrCo0.8Fe0.2O3-δ gave rise to an increase of sintering temperature from 1100 to 1280C. By exposing a 1.2mm-thick composite to air at one side and flowing He at the other side, O permeated through the membrane at rates of 1.3 x 10-6 and 5 x 10-8mol/cm2s at 1000 and 560C, respectively. The Arrhenius plot of O permeation flux showed a bending at 737C for the composite, about 80C lower than that for the single-phase SrCo0.8Fe0.2O3-δ. Moreover, the O permeability of the composite decreased less pronouncedly with decreasing temperature than that for SrCo0.8Fe0.2O3-δ, especially in the temperature range below the bending point. The composite also showed a reduced thermal expansion compared with SrCo0.8Fe0.2O3-δ, which would improve the mechanical compatibility of the membrane with other components in a membrane assembly.

Preparation and Characterization of SrCo0.8Fe0.2O3-δ–SrSnO3 Oxygen-Permeable Composite Membrane. C.G.Fan, Z.Q.Deng, Y.B.Zuo, W.Liu, C.S.Chen: Solid State Ionics, 2004, 166[3-4], 339-42