Structural Stability and Oxygen Permeation Properties of Sr[sub 3−x]La[sub x]Fe[sub 2−y]Co[sub y]O[sub 7−δ] (0≤x≤0.3 and 0≤y≤1.0)

The structural stability and oxygen permeation properties of with and have been studied at high temperature and in the oxygen partial pressure range atm. These phases have a perovskite-related intergrowth structure with tetragonal symmetry, which does not change with temperature up to 1000°C in the range atm. The oxygen permeation flux of membranes increases with increasing Co content, decreases with increasing lanthanum content, and does not change with time. Measurements of oxygen permeation flux as a function of membrane thickness for at 900°C indicates the oxygen transport is bulk limited for this composition. Assuming that this observation is also valid for other compositions, the ionic conductivity, and the vacancy diffusion coefficient have been estimated. The structural stability and permeation properties of are compared with those of the perovskite phases and © 2001 The Electrochemical Society. All rights reserved.