The permeation of O through dense SrFe0.67Co0.33O3 membranes was measured as a function of temperature, O partial pressure gradient across the membrane and membrane thickness. A maximum O flux of 1.87 x 10-6mol/cm2 was measured at 1000C, with air on the primary side and He on the secondary side of the membrane. Activation energies ranging from 88 to 108kJ/mol were found at 900 to 1000C. At 1000C, with He on the secondary side of the membrane, a critical thickness of about 1.5mm was found; where the rate-limiting step for O permeation changed from surface exchange kinetics to bulk diffusion. The critical thickness appeared to depend upon the temperature and the gradient of O partial pressure across the membrane.

Oxygen Permeation of SrFe0.67Co0.33O3. S.Aasland, I.L.Tangen, K.Wiik, R.Odegard: Solid State Ionics, 2000, 135[1-4], 713-7