Oxygen permeation in SrCo0.8Fe0.2O3 − δ membranes with porous electrodes

✍ Scribed by T.H. Lee; Y.L. Yang; A.J. Jacobson; B. Abeles; S. Milner

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 684 KB
• Volume: 100
• Category: Article
• ISSN: 0167-2738
• DOI: 10.1016/s0167-2738(97)00258-0

✦ Synopsis

Measurements of oxygen flux, in the temperature range, 770~870°C on planar membranes of SrCo,,Fe,,,O,_,, consisting of a dense discs -0.1 cm thick modified by coating with porous layers on both sides, yielded an enhancement in the oxygen flux, 77 = 2, compared to the uncoated membrane. When only one side of the disc was coated with the porous layer on the high pressure side of the membrane then n = 1.2, while when the modified side was on the low pressure side then v = 1.4. The observed values of n were explained by a model of diffusion-reaction transport in mixed ionic electronic conductor membranes with porous electrodes, extended to the case of finite thickness of the dense layer. From a fit of the model to the experimental data, values of the surface exchange coefficient, ki,, and ambipolar oxygen ion-electron hole pair diffusion coefficient, D,, were deduced. At 87O"C, ki, = 2.5 X 1O-4 cm/s and D, = 5 X lo-" cm'/s.