Effects of surface modification on the oxygen permeation of Ba0.5Sr0.5Co0.8Fe0.2O3-δ membrane

The surface of Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) membrane was modified by the addition of a porous layer in order to improve the oxygen permeation properties of this material. At 700 degrees C, the oxygen permeation rate of a 120 mu m-thick BSCF sample with a 6.5 mu m-thick porous layer was 3.6 times that of a similar sample with no surface layer. An estimation of the surface area of the applied porous layer indicated that only the 1.1 mu m of the porous layer nearest the membrane had an effect on the oxygen permeation rate. Weight relaxation was performed at 400 degrees C to clarify the enhancement of the surface exchange reaction. The chemical surface exchange coefficient (k(chem)) was 3.1 times larger for the sample with the porous layer coating. The thickness of the porous layer affecting the oxygen permeation rate was estimated by the transmission line model by D-chem and k(chem). (C) 2014 Elsevier B.V. All rights reserved.