Surface effect on oxygen permeation through dense membrane of mixed-conductive LSCF perovskite-type oxide

La0.1Sr0.9Co0.9Fe0.1O3−δ (LSCF1991) dense disks with different thicknesses and surface areas were prepared to investigate the contribution of surface reactions and bulk diffusion in oxygen permeation phenomena. The bulk diffusion controlled situation became significant with increasing the membrane thickness, and the surface reaction controlled situation prevailed at smaller surface area. The increase in surface area at the low P(O2) (anode) side was more effective to increase the oxygen permeation flux than that at the high P(O2) (cathode) side. The coating of a porous catalyst layer below the optimum thickness was also effective in enhancing the oxygen permeability due to the increase in surface area, but the coating with too thick layer deteriorated the permeability probably due to the increase in the gas diffusion resistance.