OXYGEN PERMEATION STUDIES OF DIFFUSION AND SURFACE EXCHANGE IN MIXED CONDUCTING OXIDE ELECTRODE MATERIALS

摘要

Oxygen permeation measurements can be used to obtain both oxygen surface exchange and diffusion coefficients for cathode materials. Our previous analysis of results for planar membranes of SrCo_(0.8)Fe_(0.2)O_(3-x) (SCFO) as a function of pO_2, temperature and thickness show that both the surface kinetics and the bulk diffusion determine the oxygen flux. The model has been extended to quantitatively predict the enhancement in oxygen flux observed experimentally when porous electrodes are added to one or both surfaces of the membrane. The permeation flux for a SCFO membrane has also been measured with a tubular geometry, thereby eliminating the need for edge effect corrections.