Permeation experiments were carried out on dense mixed-conducting membranes (0.2 to 2mm) of Bi1.5Er0.5O3, which contained 10, 27.8 or 40vol%Ag, at temperatures ranging from 873 to 993K, under O partial pressures ranging from 10-3.5 to 1bar. It was found that the O flux increased with increasing Ag content. In the case of samples with a non-percolative Ag phase (10 or 27.8vol%Ag), an increased O flux relative to that of the pure oxide was attributed to the more rapid kinetics of surface O exchange in the presence of Ag. The percolative nature of the Ag phase in the 40%Ag material enhanced the ambipolar diffusion of O and electrons. High O fluxes, of the order of 0.25mol/m2s at 873K, were detected for this composition. The activation energy for O permeation at temperatures ranging from 848 to 1003K was between 85 and 95kJ/mol for specimens without percolation, and was equal to 115kJ/mol for the sample with 40vol%Ag. This difference was attributed to a change in the rate-limiting process.

J.E.ten Elshof, N.Q.Nguyen, M.W.den Otter, H.J.M.Bouwmeester: Journal of the Electrochemical Society, 1997, 144[12], 4361-6