The perovskite-type Sr0.97Ti0.60Fe0.40O3 was studied by using O permeation, Faradaic efficiency and total electrical conductivity measurements at 973 to 1223K. The ion transference numbers in air varied from 0.005 to 0.08, and decreased with decreasing temperature. The electron-hole conductivity was relatively low, but exceeded the ionic conductivity. The activation energy for electronic conduction was equal to 35kJ/mol at 470 to 890K, but fell at higher temperatures. A study of O permeation through dense Sr0.97Ti0.60Fe0.40O3 ceramic membranes, as a function of membrane thickness, showed that - at temperatures above 1170K - the permeation flux was limited by both bulk ionic conduction and surface exchange rates. The deposition of porous layers of the same material (or of a mixture of Pt and Pr oxide) onto the feed-side surface led to a significant increase in the O permeability. Decreasing the temperature resulted in an increased importance of bulk ionic transport as the permeation-determining factor. The O permeation fluxes at 1073K were limited mainly by the O-ion conductivity of the ceramic.

Faradaic Efficiency and Oxygen Permeability of SrTiFeO3 Perovskite. V.V.Kharton, A.V.Kovalevsky, A.P.Viskup, F.M.Figueiredo, J.R.Frade, A.A.Yaremchenko, E.N.Naumovich: Solid State Ionics, 2000, 128[1-4], 117-30