Dense SrZr0.95Y0.05O3-α and SrCe0.95Yb0.05O3-α thin films with perovskite structure were prepared on porous SrZr0.95Y0.05O3-α substrates by spin coating colloidal suspensions of

powders prepared by combustion methods. Porous substrates were prepared by treating C/SrZr0.95Y0.05O3-α composites in air at 1273 to 1573K in order to combust the C and partially sinter the resulting porous oxide. This procedure led to strong porous solids with a high gas permeability. Matching the shrinkage of the porous substrate and of the thin film by this pre-sintering of the porous substrate led to thin films free of fissures and other defects. Thin films prepared by these methods did not transport He at ambient temperature or N2 at 900 to 1000K. H2 permeation rates through SrCe0.95Yb0.05O3-α thin films at 950K were as high as 500 times larger than on 1mm disks and reached values of 6 x 10-4molH2/cm2min for 2μm films. H2 permeation rates were proportional to the inverse of the membrane thickness, indicating that permeation in SrCe0.95Yb0.05O3-α thin films was controlled by bulk diffusion and not by H2 dissociative chemisorption or by boundary layer transport, even for 2μm films.

Synthesis and Hydrogen Permeation Properties of Membranes Based on Dense SrCe0.95Yb0.05O3-α Thin Films. S.Hamakawa, L.Li, A.Li, E.Iglesia: Solid State Ionics, 2002, 148[1-2], 71-81