Synthesis and hydrogen permeation properties of membranes based on dense SrCe0.95Yb0.05O3−α thin films
Abstract Dense SrZr 0.95 Y 0.05 O 3− α and SrCe 0.95 Yb 0.05 O 3− α thin films with perovskite structure were prepared on porous SrZr 0.95 Y 0.05 O 3− α substrates by spin coating colloidal suspensions of powders prepared by combustion methods. Porous substrates were prepared by treating carbon/SrZr 0.95 Y 0.05 O 3− α composites in air at 1273–1573 K in order to combust the carbon 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 N 2 at 900–1000 K. H 2 permeation rates through SrCe 0.95 Yb 0.05 O 3− α thin films at 950 K were as high as 500 times larger than on 1-mm disks and reached values of 6×10 −4 mol H 2 /cm 2 min for 2 μm films. H 2 permeation rates were proportional to the inverse of the membrane thickness, indicating that permeation in SrCe 0.95 Yb 0.05 O 3− α thin films is controlled by bulk diffusion and not by H 2 dissociative chemisorption or by boundary layer transport, even for 2 μm films.