ABSTRACT
For ceramic oxygen membranes the membrane thickness is a key parameter for achieving high oxygen permeation rates. The ability to fabricate thin membranes, typically 10-50 μm, on porous mechanical supports is thereby often of vital importance. We here report on the fabrication and oxygen permeation rates of mixed conducting CaTi_0.9Fe_0.1O3-δ membranes. Submicron powder of CaTi_0.9Fe_0.1O3-δ was prepared by spray pyrolysis, and shaped into symmetrical membranes, using conventional powder pressing with sintering, and asymmetric membranes, using tape casting. The oxygen permeation rates has been characterised as a function of membrane thickness (1500-30 μm), temperature (800-1050°C) and gradient in oxygen chemical potential. Within the experimental temperature and thickness range, the oxygen flux increases approximately proportional to the inverse membrane thickness, in accordance with the Wagner equation. Thus, the oxygen permeation rate is primarily limited by bulk diffusion.