A case study of the effect of grain size on the oxygen permeation flux of BSCF disk-shaped membrane fabricated by thermoplastic processing

Oxygen permeability measurements of Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-delta) (BSCF) disk shaped membranes fabricated by thermoplastic processing and sintered at different temperatures (1000-1100 degrees C), showed no influence of the grain size on the oxygen permeation fluxes. To further investigations, Electron Backscattered Diffraction (EBSD) and Conductive mode (CM) microscopy methods were used for texture analysis and observation of the local electrical behavior in the BSCF membranes, respectively. EBSD results revealed that the grain size of the membranes increased with increasing the sintering temperature from an average of 3.32 mu m at 1000 degrees C to 18.25 mu m at 1100 degrees C. Also, it was seen that there was no textural difference between the different samples. CM analysis demonstrated that the electronic conductivity of the grains and grain boundaries was similar in the membrane sintered at 1000 degrees C. Finally, the stability of the membrane under the operation conditions was tested, and it was found that the permeation flux was nearly constant at 900 degrees C after an operation time of more than 50 h, whereas oxygen permeation flux declined after a relative short time at 825 degrees C. (c) 2011 Elsevier B.V. All rights reserved.