| Two mixed metal oxides systems ;An oxygen permeation apparatus has been successfully constructed. A high temperature sealing system has been developed using gold 'O' rings that allows repeated heating and cooling cycles on a single sample.;Permeation measurements on SCFO with this apparatus confirmed results reported in the literature, but more extensive and reproducible data were obtained. The data analysis offered significant new insights into this membrane system. Contrary to the bulk diffusion permeation model assumed in the earlier work, our results indicate that surface exchange is the rate limiting step for the permeation process in the SCFO system.;BiMeVOX compounds are known to have high ionic conductivities, but most compounds do not have the electronic conductivity needed for permeation membranes. The manganese-doped system was chosen for study because high electronic conductivities were anticipated. Detailed conductivity studies have been made on ;The structural studies using X-ray and neutron diffraction techniques show that the structure of the BiMnVOX compounds are complex. X-ray absorption spectroscopy (XAS) was used to obtain more detailed information on the local coordination environments of the manganese and vanadium atoms. The results provide a basis for the interpretation of the conductivity data. |
