Oxygen transport in La0.5Sr0.5Fe1−yTiyO3− δ ( y =0.0, 0.2) membranes
Bayraktar, Defne ; Diethelm, Stefan ; Holtappels, Peter ; Graule, Thomas ; Van herle, Jan
In: Journal of Solid State Electrochemistry, 2006, vol. 10, no. 8, p. 589-596
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- The influence of partial substitution of Fe with Ti on the oxygen transport properties of La1−x Sr x FeO3 membranes was investigated in view of their application for oxygen separation. Samples of composition $$ La_{{0.5}} Sr_{{0.5}} {\text{Fe}}_{{1 - y}} {\text{Ti}}_{y} {\text{O}}_{{3 - \delta }} $$ (y=0, 0.2) were prepared and their oxygen transport properties characterised by potential step relaxation and by oxygen permeation measurement in an air/argon gradient. With the first technique, chemical diffusion $${( {\widetilde{D}} )}$$ and surface exchange (k S) coefficients were obtained by fitting of the current relaxation data to a single expression valid over the complete time range. The Ti-substituted composition gave slightly larger values of $${\widetilde{D}}$$ and k S. The trend was opposite for the measured oxygen permeation flux. In the latter experience, ordering of oxygen vacancies was observed at lower temperature, reducing significantly the performance of the material