Chemical diffusion in perovskite cathodes of solid oxide fuel cells: the Sr doped LaMn1−xMxO3 (MCo, Fe) systems

This paper reports the results of chemical diffusion coefficient measurements for oxygen in (La,Sr)(Mn,Co)O3 and (La,Sr)(Mn,Fe)O3 using a manometric method in the temperature range of 773 to 1023 K. It was observed that the addition of Fe or Co into (La4xSrx)1−yMnO3 results in a substantial increase of the chemical diffusion coefficient. In the range 25–100 mol% of Co or Fe substitution at B-site in (La,Sr)MnO3, the chemical diffusion coefficient exhibits much lower activation energy than that in (La,Sr)MnO3. The chemical diffusion data in (La,Sr)(Mn,Co)O3 and (La,Sr)(Mn,Fe)O3 system determined by the manometric method are generally in agreement with those determined by electrochemical relaxation methods reported in the literature. A comparison of the chemical diffusion data indicates that the oxygen mobility is lowest in (La,Sr)MnO3 and highest in (La,Sr)CoO3.