Oxygen transport in La1−xSrxFe1−yMnyO3−δ perovskites

The oxygen transport in La1−xSrxFe1−yMnyO3−δ (LSFM) with 0≤x≤0.5 and y=0.2 and 0.3 has been examined with a thermogravimetric method. As long as x≤y, the oxygen transport was found to be very slow while the oxygen transport increased several orders of magnitude when x>y. For two compositions—La0.5Sr0.5Fe0.7Mn0.3O3−δ (I) and La0.6Sr0.4Fe0.8Mn0.2O3−δ (II)—oxygen chemical diffusion coefficients were determined and found to increase from 1.5×10−5 to 5.6×10−5 cm2 s−1 for composition (I) and from 1.4×10−6 to 1.4×10−4 cm2 s−1 for composition (II) in the temperature range 750–1000 °C. The activation energy for the oxygen chemical diffusion was found to be 66 kJ mol−1 for La0.5Sr0.5Fe0.7Mn0.3O3−δ and 136 kJ mol−1 for La0.6Sr0.4Fe0.8Mn0.2O3−δ. The oxygen surface exchange constants were found to vary between 2.5×10−4 and 1.8×10−2 cm s−1.