Crystallographic changes and thermal properties of lanthanum–strontium ferromanganites between RT and 700 °C

X-ray powder diffraction was used to determine the crystallographic changes between room temperature (RT) and 700 °C of the (La0.8Sr0.2)(Mn1−yFey)O3±δ perovskites with y=0.2, 0.5, 0.8, 1 which can be considered as possible cathode materials for the ITSOFCs. 0.2, the rhombohedral symmetry was preserved in the whole temperature range. For y=1, a transition from orthorhombic to rhombohedral symmetry occurred at 290 °C. The compounds with y=0.5 and 0.8 were found to be diphasic at RT by combination of both rhombohedral and orthorhombic symmetries. They became only rhombohedral at 80 and 160 °C, respectively. This reversible transition is discussed in terms of iron concentration, vacancy diffusion and oxidation state. results were corroborated by a dilatometric study. The thermal expansion coefficients of these materials show a good compatibility with YSZ, the usual yttria-stabilized zirconia electrolyte.