Cationic Order in Double Perovskite Oxide, Sr2Fe1−x Sc x ReO6 (x = 0.05, 0.1)

Abstract

We have synthesized by sol-gel method the following polycrystalline double perovskite samples: Sr2Fe1−x ScxReO6 (x = 0, 0.05, 0.1). The results of the Rietveld refinements presented single double perovskite phases with orthorhombic symmetry for the system Sr2Fe1−x ScxReO6, the differences in atomic radii between Fe3+ and Sc3+ cause a lowering in symmetry with respect to the parent Sr2FeReO6 tetragonal compound. The Curie temperatures are found at about 426 and 436 (±5) K for Sr2Fe0.9Sc0.1ReO6 and Sr2Fe0.9Sc0.05ReO6, respectively. The Mossbauer spectra measured at 77 K show complex hyperfine structures resulting from different magnetic contributions at Fe3+ sites; the average hyperfine field is estimated 50 T and the isomer shift at 0.5 mm/s. At room temperature an intermediate valence state for Fe is also observed.