Abstract
A series of perovskites Sr3–xCaxFe2TeO9 (0 ≤ x ≤ 1) have been prepared in polycrystalline form by solid–state reaction method in air. These materials have been studied by X–ray powder diffraction method (XRPD) and Raman spectroscopy. An analysis of the XRD patterns at room temperature has shown that these compounds crystallize in a tetragonal system, space group I4/m. The structure contains alternating (Fe/Te)2aO6 and (Fe/Te)2bO6 octahedra, tilted in anti–phase in the basal ab–plane. The study of Raman spectroscopy at various temperatures shows a transition from tetragonal to cubic phase: I4/m → Fm3¯m. This phase transition occurs at high–temperature. Analysis of Raman spectra recorded at several temperatures shows that this phase transition appears near ∼375 °C for (x = 0), ∼435 °C for (x = 0.5) and ∼451 °C for (x = 1). A proportional and gradual increase of temperature phase transition is observed as function of the calcium amount.
Published Version
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