Lu1-xSrxM0.5Fe0.5O3 (0 ≤ x ≤1) perovskites with M = Cr or Mn: X-ray powder diffraction and emission spectroscopy studies

G. TIRAO; F.E. LURGO; S. LIMANDRI; R. CARBONIO

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Conferencia; XVI Latin American Seminary of Analysis by X-ray Techniques ? SARX; 2018

The perovskite family Lu1-xSrxM0.5Fe0.5O3 (0 ≤ x ≤1) with M = Cr or Mn, have been synthesized and characterized. The samples were prepared in polycrystalline form by a wet chemical method. A very reactive precursor was prepared starting from an aqueous solution of the metal ions and citric acid. A systematic study of the crystal structure was performed by X-ray powder diffraction (XRPD) and emission spectroscopy (XES). The XRPD data of Lu1-xSrxCr0.5Fe0.5O3 (0 ≤ x ≤1) were correctly refined using Pbnm orthorombic unit cell, but from x=0.2 an impurity appears: SrCrO4. This is because, the SrCrO3 perovskite can only be synthetized at high pressures (65-70 kbar). On the contrary, the family Lu1-xSrxMn0.5Fe0.5O3 (0 ≤ x ≤1) was obtained pure and was refined using P63/mmc or P63cm (depending on the composition of Sr) hexagonal unit cell. Taking into account that the R site is occupied by Lu3+ and Sr2+ cations, high resolution XES is used to determine the oxidation state of the transition metal cations in the M site of the perovskite and the impurity, with Cr6+ cations. This information can be obtained by measuring changes in some spectral features, such as energy shifts, possible satellite lines, line shapes and relative intensities. For 3d transition elements, the high-resolution Kβ spectrum shows a clear sensitivity to the chemical environment. These spectra were measured using a non-conventional spectrometer with conventional X-ray sources.