CONICET | Buscador de Institutos y Recursos Humanos

Rare earth perovskites of an RMO3 composition, where R is a lanthanide and M is Fe, Cr or Mn, have been under exhaustive study for several decades. This is because materials with transition metals and rare earth ion (with unpaired d and f electrons, respectively) show a variety of striking effects resulting from the coupling between the two magnetic sublattices. 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: SrCrO41. This is because, the SrCrO3 perovskite can only be synthetized at high pressures (65-70 kbar)2.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. 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 environment3. These spectra were measured using a non-conventional spectrometer with conventional X-ray sources.