Polaronic and charge ordering effects in Pr 0.5 Sr 0.5 Mn 1− x Fe x O 3

Abstract

In this work we report the results of X-ray diffraction and Mossbauer spectroscopy for the systems Pr0.5Sr0.5Mn1 − x Fe x O3 (with x = 0.05, 0.10, 0.15, 0.20, 0.25, 0.30). XRD patterns indicated that all samples were single phase with slightly distorted orthorhombic symmetry. Room temperature Mossbauer spectra are all quadrupole split, indicating paramagnetic relaxation of the Fe moment for all values of Fe concentrations. The spectra are fitted with two doublet components associated with Fe3 + ions in octahedral sites with different distortions. Mossbauer spectra recorded at liquid nitrogen temperature for this system also indicate paramagnetic relaxation of the Fe moments down to liquid nitrogen temperature (LNT). In these spectra a third quadrupole component with quadrupole splitting close to zero develops. This component is associated with the delocalization of the charge carriers and the consequent disappearance of lattice distortions produced by the polaronic effect at room temperature. The component with the high quadrupole splitting (0.81 to 1.07 mm/s) results from Jahn–Teller distortion as a consequence of charge ordering transition at low temperature.