High resolution x-ray absorption near edge structure at the Mn K edge of manganites

We report a systematic study of manganese perovskites, RE1-xDxMnO3 (RE = rare earth; D = Ca, Sr), by means of x-ray absorption near edge structure (XANES) spectroscopy at the Mn K edge. High resolution has been achieved by recording the intensity of the Mn Kβ fluorescence spectrum. All the samples show a unique resonance at the Mn K edge. This common feature does not depend on small changes in the local structure around the Mn atom. The XANES spectra of mixed (0<x<1) composition compounds cannot be obtained by linear combination of REMnO3 and DMnO3 spectra. Therefore, Mn3+ and Mn4+ ions cannot be distinguished in intermediate RE1-xDxMnO3 compounds, either spatially or temporally. The possibility of a charge disproportionation is also considered and discussed in the paper. (author)