Valence electronic structure of Mn in undoped and doped lanthanum manganites from relative K X-ray intensity studies

Abstract

Relative K X-ray intensities of Mn in Mn, MnO 2, LaMnO 3 and La 0.7B 0.3MnO 3 (B = Ca, Sr and Ce) systems have been measured following excitation by 59.54 keV γ-rays from a 200 mCi 241Am point-source. The measured results for the compounds deviate significantly from the results of pure Mn. Comparison of the experimental data with the multi-configuration Dirac–Fock (MCDF) effective atomic model calculations indicates reasonable agreement with the predictions of ionic model for the doped manganites except that the electron-doped La 0.7Ce 0.3MnO 3 and hole-doped La 0.7Ca 0.3MnO 3 compounds show some small deviations. The results of MnO 2 and LaMnO 3 deviate considerably from the predictions of the ionic model. Our measured Kβ/Kα ratio of Mn in La 0.7Ca 0.3MnO 3 cannot be explained as a linear superposition of Kβ/Kα ratios of Mn for the end members which is in contrast to the recent proposal by Tyson et al. from their Mn Kβ spectra.