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

Relative K x-ray intensities of Mn in Mn, MnO2, LaMnO3 and La0.7B0.3MnO3 (B = Ca, Sr, and Ce) systems have been measured following excitation by 59.54 keV γ-rays from a 200 mCi Am point-source. The measured results for the compounds deviate significantly from the results of pure Mn. Comparison of the experimental data with the multiconfiguration DiracFock (MCDF) effective atomic model calculations indicates reasonable agreement with the predictions of ionic model for the doped manganites except that the electron doped La0.7Ce0.3MnO3 and hole doped La0.7Ca0.3MnO3 compounds show some small deviations. The results of MnO2 and LaMnO3 deviate considerably from the predictions of the ionic model. Our measured Kβ/Kα ratio of Mn in La0.7Ca0.3MnO3 cannot be explained as a linear su1 perposition 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. Our result for La0.7Ca0.3MnO3 suggests an admixture of Mn 2+ state in agreement with the earlier proposals regarding Mn disproportionation.