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 gamma -rays from a 200 mCi(241)Am point-source, The measured results fo r the compounds deviate significantly from the results of pure Mn. Comparis on of the experimental data with the multiconfiguration Dirac-Fock (MCDF) e ffective atomic model calculations indicates reasonable agreement with the predictions of ionic model for the doped manganites except that the electro n-doped La0.7Ce0.3MnO3 and hole-doped La0.7Ca0.3MnO3 compounds show some sm all deviations. The results of MnO2 and LaMnO3 deviate considerably from th e predictions of the ionic model. Our measured K beta /K alpha ratio of Mn in La0.7Ca0.3MnO3 cannot be explained as a linear superposition of K beta / K alpha ratios of Mn for the end members which is in contrast to the recent proposal by Tyson et al, from their Mn KP spectra. (C) 2001 Elsevier Scien ce B.V. All rights reserved.