Local structure around Mn atom in the LaMnO3+delta system

Mn K-edge X-ray absorption spectroscopy was used to determine the electroni c and geometrical local structure at the Mn site in LaMnO3+delta (delta = 0 , 0.07, and 0.15) series. The XANES spectra of LaMnO3+delta samples show a mixed valence oxidation state for the Mn atom similar to that found in La1- xCaxMnO3 series. EXAFS spectra show a distorted Jahn-Teller octahedra for L aMnO3 which is drastically reduced as delta increases. Otherwise, an anomal ous structural disorder, reported for the paramagnetic phase in magnetoresi stive compounds, is also present at low temperatures in this series. (C) 19 99 Elsevier Science B.V. All rights reserved.