X-ray absorption spectroscopy study of the La0.7Ba0.3Mn1-xCoxO3 system

We report the transition-metal (Mn and Co) K-edge X-ray absorption spectros copy (XAS) study of a series of La0.7Ba0.3Mn1-xCoxO3 (0 less than or equal to x less than or equal to 1) samples. Systematic chemical shifts to higher energy with the Co content (x) are observed in both Mn and Co K-edge spect ra. The chemical shift to higher energy in Mn K-edge spectra is caused by t he decreased Mn3+/Mn4+ ratio due to Co substitution of Mn. The Co K-edge sp ectra show that the Co valence is between 2 + and 3 +, which also increases with x. The effect of electronic structures on the physical properties are briefly discussed. (C) 2000 Elsevier Science B.V. All rights reserved.