Mossbauer Spectra Of Fe-57 Nucleus And Valence State Of Cr And Fe Ion In La1-Xcaxcr1-Xfexo3 (X=1/14, 1/13)

La1-xCaxCr1-xFexO3 (x = 1/4, 1/3) are synthesized by wet chemical method and the crystal structure of the compounds belongs to orthorhombic system. Mossbauer spectra of Fe-57 nucleus show that all the iron ions in the compounds are trivalent and in high-spin state. A tight-bending method on the basis of EHMO approximation has been performed to calculate the average valence states of various ions in La3/4Ca1/4Cr3/4Fe1/4O3. The results indicate that the average valence state of chromium ion increases with doping calcium ion, but that of iron ion still is trivalent in the compound. Doping calcium and iron ions may have a certain effect on energy band structure and on conduction mechanism in lanthanum chromite. (C) 2000 Elsevier Science S.A. All rights reserved.