Covalency and Racah parameters of Fe3+ in Mn–Zn–Cr nanoferrites

Abstract This study presents the covalency and Racah parameter (B) of Fe3+ in Mn–Zn–Cr nanoferrites, which prepared by citrate–nitrate combustion method. Racah parameter was determined from the spectral data. The bands in the range of interest in optical absorbance are wide and asymmetric; a deconvolution (deconvolution to their component bands) of the experimental spectra becomes compulsory. Further, these spectra were employed to obtain Racah parameter. Racah parameter was decreased, with further Fe addition, from 540 to 441 cm-1. Also, nephelauxetic ratio ( β ) was decreased from 0.532 to 0.435. This denotes that the bonds of Fe3+ and its surroundings become more covalent (the covalency is increased).