The impact of cation distribution on the structural and magnetic properties of nonstoichiometric Co_(0.5)Ni_(0.5+x)Fe_(2-x)O_4 nanoferrites

摘要

In this work, the impact of nonstoichiometric substitution of Fe~(3+) cations by Ni~(2+) ones on the structural and magnetic properties of Co_(0.5)Ni_(0.5+x)Fe_(2-x)O_4 nanoferrites (0.0 < x < 0.4) synthesized by citric autocombustion method has been investigated. The single cubic phase for samples sintered at 600 °C was verified by XRD patterns and FTIR spectra. The crystallite size and microstrain were deduced using Williamson-Hall method, with the former ranging from 55 to 89 nm, in agreement with the TEM microimaging. Hysteresis loops traced via VSM prevailed a regular reduction of the saturation magnetization with Ni~(2+) substitution. A cation distribution has been suggested for each sample based on the experimental data of XRD, FTIR, and VSM. The suggested cation distribution successfully explained the recorded data of lattice parameter, crystallite size, IR frequencies, magnetization and coercivity. Besides the experimental data, the cation distribution supports the compensation of the nonstoichiometric substitution by the appearance of higher valance states of Fe, Ni, and Co cations.