Spectral studies of Co substituted Ni–Zn ferrites

The spinel ferrites Zn0.35Ni0.65−xCoxFe2O4, 0≤x≤1, have been prepared using the standard ceramic technique. Room temperature Mössbauer, X-ray and infrared IR spectra were used for carrying out this study. X-ray patterns reveal that all the samples have single-phase cubic spinel structure. The Mössbauer spectra of the samples show a paramagnetic phase for x=0 and a six-line magnetic pattern and a central paramagnetic phase for x≥0.1. They are analyzed and attributed to two magnetic subpatterns and two quadrupole doublets due to Fe3+ ions at the tetrahedral A-sites and octahedral B-sites. Four absorption bands are observed in IR spectra. They confirm the spinel structure of the samples and existence of Fe3+ ions in the sample sublattices. The deduced hyperfine interactions, lattice parameters, absorption band positions and intensities and force constant are found to be dependent on the substitution factor x, where the cation distribution is estimated. The hyperfine magnetic fields, magnetization and lattice resonant frequency are found to be dependent on the interionic distance.

► Ni–Zn–Co spinel ferrimagnetic properties appear and increase with substitution x≥0.1. ► They are affected by interionic distance and crystallite size. ► The lattice parameters, IR band properties and force constants are x dependent. ► The Co2+ ions distribute between the A- and B-sites with ratios more than Ni2+ ions. ► IR spectra revealed the existence of Fe2+ ions in the sample sublattices.