Structural and magnetic characterizations of Ni-Zn-Co ferrite nanoparticles synthesized by sol-gel autocombustion method

Cobalt substituted Ni-Zn ferrite nanoparticles with the formula, Ni_0.4Zn_0.6-xCo_xFe₂O₄, where x varies from 0.00 to 0.25 in steps of 0.05, were prepared by sol-gel autocombustion method and analyzed for their structural and magnetic properties. The synthesized nanoparticles were subjected to X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy, thermal analysis and magnetic measurements. The X-ray patterns confirm cubic spinel structures with the crystallite sizes in the range from 31.72 nm to 36.87 nm. The particle sizes estimated using electron micrographs are in good agreement with the crystallite sizes obtained from the X-ray data. Infrared data confirms the spinel structure by showing Fe_A-O and Fe_B-O stretching vibrations while the thermal data hints at a slight weight gain due to oxidation. The obtained magnetic data suggests a marginal increase in saturation magnetization with the Co substitution at x = 0.10 and 0.25. The results are analyzed in terms of the compositional and structural modifications, and it was found that the variation of magnetic moment was governed by a corresponding change in the oxygen positional parameter in these materials.