Effect of Zinc Concentration on the Structural, Optical, and Magnetic Properties of Mixed Co-Zn Ferrites Nanoparticles Synthesized by Low-Temperature Hydrothermal Method

Zinc-substituted cobalt ferrites Co_1−xZn_xFe₂O₄ (x = 0.0 to 0.7) nanoparticles have been synthesized using the hydrothermal method. The pure cubic spinel powder samples prepared were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. It is found that the lattice parameter increases with Zn substitution. The average crystallite size of the particles decreases gradually from 20 to 10 nm with the increase in Zn-content, which is confirmed by transmission electron spectroscopy micrographs. The direct and indirect band gap of Co_1−xZn_xFe₂O₄ determined from UV–Vis measurements decreases with the increase of Zn concentration. The magnetic properties have been investigated by physical property measurement system and vibrating sample magnetometer. The saturation magnetization increases slightly from 71.38 emu g⁻¹ (x = 0) to 77.59 emu g⁻¹ (x = 0.1), then decrease with the increase in Zn substitution. Nevertheless, the coercivity significantly decreases with Zn concentrations, which can be explained using Yafet–Kittel model and the distribution of Fe³⁺ ions among octahedral and tetrahedral sites in samples. This result is further confirmed by photoluminescence emission spectra.