Investigation of structural and magnetic properties of NixZn1-xFe2O4/SiO2 (0≤x≤1) spinel-based nanocomposites

The structural and magnetic properties of NixZn1-xFe2O4/SiO2 nanocomposites (NCs) synthetized using a modified sol-gel method were investigated. The formation of Ni-, Zn- and Fe-succinate precursors (< 200 degrees C) and their decomposition into ferrites (< 400 degrees C) was confirmed by the thermal analysis and Fourier transformed infrared spectroscopy. The transmission electron microscopy images revealed spherical shape nanoparticles of size increasing with the annealing temperature. According to X-ray diffraction, by annealing at 1200 degrees C, highly crystalline single-phase ferrite in samples with high Ni content and crystalline ferrite together with SiO2 in samples with low Ni and high Zn content were evidenced. A linear dependence of crystallite size, lattice parameter, X-ray density and porosity on the Ni content of NCs was observed. The magnetic properties such as saturation magnetization (M-s), remanent magnetization (M-r), coercivity (H-c) and anisotropy (K), also were found to be dependent on the Ni content in NCs. The shape of hysteresis loops indicated a superparamagnetic and ferromagnetic behavior of the obtained NCs.