Electrical and magnetic properties of Ni_0.8Zn _0.2Fe₂O₄/silica composite prepared by sol-gel method

Ultrafine Ni_0.8Zn_0.2Fe₂O₄ particles dispersed in silica (SiO₂) matrix are produced by sol-gel method. The powders were subjected to X-ray diffraction to confirm the formation of crystalline phases. The physical properties such as bulk density, true density, % of porosity and % of linear shrinkage were studied. The magnetic permeability as the function of frequency from 1 kHz to 13 MHz and temperatures from room temperature to 300°C were studied for samples sintered at temperature 1250°C. The AC electrical resistivity as the function of frequency and DC electrical resistivity as the function of temperature were studied. The AC-resistivity of the order of ≥10⁵ Ωcmand DC-resistivity ≥ 10⁸ Ωcm were obtained at room temperature. Microstructural features of sintered samples show the presence of ferrite grains of 1-2 μm size.