Magnetic, Dielectric and Electrical Properties of Lithium-Magnesium Ferrites

A series of polycrystalline spinel type ferrites with composition Li _x Mg_0.5Ni_{0.5– 2 x} Fe_{2+ x} O₄, where x = 0.00 to 0.25 in steps of 0.05, have been prepared by standard double sintering method sintered at temperature 1200 °C in air for 6 hours. In this work, investigations have been carried out by the measurements of X-ray diffraction (XRD), Curie temperature, permeability, loss tangent, Q-factor, dielectric constant and ac electrical resistivity of the samples. Some measurements have been done at room temperature while other measurements have been done as a function of temperature and as a function of frequency in the range from 1 kHz to 500 kHz. Curie temperature, the real part of initial permeability (μ _i ), the loss tangent (tan δ), and the Q-factor have been found to be decreased with the increase of Ni-content of Li _x Mg_0.5Ni_{0.5– 2 x} Fe_{2+ x} O₄ ferrites. The frequency characteristic of dielectric constant and AC resistivity decreases with the increase in frequency and increases with the increase in Ni-content.