Effect of Li substitution on the magnetic properties of LixMg0.40Ni0.60−2xFe2+xO4 ferrites

Structural and magnetic properties of a series of polycrystalline spinel type ferrites with the nominal chemical composition LixMg0.40Ni0.60−2xFe2+xO4, where x=0.0–0.3 in steps of 0.05, were investigated thoroughly. The formation of spinel structure was confirmed by X-ray diffraction analysis. Lattice constants and average grain diameters increased with increase in Li content. The real part of the initial permeability (μ/i) is found to increase not only with increase in Li content up to x=0.25 but also with the increase in sintering temperature up to 1100 °C. However, it decreases for further increase in sintering temperature except for x=0 and 0.05 compositions. The grain size dependent μ/i is also observed clearly in this research. From the magnetization as a function of applied magnetic field plots, it is clear that all samples exhibit ferrimagnetic state at room temperature and have a low saturation field. The magnetization obtained is explained with the help of redistribution of cations in the tetrahedral and octahedral sites and spin canting due to weakening of exchange interaction.