Abstract
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 (mu(l)(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 degrees C. However, it decreases for further increase in sintering temperature except for x=0 and 0.05 compositions. The grain size dependent mu(l)(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. (C) 2011 Elsevier B.V. All rights reserved.