Composition and frequency dependent dielectric properties of Li-Mg-Ti ferrites

The frequency and composition dependent properties of mixed Li0.5MgxTixFe2.5-2xO4 (where x=0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) ferrites have been measured at room temperature. The compositional variation of resistivity and dielectric constant indicates the inverse trends with each other. The sample with x=0.4 shows lowest resistivity and highest dielectric constant. The ac resistivity (rho(ae)), dielectric constant (epsilon'), dielectric loss tangent (tan delta) and loss factor (tan delta/mu(i)) of all the samples decrease with increase in frequency exhibiting normal ferrimagnetic behaviour. The sample with x=0.4 shows a maximum at around 1 kHz in the tan delta versus frequency variation. The values of initial permeability (mu(i)) are independent of frequency. The saturation magnetization (Ms) values of the samples are low and decrease with increase in x due to magnetic dilution by Mg2+ and Ti4+ ions. All the observed variations are explained on the basis of Fe2+/Fe3+ ionic concentration as well as the electronic hopping frequency between Fe2+ and Fe3+ ions in the present samples. (C) 2000 Published by Elsevier Science S.A.