Effects of Cobalt substitution on the dielectric properties of Li-Zn ferrites

The dielectric properties of Li(0.4-0.5x)Zn(0.2)Co(x) Fe(2.4-0.5x)O(4) ferrites with x varying from 0.0 to 0.1 in steps of 0.02 synthesized by the citrate precursor method have been investigated as a function of composition and temperature. Room temperature dielectric constant studied at 1 kHz showed a decrease with addition of CO(2+) ions. The variation of dielectric constant with temperature was studied at different frequencies, and an increase was observed as the temperature rises. For certain composition, at particular frequency resonance maxima could be observed in the dielectric constant versus temperature curve. The possible mechanisms responsible for the above behaviour are explained. (C) 2008 Elsevier Ltd. All rights reserved.