Influence of V2O5 additions on the permeability and power loss characteristics of Ni-Zn ferrites

Poly crystalline nickel-zinc ferrites with the chemical formula, Ni0.65Zn0.35Fe2O4 + xV(2)O(5), where x values range from 0.0 to 1.5 wt.% in steps of 0.3 wt.%, have been prepared by conventional ceramic technique. The samples were sintered for 4 h in air at 1210 degrees C. The XRD analyses of the samples confirm single phase cubic spinel structures. Micrographs of the materials reveal that vanadium additions resulted in fine grain structures with small pores trapped inside the grains as the vanadium concentration increases. Complex permeability of these ferrites exhibit stable frequency responses up to 7 MHz beyond which the real part decreases sharply and the imaginary part increases to have a peak at the relaxation frequency. Power loss has been found to be quite low for these materials up to 3 MHz, thereafter it increases steeply due to large eddy current losses. The results are explained in terms of the compositional and microstructural modifications brought about by the vanadium additions. (c) 2006 Elsevier B.V. All rights reserved.