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Polycrystalline mixed Cu-Zn spinel ferrites with general formula Cu 1-x Zn x Fe 2 O 4 (x = 0.0, 0.1, 0.3, 0.5 and 0.7) have been prepared by solid-state reaction method. The effect of Zn 2+ ions on transport properties such as DC and AC resistivity, dielectric constant and dielectric loss tangent has been presented in this paper. The resistivity increases with Zn content and decreases with frequency which have been explained by Verway's hopping mechanism. Decrease of DC electrical resistivity with increasing temperature has been observed and activation energy has been found to increase with increasing Zn content. The dielectric constant is found to decrease with increasing Zn content as well as increasing of frequency has been explained on the basis of space charge polarization. In this communication, an attempt has been made to explain the conduction mechanism of Cu-Zn ferrites on the basis of electronic hopping frequency between Fe 2+ and Fe 3+ ions.

Cu-Zn ferrites of composition Cu 1-x Zn x Fe 2 O 4 were prepared by double sintering ceramic technique at 950 0 C and 1050 0 C for 3 hours and 2 hours, respectively. Structural and magnetic properties of the Cu-Zn ferrites were investigated by using X-ray diffraction, microstructure study and complex permeability behaviour. X-ray analysis indicated the formation of single-phase cubic spinel structure for all samples. The lattice parameter was found to increase with increasing Zn content obeying Vegard's law. The X-ray and bulk densities of the Cu-Zn ferrite significantly decreased whereas porosity increased with increasing Zn concentration. Micrographs exhibited decrease in grain size with increasing concentrations. The real part μ'of initial permeability remained constant up to certain lower range of frequency after which it decreased to lower value of permeability. μ' increased with increasing Zn contents up to x = 0.5, after that it decreased with higher Zn content but was also found to increase with sintering temperature. The possible reasons responsible for change in structural, microstructural and complex permeability with increasing of nonmagnetic Zn 2+ ion are ascertained.

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