The influence of Zn ions substitution on the transport properties of Mg-ferrite

The thermoelectric power and electrical conductivity measurements of Zn-substituted Mg-ferrites having the general formula Mg(1-x)Zn(x)Fe(2)O(4) (where x = 0, 0.2, 0.4 and 0.6) were carried out from room temperature to 773 K. The Seebeck coefficient is positive for all the compositions showing that these ferrites behave as p-type semiconductors and the majority charge carriers are holes. The temperature variation of the Seebeck coefficient is also discussed. The Fermi energy (E(F)); the density of charge carriers (n) and the carriers mobility (mu) were determined for the studied system. The variation of log sigma with reciprocal of temperature shows a discontinuity at Curie temperature. The DC electrical conductivity increases with increasing temperature ensuring the semiconducting nature of the samples. The Curie temperature determined from DC electrical conductivity was found in satisfactory agreement with that determined from initial magnetic permeability measurements. This transition temperature is found to decrease with increasing Zn concentration. The activation energy in the paramagnetic region is found to be lower than that in ferrimagnetic region. The variation of room temperature conductivity with composition indicates that conductivity increases with increasing Zn content. The dependence of the electrical conductivity of Mg-Zn ferrite on Zn content is explained on the basis of the cation distribution. (C) 2009 Elsevier B.V. All rights reserved.