Electrical transport properties of cadmium substituted copper ferrites

Electrical transport properties such as electrical conductivity (sigma) and thermoelectric power (S) of cadmium substituted copper ferrites, forming the chemical formula Cu1-xCdxFe2O4, where x = 0.2, 0.4, 0.6, 0.8 and 1.0 have been investigated from room temperature to well beyond the Curie temperature. Plots of log(sigma T) vs. 10(3)/T are linear and show a transition near the Curie temperature except in the case of cadmium ferrite. Based on the Seebeck coefficient (S), the ferrites under investigation have been classified as n-type semiconductors. The values of charge carrier concentration and mobility have been computed from experimental values of Seebeck coefficient and electrical conductivity. The activation energy in the ferrimagnetic region is in general less than that in the paramagnetic region. An attempt is made to explain the conduction mechanism in these ferrites. The properties of cadmium substituted copper ferrites have been correlated with these of zinc substituted copper ferrites, cadmium and zinc being two non-magnetic divalent ions occupying essentially tetrahedral A sites when substituted in ferrites. (C) 2000 Elsevier Science B.V. All rights reserved.