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 t he chemical formula Cu1-xCdxFe2O4, where x = 0.2, 0.4, 0.6, 0.8 and 1.0 hav e been investigated from room temperature to well beyond the Curie temperat ure. Plots of log(sigma T) vs. 10(3)/T are linear and show a transition nea r the Curie temperature except in the case of cadmium ferrite. Based on the Seebeck coefficient (S), the ferrites under investigation have been classi fied as n-type semiconductors. The values of charge carrier concentration a nd mobility have been computed from experimental values of Seebeck coeffici ent 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 propert ies of cadmium substituted copper ferrites have been correlated with these of zinc substituted copper ferrites, cadmium and zinc being two non-magneti c divalent ions occupying essentially tetrahedral A sites when substituted in ferrites. (C) 2000 Elsevier Science B.V. All rights reserved.