Electrical conductivity of cobalt-titanium substituted SrCaM hexaferrites

A series of polycrystalline M-type hexagonal ferrites with the composition Sr0.5Ca0.5CoxTixFe12-2xO19 (where x=0.0-0.8) were prepared by the conventional ceramic technique. The electrical conductivity has been measured from 300 to 590 K. The dc conductivity, sigma(dc), exhibited a semiconductor behavior. The negative sign of thermoelectric power coefficient S reveals that all samples are n-type semiconductors. Both sigma(dc), and mobility, mu(d), increases with the substitution of Co2+ and Ti4+ ions, reach maximum at x=0.4 and start decreasing at x > 0.4. Many conduction mechanisms were discussed to explain the electric conduction in the system. It was found that the hopping conduction is the predominant conduction mechanism. For samples with compositional parameter x=0.0 and 0.8, the band conduction mechanism shares in electric conduction beside the hopping process. (C) 2011 Elsevier B.V. All rights reserved.