Spectral, initial magnetic permeability and transport studies of Li0.5-0.5xCoxFe2.5-0.5xO4 spinel ferrite

A series of polycrystalline spinel ferrite with composition Li0.5-0.5xCoxFe2.5-0.5xO4 where (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1) were prepared by the well-known double sintering process to investigate their spectral, initial magnetic permeability and transport properties. The X-ray diffraction analysis showed that all samples have single cubic spinel phase. The lattice parameter a is increased with increasing Co2+ ion substitution. The IR spectrum shows four main absorption bands. The differential thermal analysis (DTA) reveals three principal peaks at 90, 350 degrees C and at Curie temperature, respectively. The thermoelectric power coefficient a has negative sign indicating that the majority charge carriers are electrons. The DC electrical conducting 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. (c) 2004 Elsevier B.V. All rights reserved.