Effect of calcination temperature on the structural and electrical properties of cobalt ferrite synthesized by combustion method

In this paper, the structural and electrical properties of cobalt ferrite synthesized by combustion route with hexamine as a fuel are reported for the first time. Thermogravemetric analysis (TGA) confirm the stable phase formation of the phase above 700 degrees C. Structural characterizations of all the samples were carried out by X-ray diffraction (XRD) technique. It reveals an increase in the particle size with the calcination temperature (i.e. 700,800 and 900 degrees C). Infrared (IR) spectroscopy confirms the presence of tetrahedral and octahedral group complexes within the spinel lattice. DC resistivity as function of temperature indicates that all the samples obey the semiconducting behavior and it decreases with calcination temperature. The variation of dielectric constant (epsilon(r)) and ac conductivity (sigma(ac)), for all the samples have been studied as a function of applied frequency in the range from 20 Hz to 1 MHz. The dielectric constant increases with the calcination temperature and all the samples exhibit usual dielectric dispersion which is due to the Maxwell-Wagner-type interfacial polarization. The ac conductivity measurement suggests that the conduction is due to small polaron hopping. (C) 2010 Elsevier B.V. All rights reserved.