Structural, thermal and dielectric studies of mixed spinel CoFe2O4

Abstract

In the present work, the phase development and dielectric response of polycrystalline CoFe2O4 has been studied as a function of temperature. The CoFe2O4 was synthesized by solid state reaction technique. The thermal activation of the reactions between precursors were studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA) to optimize the calcination temperature. The structural studies performed by X-ray diffraction followed by Rietveld refinement shows that CoFe2O4 crystallize in cubic Fd-3 m, conforming to a mixed spinel structure (Co0.95Fe0.05) (Fe0.975Co0.025)2O4. The dielectric studies show a low frequency dispersion, predominantly associated with the Maxwell-Wagner polarization. The real part of ac conductivity, σ' shows a change of ~ 4 orders in magnitude and follows the modified Jonscher’s law. The derived values of σdc, comply with Arrhenius behavior with the activation energy of ~ 0.382 eV. The values of exponents range from 0 to 1, indicating the conductivity in measured range is dominated by hopping of charge carriers.