Abstract
We report on the structural, temperature, and frequency dependent impedance studies of Ti doped cobalt ferrite material (CoFe1.95Ti0.05O4) in comparison with the pure CoFe2O4. XRD and Raman spectroscopy studies confirm the inverse spinel crystallization of the materials with space group of Fd-3 m. Scanning electron microscope images shows the microcrystalline nature of the particles. Homogeneity, stoichiometry, and ionic states of the ions in the composition were confirmed by energy dispersive X-ray analysis and X-ray photoelectron spectroscopic studies. Temperature and frequency dependent real (Z′) and imaginary (Z″) part of the impedance shows the existence of relaxation processes and their distribution in CoFe2O4 and CoFe1.95Ti0.05O4 materials. Complex impedance spectroscopy studies at low temperatures shows that the conductivity in these materials is predominantly due to the intrinsic bulk grains. With increasing the temperature, evolution of grain boundary conduction is clearly seen through the appearance of a second semi-circle in the complex impedance plots. Room temperature total dc conductivity of both CoFe2O4 and CoFe1.95Ti0.05O4 materials is found to be 5.78 × 10-8 and 1.61 × 10-7 S/cm, respectively. Temperature variation of dc electrical conductivity follows the Arrhenius relationship and the activation energies for CoFe2O4 corresponding to grain (0.55 eV for CoFe2O4), grain boundary (0.52 eV), and total conduction (0.54 eV) are discussed. Observation of well distinguishable grain and grain boundary conductions and the low conductivity values in CoFe2O4 and CoFe1.95Ti0.05O4 materials indicates that these materials are promising candidates for the high frequency applications.