Ce-substituted Lithium Ferrite: Preparation and Electrical Relaxation Studies

Ce-substituted lithium ferrite, Li0.5CexFe2.5−xO4 (x = 0, 0.05 and 0.1) compositions were synthesized from metal nitrates and citric acid by the solution combustion process by keeping the oxidizer to fuel ratio at unity. The thermal decomposition process was investigated by thermogravimetry-differential thermal analysis, which showed a stable phase formation above 600 °C. The phase composition and molecular bonding of Li0.5CexFe2.5−xO4 were characterized by X-ray powder diffraction analysis and Fourier transform infrared spectroscopy, respectively. An extensive study of electrical relaxation process has been represented with impedance and modulus as a function of frequency at different temperatures. The activation energy obtained from both the formalisms was found to be equal within the error. The dc conductivity and hopping frequency were thermally activated and their activation energies were found to be in the range of 0.69-0.64 eV for x = 0.05. The scaling of modulus and impedance were used to understand the electrical relaxation behaviour of the compositions and they suggest the time temperature superposition principle.