Dielectric Properties of Nano Crystalline Cobalt Substituted Lithium Ferrites by Citrate-gel Auto Combustion Method

Nano-Crystalline Cobalt substituted Lithium ferrites having the compositional formula [Li0.5Fe0.5]1-xCox Fe2O4 (where x=0.0, 0.2, 0.4, 0.6, 0.8 and, 1.0) were prepared by Citrate- Gel Auto Combustion method at low temperature (180°C). The prepared powder samples were sintered at 500°C for 4hours. X-ray diffraction (XRD) analysis reveals that all the samples posses a single phase cubic spinel structure. The surface morphology of the samples was observed by field emission scanning electron microscopy (FESEM). The dielectric parameters such as dielectric constant (ε’), dielectric loss tangent (tan δ) and AC conductivity (σAC) of the samples were studied as a function of frequency in the range of 20Hz to 2M Hz at room temperature using Agilent E 4980 Precession LCR Meter. The dielectric constant, loss tangent and AC conductivity (σAC) of the samples show a normal dielectric behavior with frequency which reveals that the dispersion is due to the Maxwell-Wagner type interfacial polarization and hoping of electrons between the Fe+2 and Fe+3 ions.