Temperature dependence of electrical conductivity and dielectric properties in Li-Mn ferrite

Manganese substituted lithium-ferrite with the general formula Li0.5-0.5xMnxFe2.5-0.5xO4 (where x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) were synthesized by the standard ceramic technique. The variation of DC and AC conductivities has been reported as a function of temperature from room temperature (293 K) up to 970 K in static air. AC measurements were carried out over a wide range of frequencies from 100 Hz up to 1 MHz. The variation ln sigma at room temperature with composition indicates that the conductivity initially increases up to 0.5 and then decreases with further addition in Mn content. The activation energy of the conduction mechanism decreases from 0.68 to 0.34 eV. The electrical conductivity in the present ferrite is explained on the basis of the hopping mechanism. Dielectric properties, such as dielectric loss tangent, tan delta, and dielectric constant, epsilon', have been measured. The dielectric behavior is explained by using the mechanism of the polarization process.