Dielectric properties and impedance analysis of polycrystalline Li-Si ferrite prepared by high energy ball milling technique

The effect of Si substitution on the ac electrical conductivity, dielectric and impedance properties of Li0.5+0.5xSixFe2.5−1.5xO4 (0 ≤ x ≤ 0.6) ferrite synthesized by high energy ball milling technique has been reported. The ac measurements were performed over a wide range of frequencies from 100 Hz up to 1 MHz and as a function of temperature from room temperature up to 960 K. Ac electrical conductivity as a function of frequency and temperature exhibited a semiconducting behavior. Small polaron hopping conduction mechanism has been observed in all compositions. For the samples with x = 0.0 and 0.1, the correlated barrier hopping mechanism was noticed at first, followed by the small polaron hopping conduction mechanism. The dielectric constant έ and dielectric loss ε″ decrease with increasing frequency and remain constant at higher frequencies, showing the usual dielectric dispersion. The dispersion of the dielectric properties was discussed through Koop's phenomenological theory. The low dielectric loss tangent at higher frequencies makes the opportunity of these ferrites for high frequency applications. The impedance spectroscopy technique was utilized to investigate the effect of grain and grain boundary on the electrical properties of the present series.