Electric, dielectric, and thermoelectric properties of zinc substituted Ni-Mg ferrites

Abstract

The electric, dielectric, and thermoelectric properties have been studied for a series of Zn_xMg_0.8–xNi_0.2Fe₂O₄ ferrite samples (with x = 0, 0.2, 0.4, 0.6, and 0.8) prepared using the usual ceramic technique. The experimental results indicated that the real dielectric constant ε′ and dielectric loss factor tan δ decrease whereas the ac electrical conductivity σ₂ (ω, Τ) increases on increasing the angular frequency ω. The negative sign of the thermoelectric power α indicated that the majority of charge carriers are electrons (in type semiconductor) for all samples. The drift mobility μ and α increase as the temperature increases. The dc ((Jσ_dc(T) ) and real ac <disp-formula><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="splitsection9-m1.tif"/></disp-formula> electrical conductivity, ε′ tan δ, and μ increase whereas the activation energy for drift mobility E_H decreases as Zn ion substitution increases. The parameters nand B for electric conductivity σ₂ (ω, Τ) were found to be composition dependent, both nand B increasing as Zn ion substitution increases. Empirical formulae are suggested for the composition dependencies of electrical conductivity σ, exponent n, parameter B, and activation energy E_H.