Ferrimagnetic to paramagnetic transition and dielectric relaxation in Ni_1-xZn_xFe₂O₄ ferrites

Abstract

The spinel ferrite system Ni_1-xZn_xFe₂O₄ (x=0-0.7, Δx=0.1) was prepared by wet chemical co-precipitation method using sulfates of respective metal ions. The electrical resistivity and dielectric properties of the prepared samples have been studied as a function of temperature, frequency, and Zn content (x). The DC resistivity (ϱ) was measured in the temperature range of 300 to 800 K. The curves so plotted show two phases viz. ferrimagnetic and paramagnetic, wherein the transformation from former to later phase took place at the Curie temperature, T_C. The values of T_C were found to decrease with the increase in x. The values of activation energy (ΔE<0.2 eV) depicted the possibility of the hopping mechanism governing the conduction within the ferrites. The ferrite samples exhibited semiconducting behavior, where the electrical resistivity (ρ) decreased with the increasing temperature. The dielectric constant (ε’) and dielectric loss (ε”) were studied as a function of composition, temperature, and frequency.

Keywords:
wet chemical co-precipitation method; DC resistivity; ferrimagnetic phase; paramagnetic phase; Curie temperature; dielectric properties