Study of Dielectric Properties of Nano-crystalline Mn-Zn Ferrite

Abstract

The ac conductivity σ and dielectric properties (dielectric constant ', dielectric loss '' and loss tangent tan δ) were measured as a function of frequency between 100 Hz and 20 MHz for the mixed ferrites Zn x Mn 1-x Fe 2 O 4 (where x = 0.2 to 0.8), synthesized by solid-state route. The ac conductivity σ below 1 MHz seems to be nearly frequency independent for all compositions; and above these frequency ranges, σ sharply increases until it reaches a maximum value. The relaxation time (τ) was found to be in the range 0.3x10 -5 – 1.5x10 -5 sec from the hopping frequency. The dielectric constant for these ferrites is approximately inversely proportional to the square root of the resistivity. The electrical conduction mechanism was explained in terms of the electron hopping model. The formation of spinel structure and crystalline size was confirmed using X-ray diffraction (XRD) technique. Morphology of the samples was studied using Scanning Electron Microscopy (SEM).