Impedance spectral analysis and scaling behavior of Mn2+–Si4+ substituted Mn–Zn ferrites

Abstract

This communication reports complex impedance (Z* = Z′ − iZ″) spectral analysis of polycrystalline spinel ferrite system, Mn0.7+xZn0.3SixFe2−2xO4 (x = 0.0–0.3), synthesized by a solid-state reaction route over the broad frequency (f = 20 Hz–1 MHz) and temperature (T = 300–673 K) ranges. Variation of Z′(f, T) showing a typical negative temperature coefficient of resistant type behavior. Cole-Cole plots (Z″ versus Z′) have been used to determine grain and grain boundary resistances, capacitances, relaxation frequencies and relaxation times. Relaxation time is found to decrease with temperature and it obeys the Arrhenius relationship. The corresponding activation energy values are found to be about ~0.6 eV suggesting conduction due to the polaron hopping based on the electron carriers. Evidence of the components from both localized and delocalized relaxations is observed. The scaling of Z″/Zmax by using fmax as a scaling parameter is more successful as compared to that carried out using σdc as a scaling quantity. The results revealed that the complex dielectric parameters and structure of the ferrite ceramics are strongly coupled properties.