Impedance spectroscopy of NiCrxFe2-xO4 polycrystalline ferrite

Abstract

Nano-sized spinel ferrites with the generic formula MeFe2O4 are very important materials because of their interesting structural, electric and magnetic properties as well as their chemical and thermal stabilities. Spinel ferrites have exceptional potential applications in many fields, such as satellite communication, memory devices, filters, microwave absorbing materials, computer components, antenna rod, magnetic recording media, ferro-fluids, transformer cores, cancer treatment, and magnetic resonance imaging. Among others, the ferrite NiFe2O4 has been the subject of extensive technical and fundamental study both in its pure form as well as its substituted form in which various isovalent and non-isovalent metals are made to replace the Fe3+ ions. The synthesis of ferrite nanoparticles through the sol-gel auto-combustion (SGA) method is a unique combination of the ignition and chemical gelation processes. This method has the advantages of simple preparation, cost-effectiveness and gentle chemistry route resulting in the ultra-fine and homogeneous powder. The ability to obtain single-phase ferrite nano-sized magnetic nanostructure with controllable particle size and size distribution will improve its adequacy in a wide range of potential and technological applications. This synthesis method can produce fine, high-purity, stoichiometric particles of single and multi-component metal oxides. The aim of this work is to create and study the nanoparticles of the NiCrxFe2-xO4 systems, using sol-gel technology with the participation of auto-combustion (SGA). After completing the auto-combustion process, only one phase which corresponds to the cubic structure of the spinel space group Fd3m was obtained. The results of the study of the dielectric properties of nickel-chromium ferrites are shown in the temperature range of 298-723 K in the frequency range of 10-2-106 Hz. With an increasing frequency the real ϵ′ and imaginary ϵʺ components of the dielectric permeability decreases through contribution to the polarization processes at grain boundaries. It is shown that with the increasing temperature the conductivity of NiCrxFe2-xO4 ferrites also increases. It is found that at low temperatures the Verwey jump conductivity mechanism is dominant and in high temperature range the conductivity is described by the band model.