Synthesis of Ni0.5Co0.5Fe2O4 ferrite and effect of annealing temperature on the structural, morphological and dielectric analysis.

Abstract

In the last decade, research on the synthesis and characterization of nanosized ferrites have highly increased, and a wide range of new applications for these materials have been identified. The ability to tailor the structure, chemical, optical, magnetic, and electrical properties of ferrites, by selecting the synthesis parameters further enhanced their widespread potential technological applications. Ferrites having their specialized characteristics like low electrical properties and losses etc, variation at low to high frequencies creates distinguished industrial employment with advanced technology[1].The nano-ferrites being confined to microwave device applications (phase shifters, circulators, isolators) due to their considerable low electrical conductivity and dielectric losses at gigahertz frequency range [2,3], has now become challenging as well as trending task to control the electrical conductivity at high frequencies. But nevertheless, the efforts have been going on to achieve the required properties, based on desired applications.

Among various ferrites, CoFe₂O₄, MnFe₂O₄, ZnFe₂O₄, NiFe₂O₄, and CuFe₂O₄ have attracted considerable attention due to numerous applications, as mentioned above. CoFe₂O₄ and NiFe₂O₄ grow in spinel-type crystal structures, which can be represented by (Fe³⁺) [Co²⁺Fe³⁺] O₄ and (Fe³⁺) [Ni²⁺Fe³⁺]O₄, respectively[4]. Recently, nanoparticles of Cobalt ferrites (CF)-based materials have gained remarkable interest due to their important conducting and insulating properties. Due to higher values of magnetostriction cobalt ferrites can be used for strain sensor and actuator applications [5]. Similarly, cobalt ferrite, nickel ferrite is also one of the suitable candidates for applications in the family of spinel ferrite. Nickel ferrite possesses high electrical resistivity, high saturation magnetization, high Curie temperature, low eddy current and dielectric losses [6,7]. The investigation of the reports suggests that, mixed ferrite possesses better properties and stability depending on the stoichiometry and nature of cations in the final compositions. Electrical and dielectric properties, along with magnetic properties of nanocrystalline mixed Ni-Co ferrites have been reported in the literature survey [8-10]. Gangatharan Sathishkumar, et al. [11] investigated the structural and dielectric properties of nano-particles of Co_(0.5-x)Ni_xZn_0.5Fe₂O₄ (x=0 to 0.3) prepared by co-precipitation method. Mangala U. Sawal, et.al [12] proposed research work which manifests the comparison of nanosized ‘as prepared’ Ni_0.5Co_0.5Fe₂O₄ ferrite with their ‘sintered’ counterpart concerning their effect on the structural and magnetic properties.

Likewise, various researchers have reported their work on the specific stoichiometric Ni_0.5Co_0.5Fe₂O₄ nanoparticles using various dry and wet chemical synthesis methods, along with the temperature variation concerning for various sintered samples. But, reports on the fabrication of stoichiometric Ni_0.5Co_0.5Fe₂O₄ NPs in pure spinel phase system, along with the effect of high annealing temperature on the structural, morphological and dielectric properties have been scarce in the literature.

The present study revolves around the main objective to synthesize Ni_0.5Co_0.5Fe₂O₄ ferrite via combining the sol-gel auto-combustion methods that results in a simple and inexpensive preparation method for high purity, homogenous nano powders. The nanoparticles were further sintered at three different temperatures (850^oC, 1050^oC, 1150^oC). Ferrite as single-phase system was obtained at temperature above 1000^oC. The fundamental aim of the work is to obtain different size of NPs and study their effect, on the dielectric properties for the storage device applications. On the contrary, there is also considerable interest in understanding new materials where effect of magnetic field on dielectric properties have gained rich flavour of physics for materials, such as Magneto-dielectrics. The NPs were further characterized using XRD, FTIR, XPS, FESEM, EDX, and IS impedance spectroscopy, was performed for investigating the structural, morphological, and dielectric properties of the ferrite nanoparticles.