STRUCTURAL AND DIELECTRIC EVOLUTION OF COBALT FERRITE NANOPARTICLES FOR MICROWAVE APPLICATIONS

In this paper, coprecipitation method was used in the synthesis of cobalt ferrite nano particles, while investigations were carried out to determine the effect of sintering temperature on the structural and dielectric properties of the prepared samples. The structural/morphological and dielectric properties of the products were determined by X-raydiffraction (XRD), transmission electron microscopy (TEM), and open ended coaxial probe (OECP). Results from analysis confirms that heat treatment influences the magnitude of dielectric constant and the structural evolution of the samples. TEM mages reveal that the samples surfaces exhibit well-defined crystalline nanoparticles of spherical shapes with small agglomeration at higher sintering temperature while the sizes of the particles increases with annealing temperature due to grain boundary growth. The magnitude of dielectric constant was influenced by interfacial polarization as well as iron hopping of Fe2+ to Fe3+ and Co2+ to Co3+ at B-sites. Sintering temperature also influenced the dielectric characteristics, and this is confirmed from the dielectric measurements at room temperature. Based on the result obtained for dielectric constant, these samples are suitable for small microwave shielding.