Effect of zirconium doping in the microstructure, magnetic and dielectric properties of cobalt ferrite nanoparticles

Zirconium doped cobalt ferrite nanoparticles (Co1-xZrxFe2O4 where x = 0, 0.25, 0.50, 0.75 and 1) have been successfully engineered via co-precipitation method. X-ray diffraction studies reveal single phase cubic spinel structures up to Zr content of 50% with average sizes in the range of 16-26 nm.Particle sizes decrease with Zr doping due to increased strain in the crystal lattice. Fourier Transform Infrared and Raman spectra reveal the formation of mixed spinel ferrite particles. Presence of cobalt, zirconium, iron and oxygen in the prepared nanoparticles were identified by X-ray fluorescence analysis. Morphology of the samples investigated by Transmission Electron Microscopy shows the formation of nearly spherical particles. The surface characteristics identified by X-ray photoelectron spectroscopy confirms the substitution of zirconium ions mainly into octahedral sites with partially inversespinel structure. Thermal stability studies proves that ferrite formation to be a continuous process. Electrical properties such as dc resistivity as a function of temperature and ac conductivity with frequency were studied for all samples. The variation of dielectric properties like dielectric constant and dielectric loss are also studied as a function of frequency and these results reveal that the dispersion is due to interfacial polarization and hopping of charge carriers. Saturation magnetization, remanence and coercivity values changes with Zr substitution. The high coercive field obtained for Zr doped samples reveals their ferromagnetic nature suggesting a wide range of applications in telecommunication, data processing, consumer electronics, aerospace, catalysis and bio surgical applications. (C) 2019 Elsevier B.V. All rights reserved.