Dependence of the magnetic and optical properties of Ni-Co nanoferrite on the particle shape

This work presents the effect of particle shape on the magnetic and optical properties of Ni-Co nanoferrite (NCF). Two series of different preparation methods were used to obtain two different shapes of Ni_xCo_1-xFe₂O₄ where x=0, 0.25, 0.5, 0.75 and 1. Sol gel was the first method used to synthesize NCF with citric acid as a fuel and the second series was synthesized by hydrothermal route and the fuel was oxalic acid. Structural characterization for NCF nanomaterials was carried out by X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS) and Transmission Electron Microscope (TEM). Magnetic parameters were determined from Vibrating Sample Magnetometer (VSM) for all samples and it is noticed that the values of M_r and M_r/M_s are greater in nanorod series than nanosphere series. RLC Bridge was used to obtain the Curie temperature of the polycrystalline nanomaterials by the variation of relative permeability with increasing temperature. Values of direct and indirect band gaps were determined from double beam spectrometer using Diffused Reflectance Spectroscopy (DRS) measurements. It was found that changing particle shape could change the cation distribution, magnetic and optical properties of NCF nanoparticles. (paper)