Electrical and Magnetic Properties of Nickel - Cobalt Nano - Ferrite

Abstract

This work presents the effect of preparation method on structural, magnetic and electrical properties of NixCo1-xFe2O4 nanoferrite with x=0, 0.25, 0.5, 0.75 and 1. “Sol gel” was the first method used to synthesize nanospheres Ni-Co ferrites with citric acid as a fuel and assigned as “Nanospheres”, while “Hydrothermal” was the second method used to synthesize nanorods Ni-Co ferrites with oxalic acid as a fuel and assigned as “Nanorods”. Structural characterization for Ni-Co nanoferrites was carried out by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-ray analysis (EDX). Magnetic parameters were determined from Vibrating Sample Magnetometer (VSM) for both series and it was noticed that both Hc and Mr have lower values in nanospheres than nanorods. Curie temperature showed a gradual decrease for nanospheres, while nanorods showed an enhancement for Curie temperature with increasing Ni-content. Temperature dependence of both DC electrical resistivity and thermoelectric power are carried out for both series in the temperature range 385-548 K. Nanospheres showed higher values for resistivity and thermoelectric power coefficient than nanorods. The cation distribution was proposed for both series such that it verifies the lattice parameter and magnetization of each composition as well as the behavior of resistivity and thermoelectric power. It was found that the two series have two different cation distribution. All these changes are strongly attributed to the change in particle shape. Finally, the conduction mechanism was deduced for both series.