Effect of heat treatment on structure and magnetic properties of FeCoNi/CNTs nanocomposites

Abstract

Fe46Co35Ni19/CNTs nanocomposites have been prepared by an easy two-step route including adsorption and heat treatment processes. We investigated the effect of heat treatment conditions on structure, morphology, nanoparticle sizes and magnetic properties of the Fe 46Co35Ni19 alloy nanoparticles attached on the carbon nanotubes by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), energy-disperse X-ray spectroscopy (EDS) and vibrating sample magnetometer (VSM). When the reducing temperature changes from 300-450°C, a transition of the crystalline structure from bcc phase to fcc-bcc dual phase and an increase in particle size of Fe46Co35Ni19 nanoparticles together with a local maximum at 350°C are observed. Meanwhile, the saturation magnetization (Ms) for Fe46Co 35Ni19 nanoparticles increases with the increase of reducing temperature and the coercivity (Hc) decreases rapidly with a local minimum at 350°C. When the reducing time (tr) changes from 2-5 h, bcc phase is predominant in the Fe46Co35Ni19 alloy particles. Both the particle size and Ms have a maximum at tr = 3 h, and the Hc reaches a maximum at tr = 4 h. © Indian Academy of Sciences.