Size and morphology-controlled synthesis of Ni3C nanoparticles in a TEG solution and their magnetic properties†
Abstract
Nickel carbide nanoparticles (Ni3C NPs) were synthesized by a polyol solution refluxing route at a temperature of 300 °C for 20 min using triphenylphosphine oxide (TPPO) as the surfactant. Size and morphologies of the Ni3C NPs were controlled by adjusting the concentration of Ni(NO3)2 and TPPO. The products consisted of Ni and Ni3C could be kinetically controlled by a reaction temperature of 250–290 °C and time less than 20 min and the proportion of the Ni component was lower with longer reaction times and higher temperatures due to carbon atom insertion via a carbonaceous film that formed on the surface of the growing particles. The formation process of the Ni3C NPs was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS) characterization. The saturation magnetizations of products decreased with decreasing ratio of Ni : Ni3C, which inferred that Ni3C was non-magnetic and the magnetism arose from trace Ni in the products.