Controlled synthesis and magnetic properties of nickel phosphide and bimetallic iron-nickel phosphide nanorods

Abstract

Nickel phosphide (Ni2P) and bimetallic iron-nickel phosphides [(FexNiy)(2)P] nanorods were fabricated by a seeded growth strategy. This strategy utilized pre-synthesized Fe3O4 nanoparticles as seeds and the thermal decomposition of metal precursors by multiple injections in a solution containing trioctylphosphine and didodecyldimethylammonium bromide (DDAB). The nanorods were characterized by transmission electron microscopy, X-ray diffraction, and magnetic measurements were carried out using superconducting quantum interference device (SQUID). The rod length was tunable, ranging from 10 to 110 nm depending on the number of injections, whereas the diameter of the rods was nearly 6 nm. It was found that the rod size increased with the number of injections under the constant total injection concentration and reaction time. In addition, the effect of the DDAB quantity used as a co-surfactant was studied, which showed that an optimum quantity was required to achieve uniform nanorods. Magnetic characterizations were performed over the two kinds of nanorods to identify their respective magnetic phases. The results demonstrated that the Ni2P nanorods were defined as a Curie-Weiss paramagnet, whereas the (FexNiy)(2)Pnanorods exhibited superparamagnetic characteristics.