Preparation and magnetic properties of single phase Ni2Si by reverse Rochow reaction

Abstract

Single phase Ni2Si nanoparticles (NPs) have been successfully synthesized by using the Rochow reverse reaction, in which organosilanes ((CH3)nSiCl4−n) are used as the silicon source. The results demonstrate that the crystalline size and phase of nickel silicide can be controlled through changing the organosilanes and reaction time. A formation mechanism of Ni2Si NPs has been proposed, which involved reaction deposition and subsequently diffusion of Si atoms. Magnetism performance tests indicate that the saturation magnetization and coercive field of Ni2Si NPs depend greatly on the environmental temperature and particle size. The blocking temperature (TB) of the materials was found to strongly depend on selecting the organosilanes precursor: in the case of the Ni2Si-0 (148 K) and Ni2Si-2 (336 K). This novel methodology opens a route to prepare other classes of metal silicides with single phase and stoichiometry. The as-prepared single phase Ni2Si nanoparticles can find applications in ferrofluids, imaging, and magnetic separation due to its special magnetic behavior depending on the applied temperature (below or above TB).