Size- and structure-controlled synthesis and characterization of nickel nanoparticles.

Nearly monodisperse face-centered cubic (fcc) and hexagonal close-packed (hcp) nickel nanoparticles have been prepared via the thermal decomposition of nickel organometallic precursors in a reaction mixture containing alkylamine, and characterized by powder X-ray diffraction, transmission electron microscopy and magnetic measurement. The employed alkylamine can serve as both solvent and reducing agent. The as-synthesized nickel nanoparticles are air-stable, and their sizes can be readily tuned by the variation of surfactant concentration and reaction temperature. The crystalline phase control was achieved by adjusting alkylamine concentration, heating rate and reaction temperature. Magnetic measurements showed that hcp Ni nanoparticles have quite different magnetic properties compared to fcc Ni nanoparticles.