Magnetite nanoparticles with tunable gold or silver shell

Abstract

Fe₃O₄ nanoparticles with size ∼13 nm have been prepared successfully in aqueous micellar medium at ∼80° C. To make Fe₃O₄ nanoparticles resistant to surface poisoning a new route is developed for coating Fe₃O₄ nanoparticles with noble metals such as gold or silver as shell. The shell thickness of the core–shell particles becomes tunable through the adjustment of the ratio of the constituents. Thus, the route yields well-defined core–shell structures of size from 18 to 30 nm with varying proportion of Fe₃O₄ to the noble metal precursor salts. These magnetic nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), FTIR, differential scanning calorimetry (DSC), Raman and temperature-dependent magnetic studies.