Colloidal synthesis of indium nanoparticles by sodium reduction method

Nanocrystalline indium particles are prepared by direct reaction of sodium metal with anhydrous indium trichloride in N,N′-dimethylformamide (In-1) or n-trioctylphosphine (In-2 and In-3) as a solvent at a temperature between 120 and 360 °C under the atmosphere of argon. The product was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible spectroscopy and thermogravimetric analysis (TGA). XRD patterns of In-1 exhibit broad peaks with particle diameter of about 15 nm while In-2 and In-3 particles have bigger particle size of about 50 nm reflecting the effect of solvents and reaction temperatures. Absorption spectroscopy measurements reveal the solvent dependence of surface plasmon resonance with the sharp absorption peaks at about 290 nm for In-1 in toluene and 260 nm for In-3 in dichloromethane.