New preparation method and characterization of spheric silver nanoparticles

Colloidal silver nanoparticles were prepared by decomposing silver carbonate with hydrothermal method in the presence of polyvinyl pyrrolidone (PVP) as protecting agent and without any reducing agent, which were then centrifugally separated and dried to produce nanometer silver powder. Effects of the reaction conditions on the morphology and growth of silver nanoparticles were analyzed by variation of the reaction temperature, time, surfactant concentration, kind and the reagent concentration. Analysis with X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) indicates that the optimum preparation conditions include reaction temperature of 180°C, reaction time of 5 h, with 0.1 mol/L AgNO3, 0.05 mol/L NaHCO3, and 1.7 g PVP, under which the silver nanoparticles prepared are spherical in shape, narrow in size distribution with single dispersion and about 40 nm in particle size. It is thus concluded that concentrations of surfactant PVP, AgNO3, and NaHCO3 have significant impact on the synthesis of spheric silver nanoparticles.