Synthesis and characterization of fine and monodisperse silver particles of uniform shape

Abstract

Fine silver particles of uniform size and shape have been synthesized from silver nitrate in hot ethylene glycol. Quasi-spheric and monodisperse silver particles are produced only when particle sintering is prevented during the growth step. For this purpose, a protective agent, namely, polyvinylpirrolidone (PVP), was added to the system. Particle size increases with increasing temperature and PVP/silver nitrate weight ratio. Heterogeneous nucleation of metallic silver with a critical concentration of in-situ formed platinum nuclei produces monosize particles that have a rod-like shape. This drastic change in particle shape indicates that under these conditions PVP also acts as a crystal habit modifier. The thickness of rod-like particles changes when different PVP/silver nitrate weight ratios are used. Electron microscopy and X-ray diffraction techniques were used for particle characterization. The synthesis of metallic particles in liquid polyols, which act as both solvent and reducing agent, is a useful method for producing highly pure, fine, and monodisperse particles of uniform shape.