Synthesis of Inorganic Nanoparticles via a Plasma/Gas-Phase Process

摘要

The Distributed Arc Cluster Source (DACS) is a gas phase reactor specifically designed for production of large quantities of nanoparticles having a controlled size and a controlled atomic composition. It provides a versatile platform for synthesis of unaggregated inorganic nanoparticles consisting of metal atoms, metal oxides, metal nitrides, and/or metal carbides. The particles are formed as bare particles in the gas phase. They are collected in the liquid phase as a colloidal suspension of molecularly protected particles by bubbling the aerosol stream containing the particles into a liquid solvent containing surfactant molecules which coat the particles and prevent them from aggregating. The DACS makes use of an atmospheric pressure DC arc to vaporize a liquid melt that can consist of a single atomic species or a mixture of atomic species. The vaporized atoms are entrained in an inert gas flow and are rapidly cooled. This results in the nucleation and growth of equiaxed solid particles. Although they are nearly spherical in shape, the particles often have non-equilibrium atomic structures because of the rapid cooling in the DACS. In some cases this can produce novel properties. If an equilibrium atomic structure is desired, it can often achieved either by thermally annealing the particles in the gas phase before they are collected or by thermally annealing the particles after they are collected. Selected examples of nanoparticles synthesized in the DACS are presented.