Aerosol Synthesis of Metal and Metal Oxide, Nitride and Carbide Nanoparticles Using an Arc Evaporation Source

Nanoparticle synthesis by condensation from the vapor is a versatile process which allows control of both particle size and composition. We have developed a novel aerosol source for producing nanoparticles of metals and metal oxides, nitrides and carbides with controlled mean size. Metal is vaporized by heating a liquid metal pool by means of an atmospheric pressure d.c. arc. The evaporated atoms are entrained in a steady stream of inert gas and are quickly transferred to a quench region where the hot stream from the arc plasma is mixed with a second stream of cold gas. The role of the quench gas is to suppress aggregation by both rapid cooling and dilution. Metal oxide, nitride, and carbide particles are formed by the addition of oxygen, nitrogen, and methane respectively to the inert gas flow in either the arc or the quench region. The size of the primary particles is controlled by varying the metal atom density and residence time in the arc plasma and in the quench region. Cluster aggregation is controlled by varying the cluster density in the flow downstream from the quench region.