Nano-particle Deposition in Porous and on Planar Substrates

Metal nanoparticles are formed via thermal evaporation in a controlled gas environment consisting of water vapor, argon, and hydrogen at temperatures near the melting point of the metal source. The metal source and substrate are contained within a dense alumina tube maintained at a desired pressure, sealed from outside gases, and heated by a tube furnace. The concentration of the metal in the gas phase can be increased by increasing the water vapor content and or lowering the total pressure. Continuous flow of the gas transports metal vapor to colder regions where the substrate is placed. Metal deposition from the supersaturated vapor occurs on or within the substrate due to this temperature gradient. Infiltration of the vapor phase and subsequent deposition within the porous substrate can be enhanced by lowering the total pressure (<1 atmosphere) in the system; lower total pressures, increases the diffusivity of the vapor species within the porous substrate. Misty Farrell mfpenn@bu.edu 617-358-3795