Nanostructured Materials

   Recently, we have developed a new method for generating nanoscale metal oxide, nitride or carbide particles down to 5 nm size by laser vaporization of metal targets followed by gas phase reactions and deposition onto cold surfaces in a diffusion cloud chamber. Particle size is readily controlled by the degree of supersaturation, which is controlled through the temperature gradient, pressure and laser power. The composition is controlled by the choice of the solid target and the gas mixture.

   Using this method, we have discovered a new form of silica nanoparticles that aggregate into a novel weblike microstructure with ultra high porosity and a very large surface area (500 m^2/g) and exhibit bright blue photoluminescence [C&E News, January 15, 1996]. This material can provide new applications in optical devices, catalyst support and as a polymer reinforcing agent.