RESEARCH INTERESTS

Uses solid-state synthesis, x-ray and neutron scattering, electrical and thermal transport, and other techniques to prepare and study novel nanostructured materials, mostly carbon nanotubes and semiconductor nanowires. Performs experiments directed towards fundamental understanding of structure-property relations and potential applications.

CURRENT RESEARCH PROJECTS

CARBON NANOTUBES can be envisioned as single hexagonal graphite layers rolled into long, seamless cylinders a few nanometers in diameter and many microns long. Believed to be atomically perfect, these exhibit spectacular mechanical and electrical properties. As part of a large interdisciplinary team, we are studying the fundamental properties and potential applications of this new class of materials. Examples of the latter include tiny analogs of field effect transistors (the "tubeFET"), electrochemical devices for energy storage, high-strength light weight composites and hydrogen storage.

SEMICONDUCTOR NANOWIRES exhibit electrical and optical behavior which is determined by the nanoscale diameter and are therefore tuneable. We synthesize nanowires of various elemental, compound and alloy semiconductors and study their electrical and electro-optical properties. Examples include Si, GaN, and large band-gap oxides.

Short introduction to Si nanowire device (by Kumhyo Byon)

EXTERNAL COLLABORATIONS

R. E. Smalley, M. Pasquali et al. (Rice University): dispersion of nanotubes in strong acids; synthesis and properties of partially oriented multifunctional spun fibers; structure and transport properties. Office of Naval Research/DURINT: N00014-01-1-0657 09/01/2004 - 08/30/2006

Y. Gogotsi (Drexel University) and T. Yildirim (NIST): carbide-derived carbons with controlled porosity, optimized for hydrogen storage; synthesis, structure, sorption and desorption energetics and kinetics, inelastic neutron scattering and neutron prompt gamma activation analysis; modeling and theory. Department of Energy DE-FC36-04GO14280, 09/01/2004 – 08/30/2007

Peter Eklund (Penn State University): synthesis, properties and applications of inorganic semiconductor nanowires. National Science Foundation/NIRT: DMR-0304178, 08/01/03 – 07/31/06.

Philippe Poulin, Alain Penicaud (Centre de Recherche Paul Pascal, Bordeaux): structure-property correlations in SWNT fibers spun from PVA/water suspension, dispersion of nanotube salts in polar solvents; x-ray, Raman and transport studies; small-angle neutron scattering.