Perfection in carbon nanotechnology - the zoo of defects from first principles
Malcolm I Heggie, R. H. Telling, C. P. Ewels, A. El-Barbary, S. Scarle and C. Dean
University of Sussex, UK
Keywords: defects, dislocations, graphite, nanotubes, modeling, first principles, vacancy, interstitial, dislocation, disclination
Nanotubes and graphite have fantastic properties, but pose severe experimental problems in their growth and assessment. The extreme conditions required by their growth such as electric arc, plasma or pyrolysis are only amenable to coarse control and monitoring. The short C„ŸC bond length and delocalised ƒÎ orbitals push the interpretation of electron microscopy and scanning microscopies to their limits.
First principles techniques, which give the energy landscape for the atomic structures of carbon allotropes, have been crucial in our understanding of measured and predicted properties of carbon nanotubes. Here we describe their application to defects within graphite-based materials, which are important in determining many of the properties in real carbon systems, just as they are in, for example, standard semiconductors.
The defect zoo comprises vacancy, interstitial, dislocation and disclination related defects that control most of the measurable properties of sp2 based carbon systems. Density functional calculations reveal a richness in the structures and behaviour of these defects which is almost unparalleled in any other material and provides a first principles explanation of lubrication, turbostratic disorder, stored energy and the perfection of nanotubes.
NSTI Nanotech 2003 Conference Technical Program Abstract