MECHANICAL RELAXATION AND INTRAMOLECULAR PLASTICITY IN CARBON NANOTUBES

The question of how carbon nanotubes (CNT)-believed to be the stronges t filaments-relax under tension has been addressed. A dislocation theo ry applied to a two-dimensional nanocrystal such as the CNT describes the main routes of mechanical relaxation in this molecular structure: a brittle cleavage or, at high temperatures, a plastic flow. Both star t with diatomic rotation, which ''unlocks'' the pristine wall of CNT b y creating a dislocation dipole with the pentagon-heptagon cores. Unde r high stress, the dislocations depart from each other along helical p aths, leaving behind a nanotube of smaller diameter, well-defined new symmetry, and changed electrical properties. (C) 1998 American Institu te of Physics.