title: Imaging active topological defects in carbon nanotubes.
abstract: A single-walled carbon nanotube (SWNT) is a wrapped single graphene layer, and its plastic deformation should require active topological defects--non-hexagonal carbon rings that can migrate along the nanotube wall. Although in situ transmission electron microscopy (TEM) has been used to examine the deformation of SWNTs, these studies deal only with diameter changes and no atomistic mechanism has been elucidated experimentally. Theory predicts that some topological defects can form through the Stone-Wales transformation in SWNTs under tension at 2,000 K, and could act as a dislocation core. We demonstrate here, by means of high-resolution (HR)-TEM with atomic sensitivity, the first direct imaging of pentagon-heptagon pair defects found in an SWNT that was heated at 2,273 K. Moreover, our in situ HR-TEM observation reveals an accumulation of topological defects near the kink of a deformed nanotube. This result suggests that dislocation motions or active topological defects are indeed responsible for the plastic deformation of SWNTs.
authors.forename: Kazu
authors.initials: K
authors.lastname: Suenaga
authors.forename: Hideaki
authors.initials: H
authors.lastname: Wakabayashi
authors.forename: Masanori
authors.initials: M
authors.lastname: Koshino
authors.forename: Yuta
authors.initials: Y
authors.lastname: Sato
authors.forename: Koki
authors.initials: K
authors.lastname: Urita
authors.forename: Sumio
authors.initials: S
authors.lastname: Iijima
mesh_terms: D006358:Hot Temperature; D007089:Image Enhancement / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing / Q000379:methods*; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D037742:Nanotubes, Carbon