Texture, nanotexture, and structure of carbon nanotube-supported carbon cones

International audienceGraphene-based carbon micro-/nano-cones were prepared by depositing pyrolytic carbon onto individual carbon nanotubes as supports using a specific chemical vapor deposition process. They were investigated by means of high-resolution scanning electron microscopy, lowvoltage aberration-corrected transmission electron microscopy, Raman spectroscopy, and molecular dynamics modelling. While the graphenes were confirmed to be perfect, the cone texture was determined to be preferably scroll-like, with the scroll turns being parallel to the cone axis. Correspondingly, many of the concentrically-displayed graphenes (actually scroll turns) exhibit the same helicity vector. When radii of curvature are large enough, this could allow for coherent stacking to locally take place in spite of the lattice shift induced by the curvature when radii of curvature are large enough. The graphene nanotexture was found to be perfect. A particular care was taken on investigating the cone apices, in which a specific type of graphene termination was observed, here designated as "zip" defect. Calculations determined a plausible stable structure that such a defect type may correspond to. This defect was found to generate the lowest Raman ID/ID' band ratio (1.5) ever found reported in the literature, for which physical reasons are proposed. Combining our results and that of the literature allowed proposing an identification chart for a variety of defects able to affect the graphene lattice or edges