Conical crystals of graphite

Carbon nanocones: wall structure and morphology

“…The strain at the cone apex will eventually result in n pentagons near the apex and in the nominal cone apex angles of α = 2 arcsin [(6 − n) /6] [18,19]. Note that these particles are fundamentally different from carbon nanohorns [20], naturally occurring scrolled conical carbon structures [21], as well as the multi-shell graphitic cones such as those investigated by Gogotsi et al [6,7]. The latter are long needle-shaped structures where the diameter is nearly constant over the length of the particle.…”

“…More recently, other intriguing non-planar carbon morphologies have appeared, both occurring naturally and produced synthetically [4]- [10]. Beautiful examples are the different forms of polyhedral graphite crystals as those studied by Gogotsi et al [6,7]. The various ways that carbon atoms may organize with respect to each other, can conveniently be rationalized via proper combination of sp 3 , sp 2 and sp 1 orbitals, as illustrated by Inagaki [11] and Dimovski [12].…”

Fourier Transforms of Tubular Objects with Spiral Structures

“…Later studies generated nanometer-sized carbon cones by vapor condensation of carbon atoms on a graphite substrate [10], while others reported generation of carbon structures consisting of graphitic microstructures with total disinclinations that are multiples of +60˚, due to the presence of pentagons within the hexagonal structure, resulting in the formation of carbon cones [11], or horn-shaped sheaths of single walled graphene sheets [12]. Graphite nano and microcones were found in the pores of commercial glassy carbon, growing along with cylindrical multiwalled nanotubes and graphite polyhedral crystals [14]. Tubular graphite cones synthesized using a chemical vapor deposition method were found to be composed of cylindrical graphite sheets; a continuous shortening of the graphite layers from the interior to the exterior makes them cone shaped [15].…”

“…However, later discovery of graphitic cones and boron nitride cones [10][11][12][13] showed that instead of parallel cylinders, there may occur coaxially rolled-up cylinders, as well as tapering cylinders, sometimes ending into sharp cones, sometimes into hollow tapering cylinders, and sometimes end ing into various angles. The various forms assumed by nanotubes include isolated cones [12], disordered aggregates of cones [10], multilayered cones with different apex angles [14,15], as well as stacked closed cones, also called stacked lampshades. Among naturally occurring minerals, Halloysite [16], Cylindrite [17], tochilinites [18] etc form cylindrical morphology.…”

Nucleation and growth studies of crystalline carbon phases at nanoscale.

“…There were called nanohorns. Graphite polyhedral crystals [124] and conical crystals [125] were discovered by fracturing the surface of glassy carbon.…”