Showing papers on "Graphene published in 1993"
TL;DR: In this paper, the relationship between the phonon modes in carbon nanotubules and those in a graphene sheet is studied by use of the zonefolding method, and the modes identified with pure translations and rotations are identified.
368 citations
TL;DR: In this paper, the electronic structure of coaxial, graphene double-layer tubules is predicted for various combinations of metallic and insulating constituent inner and outer monolayers, depending on the diameter and chirality of the tubule.
Abstract: The electronic structure of coaxial, graphene double‐layer tubules is predicted for various combinations of metallic and insulating constituent inner and outer monolayers, depending on the diameter and chirality of the tubule. For the examples chosen, some of the energy bands of the inner and outer tubules are coupled to each other by commensurate interlayer interactions. Nevertheless, because of symmetry, the energy bands of metallic monolayer tubules remain metallic even after interlayer interactions are considered. The possible implications of these results on molecular metal‐insulator devices are discussed.
270 citations
TL;DR: In this paper, two commercially available ex-PAN carbon fibers, T-300 and Courtaulds-XAU, were studied by scanning tunneling microscopy, and the results at large scales have shown that the surface aspects of carbon fibers are mainly determined by the spinning procedure of precursor, rather than the precursor materials.
38 citations
TL;DR: In this paper, the structural and electronic properties of fluorine- and bromine-intercalated graphite fibers and HOPG are summarized, and a thermodynamic model is proposed that accounts for the differences between fluorine and other graphite materials.
Abstract: The structural and electronic properties of fluorine- and bromine-intercalated graphite fibers and HOPG are summarized. In contrast to the bromine intercalate, which is purely ionic for any experimentally attainable intercalate concentration, fluorine has a dual ionic and covalent behavior in graphite. Furthermore, whereas bromine-intercalated graphite is ordered, fluorine-intercalated graphite is disordered. The stiff graphene planes are buckled and islands of various fluorine concentrations are formed. A thermodynamic model is proposed that accounts for the differences between fluorine- and bromine-intercalated graphite materials. The model describes the competition between ionically bonded and covalently bonded intercalate phases of fluorine in graphite. Covalent bonding is more favorable energetically, but an important nucleation barrier exists due to strain and to the destruction of the conjugation of the double bonds.
29 citations
TL;DR: In this article, a high resolution transmission electron microscopy study of carbon soot particles produced in arc-discharge experiments is presented, which allows direct visualization of the atomic structures of the clusters.
Abstract: We present a high resolution transmission electron microscopy study of carbon soot particles produced in arc-discharge experiments. This technique allows direct visualization of the atomic structures of the clusters. Tubular and concentric-shelled graphitic structures are produced on the surface of contact between the electrodes. Strong electron bombardment of the carbon soot generates as a final result, concentric-shelled, graphitic particles, exhibiting a remarkable spherical shape.
5 citations