Carbon films with an<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>sp</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>network structure

Alexandrou, I.; Scheibe, H.‐J.; Kiely, Christopher J.; Papworth, A. J.; Amaratunga, G.A.J.; Schultrich, B.

doi:10.1103/physrevb.60.10903

Cited by 158 publications

(102 citation statements)

References 19 publications

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“…Moreover, the hardness estimated in this work is of the same magnitude as the experimental hardness reported by Alexandrou et al for carbon films with a sp 2 network structure. 27 Furthermore, our estimated hardness is in very good agreement with that reported by Brazhkin et al for polymerized fullerites of a similar density. 9 Our theoretical results, on the other hand, by no means supports the hypothesis that the orthorhombic structure proposed by Chernozatonskii et al 6 could account for the extremely high hardness and elastic moduli reported for samples of fullerene C 60 quenched from 13 GPa and 820 K. In fact, the reported hardness may be overestimated by the lack of an adequate treatment of the possible effect of elastic recovery on the experimental measurements.…”

Section: Resultssupporting

confidence: 81%

“…High hardness ͑45 GPa͒ and elastic recovery ͑85%͒ has been reported for sp 2 -rich carbon films. 27 In that case, the high degree of elastic recovery is accompanied by a very small overall indentation depth, as should be expected for an elastic but hard material. To our knowledge, the actual amount of elastic recovery in indentation tests performed with sp 2 -rich polymerized fullerites have not been reported.…”

Section: Resultsmentioning

confidence: 83%

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First-principles calculation of the structure and elastic properties of a 3D-polymerized fullerite

Perottoni

Jornada

2002

Phys. Rev. B

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In this paper we present results obtained from first-principles calculations concerning the crystal structure and elastic properties of a three-dimensional-polymerized fullerite. The orthorhombic structure we studied was first proposed on the basis of an x-ray-diffraction analysis of samples quenched from high-pressure and high-temperature conditions. The single-crystal bulk modulus for the optimized structure is 302 GPa, and Hill's average shear modulus for the polycrystalline aggregate is 301 GPa. Our results indicate that this orthorhombic fullerite should be hard, but not harder than diamond ͑a Knoop hardness of about 30 GPa͒, with a fracture toughness probably higher than that for diamond.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 83%

First-principles calculation of the structure and elastic properties of a 3D-polymerized fullerite

Perottoni

Jornada

2002

Phys. Rev. B

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“…Warped layers, with curved regions which are reminiscent of the spherical fullerenes, have been observed. 37 These structures seem similar to proposed models of negatively curved graphene layers. 38 Theoretically, these compounds ͑schwarz-ites͒ are supposed to be very stable and contain a macroscopic fraction of heptagonal rings.…”

Section: Expected Sources Of Disorder In Graphene Sheetssupporting

confidence: 61%

Electron-electron interactions in graphene sheets

2001

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The effects of the electron-electron interactions in a graphene layer are investigated. It is shown that short-range couplings are irrelevant and scale towards zero at low energies, due to the vanishing of density of states at the Fermi level. Topological disorder enhances the density of states and can lead to instabilities. In the presence of sufficiently strong repulsive interactions, p-wave superconductivity can emerge.

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“…In pure carbon films, sets of curved graphite sheets were observed (Alexandrou et al, 1999), which are explained by the presence of nonhexagonal (pentagonal, heptagonal) rings in the graphitic planes Brabec et al, 1995;Robertson et al, 1992). The incorporation of nitrogen promotes the pentagon formation; therefore, it promotes the curving of the planes (Czigá ny et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…The graphene layers can be easily displaced and bent; further, they can form fullerene-like structures with curved or closed lamellae systems . The nonhexagonal rings present in the sheets are responsible for curving of the layers and for the formation of a pseudo-3D graphitic structure by interlinking of the curved segments (Alexandrou et al, 1999;Ugarte, 1992). In the presence of nitrogen, fullerenelike carbon nitride films form (Sjöström et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Growth model for arc-deposited fullerene-like CNx nanoparticles

Veisz

Radnóczi

2005

Microsc. Res. Tech.

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Multiwall CN x nanotubes, nanoonions, and amorphous nanoballs were formed by carbon DC arc evaporation in a nitrogen atmosphere. The samples were investigated by conventional and high-resolution transmission electron microscopy. We propose a fragment-by-fragment growth mechanism for the formation of the nanoparticles. Accordingly, particles and aggregates of particles form in the vacuum ambient by the collisions between atomic species and small fragments. This growth model is supported by the discontinuous inner shells and disordered surface layers composed from graphene fragments. Image simulations confirm the detectability of dangling and back-folding surface layers in the experimental images. Further, the simulated images also confirm that the growth of nanoonions starts from a single fullerene-like seed. The amorphous nanoballs form when ordering of the building blocks during growth is hindered by the cross-linking nitrogen bonds. Microsc. Res. Tech. 67:100-105, 2005. V

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Carbon films with ansp2network structure

Cited by 158 publications

References 19 publications

First-principles calculation of the structure and elastic properties of a 3D-polymerized fullerite

First-principles calculation of the structure and elastic properties of a 3D-polymerized fullerite

Electron-electron interactions in graphene sheets

Growth model for arc-deposited fullerene-like CNx nanoparticles

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