Nanoengineering Defect Structures on Graphene

Abstract

We present a new way of nanoengineering graphene by using defect domains. These regions have ring structures that depart from the usual honeycomb lattice, though each carbon atom still has three nearest neighbors. A set of stable domain structures is identified by using density functional theory, including blisters, ridges, ribbons, and metacrystals. All such structures are made solely out of carbon; the smallest encompasses just 16 atoms. Blisters, ridges, and metacrystals rise up out of the sheet, while ribbons remain flat. In the vicinity of vacancies, the reaction barriers to formation are sufficiently low that such defects could be synthesized through the thermally activated restructuring of coalesced adatoms.

Modifying the electronic structure of semiconducting single-walled carbon nanotubes byAr+ion irradiation

“…The former defects representing two adjacent pentagons and two heptagons can be formed by the incomplete recombination of vacancy-adatom pairs, 72 while the latter appears when two isolated CAs form a dimer on the surface which is then incorporated in the atomic network at the expense of local increase in the diameter and formation of nonhexagonal rings. 71 SW defects are known to be able to appear thermodynamically in mechanically strained nanotubes, 73,74 so that one can expect that the recombination of SV-CA pairs should result in a higher number of SW defects if small mechanical strain is present in the nanotube.…”

Implantation and Atomic-Scale Investigation of Self-Interstitials in Graphene

“…The bonding sites of single carbon adatoms, [23][24][25] and stable configurations of fully sp 2 -coordinated interstitial dimers incorporated in the graphene lattice [15][16][17] (see 1 for the atomic structures) have been theoretically predicted. Experimental evidence of single carbon adatoms in the so-called bridge position (with the extra atom sitting on top of a C-C bond of graphene) has been presented.…”

“…The resulting structures and their electron irradiation induced dynamics are characterized by AC-HRTEM operated at 80 kV. All the three theoretically predicted self-interstitial dimer structures [15][16][17] are observed in the samples. Furthermore, larger aggregates of sp 2 -bonded extra atoms, as well as dislocation dipoles with the associated local density surplus are observed.…”

Enormous shrinkage of carbon nanotubes by supersonic stress and low-acceleration electron beam irradiation

“…While the linear alignment of the SW defects generated wrinkle ridges, 16 the relatively small curvature of the SWNT body had a small tolerance to the introduction of wrinkle ridges into its body because the transformation energy needed to introduce a large folding angle into the thin SWNT wall would be extremely large; much more than needed for the destruction of the honeycomb lattice. However, the van der Waals attraction helped to preserve the relative interspacing of the tubes from the destruction of the SWNT bundle structure.…”

“…10 It is well known that high energy electron irradiation induces a variety of structural changes in carbon nanotubes; perpendicularly incident electrons induce lateral ejection of carbon atoms; thus creating Stone-Wales (SW) defects on the honeycomb lattice. [11][12][13][14][15][16] The threshold energy needed to induce this so-called "knock-on mechanism" is about 86 keV, 11 and the propagation of the SW defect plays an essential role in many structural transformations, 13 because a heptagonheptagon combination cannot sustain the initial flat surface but instead generates a local curvature. Therefore, SW defects combined with local excitation of the carbon bond induces a variety of carbon nanostructures 11,[17][18][19][20][21] including the creation of fullerenes from carbon soot, 17 lattice destruction into amorphous carbon, 11,18 nanotube scissoring, 19 and the cross-linking of nanotubes and fullerenes.…”