Mechanical failure of zigzag graphene nanoribbons under tensile strain induced by edge reconstruction

Abstract

CitationCheng The structural and mechanical properties of graphene nanoribbons (GNRs) under uniaxial tensile strain are studied by density functional theory. The ideal strength of a zigzag GNR (120 GPa) is close to that of pristine graphene. However, for a GNR with both edges reconstructed to pentagon-heptagon pairs (from hexagon-hexagon pairs) it decreases to 94 GPa and the maximum tensile strain is reduced to 15%. Our results constitute a comprehensive picture of the edge structure effect on the mechanical properties of GNRs.

Long triple carbon chains formation by heat treatment of graphene nanoribbon: Molecular dynamics study with revised Brenner potential

“…Directions of reactions are indicated by arrows.First let us compare the energetic characteristics of local structures at the edge of narrow ZGNRs obtained here by the DFT calculations with similar data from literature. While formation of pentagon-heptagon pairs at the zigzag graphene edge has been actively investigated in recent years using ab initio methods[25,53,60,61,62,63], we are not aware of such studies for formation of chains at graphene edges. The barriers and energy changes for simultaneous and complete reconstruction of the zigzag edge[53,60,61] as well as formation of the first[25,62,63] and second[62] pentagon-heptagon pairs have been reported.…”

“…the supercell included only 4 hexagons along the GNR edge. In Ref 62,. the formation of the first pentagon-heptagon pair at the free edge was found to lead to the energy increase of 0.2 eV, while the formation of the second pair next to the previous one to the energy reduction of 0.7 eV.…”

Energetics of atomic scale structure changes in graphene

“…In particular, reconstruction of the zigzag (ZZ) edge via the transformation of pairs of adjacent hexagons to pentagon-heptagon pairs (Fig. 13a) is energetically favourable 77,96,148,164,[242][243][244][245][246][247][248]253 and is often observed experimentally. 13,75,254,255 This reconstruction (ZZ(57)) decreases the zigzag edge energy by 0.1-0.4 eV Å À1 , making it even slightly more stable than the armchair (AC) edge ( Table 6).…”

“…The calculation method (SP and NSP stand for ''spinpolarised'' and ''non-spin-polarised'' calculations, respectively) is indicated zigzag edge. 77,245,247,248 Activation energies of just 0.69 eV and 0.44 eV for each respective step were obtained, indicating that such a transformation should take place spontaneously at room temperature. 96 A similar free energy barrier of 0.83 eV was obtained at room temperature using a semiempirical potential.…”

“…The energetics of all atomic-scale reactions change upon approaching graphene edges, 52,56,[67][68][69][70][71] and this is especially important for graphene nanoribbons. Edge reconstructions with the formation of topological defects are frequently observed under electron irradiation 13,[72][73][74][75]270 and significantly deteriorate elastic 76 and fracture 77 properties of graphene nanoribbons. Creation of defects at the edges of graphene nanoribbons can also be used to tune electron [78][79][80][81][82][83][84][85] and thermal 86 transport.…”