Graphene is the most required engineering material in the twenty first century, largely due to its exceptional mechanical, thermal and electrical properties. For Example monolayer of graphene sheet has Young’s modulus of about 1 TPa [Ref], shear modulus of 280 GPa [Ref], fracture strength of 130 GPa [Ref], thermal conductivity of 5000 W/mK [Ref], longitudinal sound velocity of 20Km/s [Ref], melting temperature of 4900 K [Ref] and also it has high electron mobility of 250,000 cm2/Vs [Ref] at room temperature. All these exceptional properties can be attributed due its 2D (two dimensional) honeycomb lattice of sp2-hybridized carbon atoms as shown in [Fig 1]. Due to the above said properties it has attracted increasing research …show more content…
Two dimensional (2D) crystals such as graphene and hexagonal boron nitride have been considered only recently. Imperfection in graphene can be due to different methods of production, chemical treatment and irradiation [Ref]. It is always known that defects are not stationary and that their migration can have an important influence on the properties of a defective crystal [Ref]. In graphene, each defect has certain mobility parallel to the graphene plane [Ref]. The mobility may be immeasurably low, for example, for extended vacancy complexes, or very high, for example, for adatoms on an unperturbed graphene lattice [Ref].
Defects can be classified by their extent as zero, one, or two dimensional defects. One of the unique properties of the graphene lattice is its ability to reconstruct by forming nonhexagonal rings. For example Stone-Wales (SW) defect (surface defects) [Ref], which does not involve any removed or added atoms. The Stone-Wales defect is the 90° rotation of two carbon atoms with respect to the midpoint of the bond. In Stone-Wales defect, four hexagons are changed into two pentagons and two heptagons. The pentagons are separated by heptagons (Fig 2). The number of atoms (vertexes) does not