The influence of tilt grain boundaries on the mechanical properties of bicrystalline graphene nanoribbons

Highlights: • Tilt GB models are constructed based on the theory of disclinations in crystals. • The mechanical properties of bicrystalline graphene nanoribbons are studied. • Several factors are proved to affect the ultimate strength and the Young's modulus. • The factors include the misorientation angle, chirality, defects distribution. • GB has influence on the size effects of graphene Young's modulus. The mechanical properties of bicrystalline graphene nanoribbons with various tilt grain boundaries (GBs) which typically consist of repeating pentagon–heptagon ring defects are investigated based on the method of molecular structural mechanics. The GB models are constructed via the theory of disclinations in crystals, and the elastic properties and ultimate strength of bicrystalline graphene nanoribbons are calculated under uniaxial tensile loads in perpendicular and parallel directions to grain boundaries. The dependence of mechanical properties is analyzed on the chirality and misorientation angles of graphene nanoribbons, and the experimental phenomena that Young's modulus and ultimate strength of bicrystalline graphene nanoribbons can either increase or decrease with the grain boundary angles are further verified and discussed. In addition, the influence of GB on the size effects of graphene Young's modulus is also analyzed.