Effect of Grain Boundaries’ Doping on the Mechanical Properties of Nitrogen-Doped Bicrystalline Graphene

Abstract

Grain boundaries and doping play an important role in influencing the mechanical behaviour of materials. In this article, Tersoff potential based molecular dynamics simulations were employed to comprehensively investigate the effect of random N doping on the mechanical behaviour of pristine and bicrystalline graphene nanosheets. For bicrystalline nanosheets, three types of grain boundaries with high, transition and low tilt angles, were considered here. Each grain boundary model was doped as a whole nanosheet, only grain boundary area, and/or non-grain boundary area. Our results show that the configurations with doping of grain boundary area showed more deterioration in failure stress and failure strain values than the configurations with doping of the non-grain boundary area. Also, N doped pristine nanosheets and the configurations with non-grain boundary area doping showed a monotonic increase in Young's modulus while a monotonic decreasing-increasing trend was predicted for the rest of the configurations. These results show that the doping of the grain boundary area is more detrimental to the mechanical properties than the doping of the non-grain boundary area. Moreover, even after N doping, the high angle grain boundaries show higher strength as compared to the low angle grain boundaries.