ATOMISTIC MODELLING TO STUDY PROPERTIES OF GRAPHENE

Abstract

This thesis addressed that graphene is a regular monolayer of carbon atoms settled in a 2D- hexagonal lattice; that is listed among the strongest material ever measured with strength exceeding more than hundred times of steel. However the strength of graphene is critically influenced by temperature, vacancy defects (VD). Defects are at all believed to worsen the mechanical toughness and reduce the strength of graphene sheet. Revealed boldly that stiffness and strength are the key factors in determining solidity and life span of any technological devices; besides at the time of production defects can change the structural properties of any engineering material. A systematic MD simulation (MDs) study is performed in this thesis toward understanding the defects on the mechanical properties of graphene, that the MD simulations provide important comprehensions. Simulation of sheets with vacancy defects indicates that a single missing atom could diminish the strength by nearly 25%. Also MD based atomistic modeling was performed to predict and quantify the effect of non-bonded interactions on the failure morphology of vacancy affected sheets of graphene. Defective sheet of graphene containing VD was simulated in conjunction with the non-bonded interactions experienced due to the presence of pristine sheet of graphene. In this study, the author, revealed mechanical properties and failure morphology of bi-layer graphene sheets under the influence of single, double and multi-vacancy defects. It was concluded on the basis of atomistic simulations that non-bonded interactions as well as stiffness of pristine graphene sheet has significant impact on the failure morphology of the defective sheet of graphene. Non-bonded interactions in conjunction with defects can be further used for modifying the brittle nature of graphene to ductile.