Molecular Dynamics Simulation On The Mechanical Properties Of H-BNC Two Dimensional Material

Graphene is a two-dimensional honeycomb material composed of carbon atoms,which shows excellent thermodynamic properties,mechanical properties,electrical and electronic properties.Ever since its discovery in 2004,a large group of scholars and researchers have conducted extensive research on it.So far,great progress has been made in the research on graphene,which now has become an exciting and booming area in nanomaterials.In the future,graphene is expected to find a broad range of applications in nano electronic devices,composite materials,sensor devices and semiconductor materials.In recent years,to further improve or tailor the properties of graphene,hexagonal boron nitride(h-BN)has been used to dope graphene and form a novel two dimensional composite material.In fabricating the material,carbon atoms in graphene are replaced by nitrogen atoms and boron atoms.,Due to the similar atomic radius of nitrogen atom.the C-C bond in graphene can be easily replaced by B-N bond and new C-B and C-N bonds will also be formed between carbon atoms(C),boron atoms(B)and nitrogen atoms(N).These transformations will lead to novel properties very different from those of pristine graphene.The sophisticated fabrication technique of the 2dimensional composite has been achieved which enables us to keep the doping ratio and doping shape of nitrogen and boron atoms in graphene under control.In this project,molecular dynamics simulation has been performed to study the effects of the concentration(?)and size(L)of nitrogen and boron atoms on the tensile,shear properties and fracture behavior of the doped graphene,The research work conducted is shown as follows:(1)By controlling the doping concentration of B and N atoms(?:0%-40%)and doping size(L:0.246nm-1.23nm),the tensile properties of the materials were explored and the two-dimensional nonlinear elastic constitutive relation has been established.The results show that the equivalent modulus of elasticity((4₀))of the new material decreases almost linearly with the increase of doping rate of B and N atoms(?).At the same time,due to the dependence of Y_e and,the effect of C-B bond of the fracture strain,the fracture strain decreases with the increase of?.In addition,the fracture mechanism of two-dimensional composites is discussed,and the effect of free boundary condition is studied.The results show that the free boundary condition can significantly reduce the elastic modulus((4₀))and fracture stress,but significantly improve the fracture toughness.(2)Changing the concentration of B and N atoms(?:0%-40%)and doping size(L:0.246nm-1.23nm),we have investigated the shear properties of the materials.Firstly,we have compared AIREBO potential and Tersoff potential,and examined their suitability for the simulation of graphene subjected to shear load.Our simulation results show that increasing the doping ratio?and doping size L of triangular h-BN atoms can reduce the shear fracture stress,but the shear modulus only decreases with the increase of doping ratio?.We also find that the bond breaking occurs first for C-B bond,which indicates that C-B bond in h-BNC material is the weakest link.Therefore,the increase of C-B bond number leads to the decrease of shear fracture stress..In addition,it is noted that the wrinkle height a and A/?of h-BNC decrease with the increase of doping ratio of B and N atoms,and the deformation ability of h-BNC decreases with the increase of temperature.