Yuan Jianhui, Liew K M
School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410004, China
J Nanosci Nanotechnol. 2012 Mar;12(3):2617-24. doi: 10.1166/jnn.2012.5802.
The structural performance of graphene and boron-nitride nanosheet (BNNS) with zigzag and armchair types, when subjected to high temperatures, is investigated through molecular dynamics simulations. It is found that the degree of structure distortion is related to chirality; materials at high temperature of 3500 K, the zigzag nanosheet always exhibits less distortion than the armchair for the same material, and the BNNS exhibits less distortion than graphene for the same chirality. Graphene and BNNS with different in-plane compressive strains are optimized by using the Universal Force Field (UFF) method. It is found that there are two entirely different buckling modes, i.e., the lateral buckling of graphene begins to occur at the middle part, whereas buckling of BNNS begins to occur at near both ends and shows lateral deformation in two opposite directions. The coefficient of elasticity of graphene is slightly smaller than that of BNNS for the same chirality, the coefficient of elasticity of zigzag is slightly bigger than that of armchair for the same material, buckling strain of zigzag nanosheet is larger than that of armchair for the same material, and buckling strains of graphene are always larger than those of BNNS. These phenomena are also analyzed on the basis of radial distribution function (RDF) and system energy. The results indicate that there are thermal expansion anisotropy and planar stress anisotropy in a graphene and a BNNS. Among these materials, zigzag graphene has the highest resistance to compressive buckling but zigzag BNNS can have the highest resistance to distortion at high-temperature distortion and have high compression elasticity.
通过分子动力学模拟研究了锯齿形和扶手椅形的石墨烯和氮化硼纳米片（BNNS）在高温下的结构性能。发现结构畸变程度与手性有关；在3500 K的高温下，对于相同的材料，锯齿形纳米片的畸变总是比扶手椅形的小，对于相同的手性，BNNS的畸变比石墨烯的小。使用通用力场（UFF）方法对具有不同面内压缩应变的石墨烯和BNNS进行了优化。发现存在两种完全不同的屈曲模式，即石墨烯的横向屈曲开始于中部，而BNNS的屈曲开始于两端附近，并在两个相反方向上表现出横向变形。对于相同的手性，石墨烯的弹性系数略小于BNNS，对于相同的材料，锯齿形的弹性系数略大于扶手椅形，对于相同的材料，锯齿形纳米片的屈曲应变大于扶手椅形，并且石墨烯的屈曲应变总是大于BNNS的屈曲应变。还基于径向分布函数（RDF）和系统能量对这些现象进行了分析。结果表明，石墨烯和BNNS中存在热膨胀各向异性和平面应力各向异性。在这些材料中，锯齿形石墨烯具有最高的抗压缩屈曲能力，但锯齿形BNNS在高温畸变时可能具有最高的抗畸变能力并具有高压缩弹性。
