Pereira M L, da Cunha W F, de Sousa R T, Amvame Nze G D, Galvão D S, Ribeiro L A
Department of Electrical Engineering, University of Brasília 70919-970, Brazil.
Institute of Physics, University of Brasília, 70910-900, Brasília, Brazil.
Nanoscale. 2022 Feb 24;14(8):3200-3211. doi: 10.1039/d1nr07959j.
Recently, a new two-dimensional carbon allotrope named biphenylene network (BPN) was experimentally realized. The BPN structure consists of four-, six-, and eight-membered rings of sp-hybridized carbon atoms. In this work, we carried out fully-atomistic reactive (ReaxFF) molecular dynamics simulations to study the mechanical properties and fracture patterns of non-defective and defective (nanocracks) BPN. Results show that, under uniaxial tensile loading, BPN is converted into four distinct morphologies before fracture starts. This conversion process is dependent on the stretching direction. Some of the formed structures contain mainly eight-membered rings, which have different shapes in each morphology. In one of them, a graphitization process occurs before the complete fracture. Importantly, in the presence of nanocracks, no new morphologies are formed. BPN exhibits a distinct fracture process when contrasted to graphene. After the critical strain threshold, the graphene transitions from an elastic to a brittle regime, while BPN can exhibit different inelastic stages. These stages are associated with the appearance of new morphologies. However, BPN shares some of the exceptional graphene properties. BPN Young's modulus and melting point are comparable to graphene, about 1019.4 GPa and 4024 K, respectively.
最近，一种名为联苯网络（BPN）的新型二维碳同素异形体通过实验得以实现。BPN结构由sp杂化碳原子的四元环、六元环和八元环组成。在这项工作中，我们进行了全原子反应性（ReaxFF）分子动力学模拟，以研究无缺陷和有缺陷（纳米裂纹）的BPN的力学性能和断裂模式。结果表明，在单轴拉伸载荷下，BPN在开始断裂前会转变为四种不同的形态。这种转变过程取决于拉伸方向。一些形成的结构主要包含八元环，在每种形态下具有不同的形状。其中一种形态中，在完全断裂之前会发生石墨化过程。重要的是，在存在纳米裂纹的情况下，不会形成新的形态。与石墨烯相比，BPN呈现出独特的断裂过程。在临界应变阈值之后，石墨烯从弹性状态转变为脆性状态，而BPN可以呈现不同的非弹性阶段。这些阶段与新形态的出现有关。然而，BPN具有一些与石墨烯相同的优异性能。BPN的杨氏模量和熔点与石墨烯相当，分别约为1019.4 GPa和4024 K。
