Wang Shuaiwei, Yao Yin, Peng Zhilong, Zhang Bo, Chen Shaohua
Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and Structures, Beijing Institute of Technology, Beijing 100081, People's Republic of China.
Nanotechnology. 2021 Jul 23;32(41). doi: 10.1088/1361-6528/ac1220.
A new two-dimensional carbon-based material consisting of pentagonal and hexagonal elements is identified by numerical experiments, which is called phgraphene and possesses not only a tunable semimetallic feature but also a direction-dependent even sign-changed Poisson's ratio. The structural stability of such a new material is first checked systematically. It is found that phgraphene has a similar energy as the-graphyne, a thermally stable structure from the room temperature to 1500 K, and elastic constants satisfying the Born-Huang criterion. Both the band structure and density of states are further verified with different techniques, which demonstrate a Dirac semimetallic characteristic of phgraphene. A more interesting finding is that the band structure can be easily tuned by an external loading, resulting in the transition from semimetal to semiconductor or from type I to type III. As a new material that may be applied in the future, the mechanical property of phgraphene is further evaluated. It shows that phgraphene is a typically anisotropic material, which has not only direction-dependent Young's moduli but also direction-dependent even sign-changed Poisson's ratios. The microscopic mechanisms of both the electrical and mechanical properties are revealed. Such a versatile material with tunable band structure and auxetic effect should have promising applications in the advanced nano-electronic field in the future.
通过数值实验发现了一种由五边形和六边形元素组成的新型二维碳基材料，它被称为菲石墨烯，不仅具有可调谐的半金属特性，而且具有方向依赖的偶数符号变化的泊松比。首先系统地检查了这种新材料的结构稳定性。发现菲石墨烯具有与石墨炔相似的能量，石墨炔是一种从室温到1500 K的热稳定结构，且弹性常数满足玻恩-黄准则。用不同技术进一步验证了能带结构和态密度，证实了菲石墨烯的狄拉克半金属特性。一个更有趣的发现是，能带结构可以通过外部加载轻松调节，从而导致从半金属到半导体的转变或从I型到III型的转变。作为一种未来可能会被应用的新材料，进一步评估了菲石墨烯的力学性能。结果表明，菲石墨烯是一种典型的各向异性材料，不仅杨氏模量具有方向依赖性，而且泊松比也具有方向依赖的偶数符号变化。揭示了电学和力学性能的微观机制。这种具有可调谐能带结构和负泊松比效应的多功能材料在未来的先进纳米电子领域应该具有广阔的应用前景。
