Sun Jie, Chen Yanyan, Wang Qian
Center for Applied Physics and Technology, HEDPS, College of Engineering, and School of Materials Science and Engineering, BKL-MEMD, Peking University, Beijing 100871, China.
Phys Chem Chem Phys. 2021 Mar 11;23(9):5460-5466. doi: 10.1039/d0cp06390h.
5-8-defects are well-known in graphene and other 2D carbon structures, but not well-studied in one dimensional (1D) carbon materials. Here, we design a peanut-shaped carbon nanotube by assembling the 5-8-cage composed of carbon 5- and 8-membered rings, named 5-8-PSNT. Using first-principles calculations and molecular dynamics simulations, we find that 5-8-PSNT is not only thermally and dynamically stable, but also metallic. Moreover, its lattice thermal conductivity is only 95.87 W m-1 K-1, which is less than one tenth of the value of (6, 6) carbon nanotube that has a radius similar to that of 5-8-PSNT. A further analysis of the phonon properties reveals that the low lattice thermal conductivity of 5-8-PSNT arises from its low phonon group velocity, short relaxation time, large lattice vibrational mismatch and strong anharmonicity. These findings further suggest that a pentagon and an octagon as structural units can effectively modulate the properties of carbon materials.
5-8缺陷在石墨烯和其他二维碳结构中是众所周知的，但在一维（1D）碳材料中却没有得到充分研究。在这里，我们通过组装由碳五元环和八元环组成的5-8笼来设计一种花生形碳纳米管，命名为5-8-PSNT。通过第一性原理计算和分子动力学模拟，我们发现5-8-PSNT不仅热稳定性和动力学稳定性良好，而且具有金属性。此外，其晶格热导率仅为95.87 W m-1 K-1，不到半径与5-8-PSNT相似的（6,6）碳纳米管值的十分之一。对声子特性的进一步分析表明，5-8-PSNT的低晶格热导率源于其低声子群速度、短弛豫时间、大晶格振动失配和强非谐性。这些发现进一步表明，五边形和八边形作为结构单元可以有效地调节碳材料的性能。
