Department of Mechanical Engineering and Materials Science, ‡Department of Chemistry, and §Smalley Institute for Nanoscale Science and Technology, Rice University , Houston, Texas 77005, United States.
ACS Nano. 2013 Nov 26;7(11):10075-82. doi: 10.1021/nn404177r. Epub 2013 Oct 10.
We report an extensive study of the properties of carbyne using first-principles calculations. We investigate carbyne's mechanical response to tension, bending, and torsion deformations. Under tension, carbyne is about twice as stiff as the stiffest known materials and has an unrivaled specific strength of up to 7.5 × 10(7) N·m/kg, requiring a force of ∼10 nN to break a single atomic chain. Carbyne has a fairly large room-temperature persistence length of about 14 nm. Surprisingly, the torsional stiffness of carbyne can be zero but can be "switched on" by appropriate functional groups at the ends. Further, under appropriate termination, carbyne can be switched into a magnetic semiconductor state by mechanical twisting. We reconstruct the equivalent continuum elasticity representation, providing the full set of elastic moduli for carbyne, showing its extreme mechanical performance (e.g., a nominal Young's modulus of 32.7 TPa with an effective mechanical thickness of 0.772 Å). We also find an interesting coupling between strain and band gap of carbyne, which is strongly increased under tension, from 2.6 to 4.7 eV under a 10% strain. Finally, we study the performance of carbyne as a nanoscale electrical cable and estimate its chemical stability against self-aggregation, finding an activation barrier of 0.6 eV for the carbyne-carbyne cross-linking reaction and an equilibrium cross-link density for two parallel carbyne chains of 1 cross-link per 17 C atoms (2.2 nm).
我们使用第一性原理计算对碳炔的性质进行了广泛的研究。我们研究了碳炔在拉伸、弯曲和扭转变形下的力学响应。在拉伸下，碳炔的硬度大约是已知最硬材料的两倍，具有无与伦比的比强度高达 7.5×10(7) N·m/kg，需要大约 10 nN 的力才能断裂单根原子链。碳炔在室温下具有相当大的持久长度，约为 14 nm。令人惊讶的是，碳炔的扭转刚度可以为零，但可以通过末端的适当官能团“开启”。此外，在适当的终止条件下，碳炔可以通过机械扭转转变为磁性半导体状态。我们重构了等效连续体弹性表示，为碳炔提供了完整的弹性模量，展示了其极端的机械性能（例如，名义杨氏模量为 32.7 TPa，有效机械厚度为 0.772 Å）。我们还发现了碳炔应变和带隙之间有趣的耦合，在拉伸下，应变从 2.6 增加到 4.7 eV。最后，我们研究了碳炔作为纳米级电缆的性能，并估计了其对自聚集的化学稳定性，发现碳炔-碳炔交联反应的活化能为 0.6 eV，并且两条平行碳炔链之间的平衡交联密度为每 17 个 C 原子 1 个交联（2.2 nm）。
