Institute of High Performance Computing, A*STAR, Singapore 138632.
Nanoscale. 2018 May 24;10(20):9664-9672. doi: 10.1039/c8nr00308d.
Diamond nanothreads (DNTs) are a brand-new one-dimensional carbon nanomaterial that was synthesized recently by compressing benzene. Compared with sp2 carbon nanotubes, DNTs may possess a much higher interfacial load-transfer ability. However, previous studies have shown that the mechanical properties of DNTs are highly sensitive to the composition of Stone-Wales (SW) transformed sites. Up to now, it remained unclear what roles SWs play in the structure stability and how to engineer its molecular structure for novel mechanical properties. Using ab initio calculations, here we show that the most stable structure of a DNT is composed of alternative SW and hydrogenated carbon nanotube (3,0) units, suggesting that SW plays an essential role in stabilizing DNT. Interestingly, we found that the SW transition barrier is a nearly linear function of the applied strain, enabling strain engineering of its molecular structure. To do so, we propose a strain-temperature-stretching rate phase diagram to guide the construction of desired molecular structures to achieve superplastic behavior of DNTs. Our findings not only enrich our understanding of this novel carbon material, but also provide a strategy to control its structural and mechanical properties for novel applications, such as energy absorption, energy storage and materials reinforcement.
金刚石纳米线（DNTs）是一种全新的一维碳纳米材料，最近通过压缩苯合成。与 sp2 碳纳米管相比，DNTs 可能具有更高的界面载荷传递能力。然而，之前的研究表明，DNTs 的机械性能对 Stone-Wales（SW）转变位的组成非常敏感。到目前为止，SW 在结构稳定性中扮演什么角色以及如何设计其分子结构以获得新的机械性能仍不清楚。通过从头算计算，我们在这里表明，DNT 的最稳定结构由交替的 SW 和氢化碳纳米管（3,0）单元组成，这表明 SW 在稳定 DNT 中起着重要作用。有趣的是，我们发现 SW 转变势垒是施加应变的近乎线性函数，使分子结构的应变工程成为可能。为此，我们提出了应变-温度-拉伸速率相图来指导所需分子结构的构建，以实现 DNTs 的超塑性行为。我们的发现不仅丰富了对这种新型碳材料的理解，而且为控制其结构和机械性能提供了一种策略，以实现新的应用，如能量吸收、能量存储和材料增强。
