Kaplan-Ashiri Ifat, Cohen Sidney R, Gartsman Konstantin, Ivanovskaya Viktoria, Heine Thomas, Seifert Gotthard, Wiesel Inna, Wagner H Daniel, Tenne Reshef
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
Proc Natl Acad Sci U S A. 2006 Jan 17;103(3):523-8. doi: 10.1073/pnas.0505640103. Epub 2006 Jan 9.
The mechanical properties of materials and particularly the strength are greatly affected by the presence of defects; therefore, the theoretical strength ( approximately 10% of the Young's modulus) is not generally achievable for macroscopic objects. On the contrary, nanotubes, which are almost defect-free, should achieve the theoretical strength that would be reflected in superior mechanical properties. In this study, both tensile tests and buckling experiments of individual WS(2) nanotubes were carried out in a high-resolution scanning electron microscope. Tensile tests of MoS(2) nanotubes were simulated by means of a density-functional tight-binding-based molecular dynamics scheme as well. The combination of these studies provides a microscopic picture of the nature of the fracture process, giving insight to the strength and flexibility of the WS(2) nanotubes (tensile strength of approximately 16 GPa). Fracture analysis with recently proposed models indicates that the strength of such nanotubes is governed by a small number of defects. A fraction of the nanotubes attained the theoretical strength indicating absence of defects.
材料的力学性能，尤其是强度，会受到缺陷的显著影响；因此，宏观物体通常无法达到理论强度（约为杨氏模量的10%）。相反，几乎无缺陷的纳米管应该能够达到理论强度，这将体现在优异的力学性能上。在本研究中，在高分辨率扫描电子显微镜下对单个WS(2)纳米管进行了拉伸试验和屈曲实验。还通过基于密度泛函紧束缚的分子动力学方案模拟了MoS(2)纳米管的拉伸试验。这些研究的结合提供了断裂过程本质的微观图景，有助于深入了解WS(2)纳米管的强度和柔韧性（拉伸强度约为16 GPa）。用最近提出的模型进行的断裂分析表明，此类纳米管的强度受少量缺陷控制。一部分纳米管达到了理论强度，表明不存在缺陷。
