Department of Materials Science and Engineering, College of Materials, and Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University , Xiamen, Fujian 361005, China.
International Centre for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS) , Namiki 1-1, Tsukuba, Ibaraki 3050044, Japan.
Nano Lett. 2016 Aug 10;16(8):5221-7. doi: 10.1021/acs.nanolett.6b02287. Epub 2016 Jul 29.
The structural defects that inevitably exist in real-world carbon nanotubes (CNTs) are generally considered undesirable because they break the structural perfection and may result in drastically degraded CNT properties. On the other hand, the deliberate defect introduction can provide a possibility to tailor the tube mechanical properties. Herein, we present a fully controllable technique to handle defects by using in situ transmission electron microscopy (TEM). Young's modulus, quality factor of the resonation and tensile strength of CNTs can be controllably, reversibly, and repeatedly tuned. Parallel high-resolution visualizing of structural defects suggests that the property tuning cycles are primarily attributed to the reversible conversion of defects at the atomic scale: the defects are created in the form of vacancies and interstitials under electron irradiation, and they vanish through the recombination via current-induced annealing. For applications, such as reversible frequency-tuned CNT resonators, this defect-engineering technique is demonstrated to be uniquely precise; the frequency may be tuned with 0.1%/min accuracy, improved by 1 order of magnitude compared with the existing approaches. We believe that these results will be highly valuable in a variety of property-tunable CNT-based composites and devices.
在现实世界中的碳纳米管（CNTs）中不可避免地存在结构缺陷，这些缺陷通常被认为是不理想的，因为它们破坏了结构的完美性，并可能导致 CNT 性能急剧下降。另一方面，故意引入缺陷可以提供一种调整管体力学性能的可能性。在此，我们提出了一种通过原位透射电子显微镜（TEM）处理缺陷的完全可控技术。碳纳米管的杨氏模量、共振的品质因数和拉伸强度可以可控、可逆和反复地进行调整。对结构缺陷的平行高分辨率可视化表明，这种性能调整循环主要归因于原子尺度上缺陷的可逆转换：在电子辐照下，缺陷以空位和间隙的形式产生，通过电流诱导退火的复合作用，它们消失。对于可逆频率调谐 CNT 谐振器等应用，这种缺陷工程技术被证明是非常精确的；与现有方法相比，频率可以以 0.1%/min 的精度进行调整，提高了一个数量级。我们相信，这些结果将在各种可调性 CNT 基复合材料和器件中具有很高的价值。
