Mechanical characterization of nanowires based on optical diffraction images of the bent shape.
Mechanical characterization of nanowires based on optical diffraction images of the bent shape.
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DOI：
10.1166/jnn.2009.1079
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发表时间：
2009-08
影响因子：
--
通讯作者：
M. Muraoka;Ryohei Tobe
中科院分区：
文献类型：
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作者：
M. Muraoka;Ryohei Tobe
基于弯曲试验下的光学显微观察，提出了一种长度超过约10微米的纳米线的力学表征技术。NWs的低抗弯刚度往往导致大挠度，这就排除了线性梁理论的使用；然而，大部分弯曲的形状是光学可见的衍射图像下透射照明。站在棒状基底上的NW通过微悬臂梁进行偏转，其中相互作用力，如范德华力，为固定NW的自由端提供了足够的附着力。用激光干涉仪测量悬臂梁挠度的反作用力。衍射图像的亮度分布提供了一个很好的测量NW直径。利用几何非线性力学对弯曲形状进行逆分析，可以成功地评估杨氏模量。此外，通过操纵悬臂梁进行了NW剧烈变形（如屈曲）的断裂测试。在弯曲NW的自由悬浮部分观察到最大曲率，其中断裂是确定的。弯曲强度是通过观察断裂处的曲率来确定的。以直径为40 ~ 190 nm的CuO NWs为例，表明杨氏模量和强度与NW直径有关。
A mechanical characterization technique for nanowires (NWs) longer than approximately 10 microm is proposed, based on optical microscopic observations under bending test. Low flexural rigidity of NWs often results in large deflection, which rules out the use of linear beam theory; however, the largely bent shape is optically visible as a diffraction image under transmitted illumination. The NW standing on a rod-like substrate was deflected by means of a micro-cantilever, where interactive forces, such as van der Waals forces, provide sufficient adhesion for fixing the free end of the NW. The reactive force was measured from the cantilever deflection and detected by a laser interferometer. The luminance profile of the diffraction image provided a good measure of the NW diameter. Inverse analysis using geometrically nonlinear mechanics for the bent shape enabled successful evaluation of the Young's modulus. In addition, a fracture test was conducted by manipulating the cantilever for intense deformation of the NW, such as buckling. The maximum curvature was observed at the freely suspended part of the bent NW where fracture was assured. The bending strength was determined from observation of the curvature at the fracture. Examples for CuO NWs of 40 nm to 190 nm in diameter indicated dependence of the Young's modulus and strength on the NW diameter.