Nanomechanical Property Evaluation by using Ultrasonic Atomic Force Microscope

使用超声波原子力显微镜评估纳米力学性能

基本信息

批准号：
10450016
负责人：
YAMANAKA Kazushi
金额：
$ 7.62万
依托单位：
Tohoku University (2000)Institute of Applied Physics, University of Tsukuba (1998-1999)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

For a quantitative evaluation of nano-scale elasticity, ultrasonic atomic force microscopy(UAFM)and related methods measure the contact stiffness(or force gradient)between the tip and sample surface. In these methods the key parameter is the contact radius, since the contact stiffness is changed not only by the elasticity of sample but also by the contact radius. However, the contact radius, is very uncertain and it makes the precision of measurements questionable. In this work we propose a novel in-situ method to estimate the tip shape and the contact radius at the nano-scale contact of the tip and sample. Because the measured resonance frequency sometimes does not depend so sensitively on the contact as expected from the parabolic tip model, we introduced a more general model of an axial symmetric body and derived an equation for the contact stiffness. Then the parameters in the model are unambiguously determined from a contact force dependence of the cantilever resonance frequency. … More We verified that this method is able to provide an accurate prediction of the cantilever thickness, the tip shape, and the effective elasticity of soft and rigid samples.As applications we evaluated machining damage and lattice defects. Graphite is an important material for use as a solid lubricant that works even at high temperature. Generally, the reason for the lubricity is that carbon layers easily side against each other due to the layered structure with weak interlayer interaction. However, the atomic nature of the interlayer interaction is still not fully unederstood. To improve this understanding, we applied UAFM to highly oriented pyrolytic graphite and observed edge dislocations accompanied by extra half-planes. From observation of the dislocation behavior under different loads, we found that the dislocation moved laterally by 20 nm as the load increased by 80 nN, and it returned to the original position as the load decreased. To explain this result, we proposed a model for the lateral displacement of the dislocation, which includes a spring and pinning point. This finding of the large lateral displacement confirms the extraordinarily easy sliding between carbon layers, it is relevant to the performance as a solid lubricant. It may also be relevant to the significant material transport in graphite intercalation compounds. Less

为了定量评估纳米级弹性，超声原子力显微镜（UAFM）和相关方法测量了尖端和样品表面之间的接触刚度（或力梯度）。在这些方法中，关键参数是触点半径，因为接触刚度不仅通过样品的弹性更改，而且通过接触半径改变。但是，接触半径是非常不确定的，并且使测量的精度值得怀疑。在这项工作中，我们提出了一种新型的原位方法，以估计尖端和样品的纳米级接触处的尖端形状和接触半径。由于测得的共振频率有时不像抛物线尖端模型所期望的接触那样敏感，因此我们引入了更通用的轴向对称体模型，并得出了一个方程式的接触刚度。然后，模型中的参数由悬臂共振频率的接触力依赖性明确确定。 …更多，我们验证了该方法能够准确预测悬臂厚度，尖端形状以及柔软和刚性样品的有效弹性。作为应用，我们评估了加工损伤和晶格缺陷。石墨是作为固体润滑剂使用的重要材料，即使在高温下也可以使用。通常，润滑性的原因是碳层由于层间相互作用较弱的分层结构而容易相互对立。然而，层间相互作用的原子质仍然没有完全尚未被列出。为了提高这种理解，我们将UAFM应用于高度定向的热解石墨，并观察到的边缘位错，并伴随着额外的半平台。从观察到不同载荷下的位错行为，我们发现，随着载荷增加80 nn的增加，脱位横向移动20 nm，并且随着负载降低，脱位又返回到原始位置。解释这一结果，我们提出了一个模型，用于脱位的横向位移，其中包括弹簧和固定点。大型横向位移的发现证实了碳层之间非常简单的滑动，它与作为固体润滑剂的性能相关。它也可能与石墨插入化合物中的重要材料转运有关。较少的