Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575, USA.
Nanotechnology. 2011 Jul 22;22(29):295709. doi: 10.1088/0957-4484/22/29/295709. Epub 2011 Jun 20.
We describe the development of a technique for making indentations on the top 5-20 nm of the surfaces of relatively low modulus materials using a high spatial and force sensitivity atomic force microscope (AFM) whose optical cantilever has been replaced by a quartz crystal resonator (QCR). Unlike conventional optical-cantilever-based AFMs, the accuracy of this technique is not compromised by the compliance of the loading system due to the high stiffness of the QCR. To obtain material modulus values from the indentation results, we find the commonly used Oliver-Pharr model to be unsuitable because of our use of a sharp tip and relatively deep indentation. Instead, we develop a new analysis that may be more appropriate for the geometry we use as well as the non-linear constitutive behavior exhibited by the materials we examined. We calculated values for the moduli of several different materials, which we find to be consistent with the range of published data.
我们描述了一种在相对低模量材料的表面上进行压痕的技术的发展，该技术使用高空间和力灵敏度原子力显微镜（AFM），其光学悬臂梁已被石英晶体谐振器（QCR）取代。与传统的基于光学悬臂梁的 AFM 不同，由于 QCR 的高刚度，该技术的精度不会因加载系统的顺应性而受到影响。为了从压痕结果中获得材料的模量值，我们发现常用的 Oliver-Pharr 模型由于我们使用的是尖锐的尖端和相对较深的压痕而不适用。相反，我们开发了一种新的分析方法，该方法可能更适合我们使用的几何形状以及我们所研究的材料表现出的非线性本构行为。我们计算了几种不同材料的模量值，发现这些值与已发表数据的范围一致。
