原位通孔鼓泡法测试二维材料杨氏模量

Measurement of Young′s modulus for 2D materials by in situ through-hole bubble method

二维材料因其独特的晶体结构、新奇的物理特性和优异的力学性能,在光电器件、微纳机电系统等诸多领域有着广阔的应用前景,其中力学性能对于器件的制备、功能性、稳定性以及服役寿命等方面尤为重要。本文提出了一种测量二维材料杨氏模量的普适性实验方法,借助通孔鼓泡技术对材料进行连续可控加载,同时结合原子力探针技术原位表征其力学响应。该技术较好地解决了文献中常用恒定分子数鼓泡技术在测试二维材料杨氏模量中存在的加载周期长、加载不连续等弊端。以单层或双层石墨烯薄膜为例,利用自行搭建的通孔鼓泡实验平台结合原子力显微技术实现了鼓泡高度和直径大小的原位测量,借助Hencky解获得石墨烯杨氏模量,实验数值与文献报道相符。此外,在三角波和正弦波两种动态循环加载方式下,该测试方法均表现出良好的稳定性。本文工作不仅发展了一种普适原位的二维材料杨氏模量实验测试方法,也为大面积二维材料薄膜力学性能的程序化测试与分析、高通量实验数据的力学统计分析打下了可靠的实验基础。

Owing to the unique crystal structures and novel physical properties, two-dimensional (2D) materials have exihibited huge potential in a variety of application fields, such as optoelectronic devices, micro-/nano-electromechanical systems (MEMS/NEMS), etc. Among them, mechanical properties are crucial for the fabrication, functionality, stability and lifetime of nanodevices, thus calling for universal and accurate experimental measurements. In this work, a universal through-hole bubble test method for measuring Young's modulus of 2D materials is proposed, which can simutaneously realize continuous loading and in situ AFM characterization of mechanical response under controllable pressures. This technology overcomes the shortcomings of the constant molecular number bubbling technology in testing Young's modulus of 2D materials, such as long loading period and discontinuous loading. Taking monolayer and bilayer graphene as examples, the height and diameter of bubbles can be measured in situ by the through-hole bubble test combined with AFM. On the basis of the Hencky solution, the Young's moduli are obtained which are consistent with those reported in literatures. Moreover, this method shows excellent stability under triangular wave and sinusoidal wave cyclic loading. This work not only evidences the universality of througth-hole bubble test as an in situ method for measuring Young's modulus of 2D materials, but also establishs a reliable experimental foundation for programmed measurement and analysis of mechanical properties of large-area 2D materials and mechanical statistical analysis of high-throughput experimental data.