Experimental Investigation of Fundamental Mechanical Behavior of Silicon Nanowires

这项研究是关于硅纳米线的弹性、断裂的尺寸效应与其脆韧性转变之间的关系。对同一单个核心筒进行原位扫描/透射电子显微镜共振和拉伸试验，以测量其弹性行为。将使用统计的威布尔类型的概率模型来分析裂缝数据，并在实时和尸检显微镜分析的辅助下识别裂缝来源。利用一种新颖的微加工测试平台，在透射电子显微镜中进行原位热机械测试，将被用来探测脆性到韧性的转变。如果成功，拟议的研究将有可能改进柔性和可拉伸的电子学，改善能量转换和存储。预计实验结果将以一种合作的方式用于开发原子模拟，从而确定纳米级弹性、断裂和脆性到韧性转变的基本机制。此外，在该项目中开发的新的实验工具和方法(例如，微制造热机械测试阶段)可以用于了解广泛的纳米结构的性质。从教学的角度来看，这项工作将是：1)融入国际和平研究所在NCSU提供的本科生和研究生课程(包括NSF资助的本科生纳米技术实验室课程)，并在网上传播新的课程模块；2)用于培训研究生和本科生进行有女性和代表性不足的少数民族参与的多学科研究；3)用于与北卡罗来纳州立大学的工程场所项目合作，开发一个互动演示模块，并将其呈现给K-12学生。

This research is about the correlation between the size effects of silicon nanowires on elasticity, fracture, and their brittle to ductile transition.. In-situ scanning/transmission electron microscopy resonance and tensile testing on the same single NWs will be conducted to measure the elastic behavior. A statistical, Weibull-type, probability model will be employed to analyze the fracture data and identify fracture origins with the assistance of real-time and post-mortem microscopy analyses. In-situ thermomechanical testing done in-situ, in a Transmission Electron Microscope using a novel microfabricated testing stage will be used to probe the brittle to ductile transition.If successful, the proposed research has potential to improve flexible and stretchable electronics, improve energy conversion and storage. It is anticipated that the experimental results will be used in a collaborative way to develop atomistic simulations that will pin down the mundamental mechnisms of nanoscale elasticity, fracture and brittle to ductile transition. In addition, the novel experimental tools and methods developed in this project (e.g., the microfabricated thermomechanical testing stage) can be used to understand the properties of a broad range of nanostructures. From a teaching perspective, this work will be: 1) integrated into undergraduate and graduate courses that PI offers at NCSU (including a NSF supported undergraduate nanotechnology laboratory course), and web-based dissemination of the new course module; 2) used for training of graduate and undergraduate students for multidisciplinary research with involvement of women and underrepresented minorities; 3) used for collaboration with the Engineering Place program at North Carolina State University to develop an interactive demonstration module and present it to K-12 students.