Fracture Mechanics of Nanowires and Nanostructures

理想晶体的强度一直是人们感兴趣的，但“真实的”材料具有较低的强度，因为它们具有缺陷。纳米结构的失效方式可能与较大结构不同，因此研究纳米结构如何断裂（断裂）提供了一个将“真实的”与“理想的”联系起来的机会。这项对具有新颖结构的纳米线断裂的研究由于其电学，热学和机械性能而非常重要，包括美国，瑞典和韩国的合作者，他们将提供纳米线进行机械测试。一种新的微机电（“基于MEMS”）机械加载平台，可以在透射电子显微镜内操作，具有亚纳米分辨率，将与其他微小的测试设备一起沿着使用，以找出是什么使纳米线断裂。纳米线可用于纳米电子学（作为逻辑和存储器和互连元件），由于它们的高表面体积比和对表面相互作用的异常敏感性，在纳米机电系统中作为化学传感元件，（NEMS;作为机械部件、机电部件、致动器、应变仪、流量传感器等），以及在结构复合材料中，其中纳米线的晶体完美性预期赋予优异的刚度、强度和韧性。因此，重要的是要了解单晶纳米线的详细力学，以便知识基础可以用于其随后在机械应力将存在的各种应用中的使用。这项工作包括研究生和博士后研究员的研究计划，本科生和高中教师的夏季研究培训，以及其他教育活动。

The strength of an ideal crystal has long been of interest but 'real' materials have lower strengths because they have defects. Nanostructures can fail differently from larger structures, so studies of how nanostructures will break (fracture) provide an opportunity to connect the 'real' to the 'ideal'. This study of fracture in nanowires having novel structures that are important due to their electrical, thermal, and mechanical properties includes collaborators in the United States, Sweden, and South Korea who will provide nanowires for mechanical testing. A new microelectromechanical ('MEMS-based') mechanical loading stage that can operate inside a transmission electron microscope with sub-nanometer resolution will be used along with other tiny testing devices to find out what makes nanowires break. Nanowires may be used in nanoelectronics (as logic and memory and interconnect elements), as chemical sensing elements due to their high surface to volume ratio and exceptional sensitivity to surface interactions, in nanoelectromechanical systems (NEMS; as mechanical components, electromechanical components, actuators, strain gauges, flow sensors, others), and in structural composites where the crystalline perfection of nanowires is expected to confer exceptional stiffness, strength, and toughness. It is thus important to understand the detailed mechanics of single crystal nanowires so a base of knowledge can be available for their subsequent use in diverse applications where mechanical stress will be present. This effort includes research programs for graduate students and postdoctoral fellows, summer research training for undergraduate students and high school teachers, and other educational activities.