NER: Exploring the Mechanical and Thermoelectric Properties of Composite Nano-Rods and Nano-Springs

该补助金探索了最近使用掠角沉积（GLAD）技术开发的一类新型纳米结构的机械和热电性能的实验研究。该结构是以纳米棒和纳米弹簧的形式垂直于衬底或与衬底成一定角度生长并彼此对齐。杆的纵横比、间距和对称性可以随意选择。该结构可以由元素、合金和多层形式的多种材料制成。这些条件是材料表征的理想条件。从力学上讲，纳米棒是用于宏观尺度材料表征的圆柱形宏观样品的纳米级等效物。一个主要的目标是加载的纳米棒与AFM或纳米压头尖端在轴向压缩和弯曲。这种技术提供了巨大的优势，在纳米尺度的纳米压痕标准测量。单个纳米棒的热电优值将通过将电流从导电AFM针尖通过纳米棒传递到底部导电衬底而从测量的塞贝克电压获得。沿着实验研究，几个理论问题将得到解决，包括材料性能与试样尺寸的比例和梯度非线性本构方程的有效性，这是一项探索性研究，将测试材料特性中缩放概念的极限，从而为未来NEMS和能量转换设备中的各种应用提供新的纳米级材料组合的设计和发现指导。所提出的多学科方法与物理学，材料科学和机械工程组件，如果成功，将显着推进纳米结构的机械和热电测量领域。

The grant explores a an experimental study of the mechanical and thermoelectric properties of a novel class of nanostructures that have been developed recently using the grazing angle deposition (GLAD) technique. The structures are in the form of nanorods and nanosprings grown perpendicular or at an angle to the substrate and aligned with each other. The aspect ratio, spacing and symmetry of the rods may be selected at will. The structures can be made from a large variety of materials in the elemental, alloy and multilayered form. These conditions are ideal for material characterization. Mechanically, the nanorods are the nanoscale equivalent of the cylindrical macroscopic specimens used for material characterization at the macroscale. A major objective is to load the nano-rods with an AFM or a nanoindenter tip both in axial compression and in bending. This technique offers tremendous advantages over the standard measurements made at the nanoscale by nanoindentation. The thermoelectric figure of merit of a single nanorod will be obtained from the measured Seebeck voltage by passing a current from a conductive AFM tip through the nanorod to the bottom conducting substrate.Along with the experimental study, several theoretical issues will be addressed that include the scaling of material properties with specimen size and the validity of constitutive equations of the gradient non-local type material behavior at the nanoscale.This is an exploratory research that will test the limit of the scaling concept in materials properties thereby providing guidance to the design and discovery of new nanoscale material combinations for various applications in future NEMS and energy conversion devices. The proposed multidisciplinary approach with Physics, Materials Science, and Mechanical Engineering components, if successful, will significantly advance the field of mechanical and thermoelectric measurements of nanostructures.