Mechanical Properties of Nanowires and Nanobelts
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Because of the high size and structure selectivity of nanomaterials, their physical properties could be quite diverse, depending on their atomic-scale structure, size, and chemistry. To maintain and utilize the basic and technological advantages offered by the size specificity and selectivity of the nanomaterials, there are three key challenges that we need to overcome for the future technological applications of nanomaterials. First, synthesis of size, morphology and structurally controlled nanomaterials, which are likely to have the precisely designed and controlled properties. Secondly, novel techniques for characterizing the properties of individual nanostructures and their collective properties. This is essential for understanding the characteristics of the nanostructures. Finally, integration of nanomaterials with the existing technology is the most important step for their applications, especially in nanoscale electronics and optoelectronics.
Characterizing the mechanical properties of individual nanotubes/nanowires/nanobelt [called one-dimensional (1-D) nanostructure] is a challenge to many existing testing and measuring techniques because of the following constrains. First, the size (diameter and length) is rather small, prohibiting the applications of the well-established testing techniques. Tensile and creep testing require that the size of the sample be sufficiently large to be clamped rigidly by the sample holder without sliding. This is impossible for 1-D nanomaterials using conventional means. Secondly, the small size of the nanostructure makes their manipulation rather difficult, and specialized techniques are needed for picking up and installing individual nanostructure. Therefore new methods and methodologies must be developed to quantify the properties of individual nanostructure. The objective of this chapter is to introduce the theory and techniques that have developed for characterizing the mechanical properties of individual nanotubes/nanowires/nanobelt using in situ transmission electron microscopy (TEM).