Experimental nanomechanics of one-dimensional nanomaterials by in situ microscopy

This paper provides a comprehensive review on the methodological development and technical applications of in situ microscopy, including transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM), developed in the last decade for investigating the structure-mechanical-property relationship of a single one-dimensional nanomaterial, such as nanotube, nanowire and nanobelt. The paper covers both the fundamental methods and detailed applications, including AFM-based static elastic and plastic measurements of a carbon nanotube, external field-induced resonance dynamic measurement of elastic modulus of a nanotube/nanowire, nano-indentation, and in situ plastic deformation process of a nanowire. Details are presented on the elastic property measurements and direct imaging of plastic to superplastic behavior of semiconductor nanowires at atomic resolution, providing quantitative information on the mechanical behavior of nanomaterials. The studies on the Si and SiC nanowires clearly demonstrated their distinct, unexpected and superior plastic mechanical properties. Finally, a perspective is given on the future of nanomechanics.