Intriguing uniform elongation and accelerated radial shrinkage in an amorphous SiOx nanowire as purely induced by uniform electron beam irradiation

摘要

At room temperature, an intriguing athermal uniform elongation and accelerated radial shrinkage in a straight and uniform amorphous SiOx nanowire (a-SiOx NW) as purely induced by uniform electron beam (e-beam) irradiation (without any external tensile pulling) was in situ observed and investigated in transmission electron microscope. According to a new model for NW taking into account the NW nanocurvature over its surface as well as the beam-induced athermal activation, a kinetic relationship between the shrinking radius and the irradiation time was established. The fitting results demonstrated that a curvature-dependent surface energy at the nanoscale (so-called nanocurvature effect) much higher than that predicted from the existing theories was exerted on the elongation and shrinkage of the NW. At the same time, the so-induced plastic flow of massive atoms and surface diffusion of atoms presented as well a further direct experimental evidence for our predicted soft mode and instability of atomic vibration as induced under energetic beam irradiation in amorphous materials. The study has important implications for the nanoprocessing or nanostability of future NW-based structures or devices. More importantly, it further demonstrates that the nanocurvature effect and the beam-induced atomic vibration soft mode and instability effect, which have been normally neglected or inadequately taken into account in the current literature, are universal concepts and applicable to explanation of energetic beam-induced nanoinstability or nanoprocessing of low dimensional nanostructure in general.