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

TL;DR

This study reveals that uniform electron beam irradiation causes athermal uniform elongation and radial shrinkage in amorphous SiOx nanowires, driven by nanocurvature effects and beam-induced atomic vibrations, impacting nanostructure stability and processing.

Contribution

It introduces a new model incorporating nanocurvature and beam-induced atomic vibrations to explain nanowire deformation under electron irradiation, highlighting previously neglected effects.

Findings

Uniform elongation and radial shrinkage observed without external tension.

A curvature-dependent surface energy significantly higher than existing predictions.

Experimental evidence of atomic vibration soft mode and instability under irradiation.

Abstract

An intriguing athermal uniform elongation and accelerated radial shrinkage in amorphous SiOx nanowire (a-SiOx NW) as purely induced by uniform electron beam (e-beam) irradiation were in-situ investigated in transmission electron microscope. It was observed that at room temperature the straight and uniform a-SiOx NW demonstrated a uniform plastic elongation (without any external tensile pulling) and a corresponding uniform radial shrinkage. According to a new model 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 is exerted on the elongation and shrinkage of the NW. At the same time, the so-induced plastic flow of massive atom and surface diffusion of atom presented as well a further direct experimental evidence for our predicted soft mode and instability of atomic vibration as induced under energetic beam (including e-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.