Uniform e-beam irradiation-induced athermal straightening of axially curved amorphous SiO_x nanowires

Abstract

The reshaping of amorphous SiOx nanowires (a-SiOx NWs) as purely induced by uniform electron beam (e-beam) irradiation was in-situ studied at room temperature in transmission electron microscope. It was observed that the axially straight NW kept its perfect straight cylinder-like wire shape and demonstrated a sequential uniform radial shrinkage with the increase of irradiation time. In contrast, the axially curved NW turned straight quickly accompanied with a uniform axial shrinkage and a uniform radial expansion intriguingly. It is expected that such a study especially on the straightening of axially curved NW has important implications for the nanoscale processing and stability of future NW-based structures or devices. More importantly, the findings demonstrate that the traditional knock-on mechanism and electron beam heating effect are inadequate to explain these processes while our proposed nanocurvature effect and energetic beam-induced athermal activation effect obviously dominate the processes.

Electron beam-induced athermal nanowelding of crossing SiOx amorphous nanowires

“…Therefore, we predicted that there must be two mechanisms, which are intrinsic to the crossed amorphous NWs under the irradiation to drive the athermal plastic flow of massive atoms: (1) the high surface energy of the NW gives rise to a strong, thermodynamic tendency for the wires to self-contract, and (2) the e-beam irradiation athermally softens the welded wires and kinetically activates the contraction and the plastic flow. Irradiation-induced fast diffusion of atoms has also been observed to induce straightening of bent SiO x nanowires 34 and elongation together with the radial shrinkage of straight SiO x nanowires. 35 Moreover, gold nanoparticles 36 have been observed to coalesce under uniform e-beam irradiation.…”