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

Abstract

At room temperature, an intriguing athermal uniform elongation and accelerated radial shrinkage in a straight and uniform amorphous SiO x nanowire (a-SiO x 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.

Electron beam-induced athermal nanowelding of crossing SiOx amorphous nanowires

“…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. These phenomena are driven by the structural instability with the help of the athermal activation effect of e-beam irradiation.…”

Passivation Effect of Gold Nanoparticles on Uniform Beam-Induced Structural Changes of Amorphous SiOx Nanowire

“…Even more intriguingly, as also demonstrated in Figure 5, the shrinkage of the pristine NW started to become faster and faster when the radius reduced down to about 7 nm after 900 s irradiation whereas the accelerated radial shrinkage tendency of the AuNPs-modified NW seemed much less pronounced. According to a new modeling on kinetic relationship between the shrinking wire radius and the beam irradiation time where a key parameter b (the definition is similar to that in the case of single-walled carbon nanotube (SWCNT) 15 ) has been particularly established for the nanocurvature effect of NW on the NW surface energy, 19 we obtained a well-fitted value of the constant b at ∼2.4 for the AuNPs-modified NW and ∼3.3 for the pristine NW as shown in Figure 5. The fitting result that the constant b for the AuNPs-modified NW is much smaller than that for the pristine NW indicated that the nanocurvedsurface energy for the AuNPs-modified NW became much smaller than that for the pristine NW once being decorated by AuNPs on the wire surface.…”

Current-induced restructuring in bent silver nanowires

“…It is known that resonance in nanostructures can be induced by electrostatic forces, 70,71 electromagnetic forces, 72 opto-thermal effects 73 or electron beam exposure. 74,75 During our experiments, the energy of the electron beam (300 keV) and the magnetic field created by the electromagnetic lenses in the TEM remained unaltered. On the other hand, the current passing through the Ag NW was continuously increased.…”