Electron-beam-assisted superplastic shaping of nanoscale amorphous silica

Abstract

At room temperature, glasses are known to be brittle and fracture upon deformation. Zheng et al. show that, by exposing amorphous silica nanostructures to a low-intensity electron beam, it is possible to achieve dramatic shape changes, including a superplastic elongation of 200% for nanowires.

The Mechanical Properties of Nanowires

“…As shown in Figure 13 , fractures were generated in an Al 2 O 3 NW loop when it was examined during TEM imaging 146. Previous studies have also shown that EBI may increase the plasticity of NaCl,142 SiO 2 138 and Si NWs,147 weaken the strength of Al 2 O 3 NWs,146 stiffen zinc tin oxide NWs,148 and significantly decrease the fatigue life of ZnO NWs 149. Also, EBI during SEM imaging may generate pits in the shell structure of carbon nanotubes 150.…”

“…Thermal effect and knock‐on effect from energetic electrons in TEM or SEM may contribute to NW specimens damage 136. Thermal effect induced by energetic electrons is difficult to quantify, however recent studies have revealed that the temperature increase of a NW sample during a normal TEM imaging process is far below 100 °C 99, 102, 137, 138. Therefore thermal effect should insignificantly alter the properties of NWs.…”

“…Knock‐on effects can be evaluated by considering the threshold displacement energy (TDE), that is the minimum amount of kinetic energy transferred to a lattice atom resulting in the formation of a stable Frenkel pair 136. However, sub‐threshold irradiation, which can significantly affect defect migration or induce local chemical reactions in NW samples,136, 139, 140, 141 has rarely been considered with regards to strained NWs 138, 142. In addition, it should be noted that the existing TDE value for a specific material is measured in a stress‐free state, which might not hold for specimens under strain.…”

“…Any method has a systematic error, such as the nonlinearity error in bending tests, substrate and confinement effects in nanoindentation tests,31, 77 uncertainty in boundary conditions for resonant vibration tests,170, 242, 243, 244 and EBI‐induced effects for in situ EM tests 138, 142, 146, 147, 148. In addition, misalignment can significantly affect the measured mechanical properties.…”

In situ study of the mechanical properties of airborne haze particles

“…The accelerating voltage of the electron gun was set to be 10 kV during the test in order to reduce the potential beam damage. The contact pressure was defined as the applied force divided by the contact area between the particle and substrate assuming a perfect circular contact [10][11][12], and the compression ratio was defined as the compressive displacement (u) (after subtracting the contribution from the substrate) divided by the particle diameter (D) in our study. The H c was defined as the contact pressure at the point of yield for brittle particles or the peak contact pressure for ductile particles.…”