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(a) TEM image of the morphologies of the as-grown SiO2 nanowires. (b) Magnified TEM image of the SiO2 nanowire. SiO2 nanowires covered with gold nanoparticles are shown. (c) High-resolution TEM image of the SiO2 nanowire showing the gold nanoparticles on the surface or embedded in SiO2, as indicated by circles. The inset shows the SAED pattern, which exhibits an amorphous SiO2 structure with gold crystals (diffraction spots, as indicated by circles). Different colors were used to divide different crystal planes. (d) The two SiO2 nanowires were welded together under e-beam irradiation and then (e) stretched. Finally, (f) two tips are formed after breaking apart, those were subscribed to evaporation. Bar in (a) 500 nm; (b) and (d) 100 nm; (c) 5 nm; (e) 10 nm; (f) 20 nm.
Sequence TEM images ((a)–(d) under Iebeam ∼ 140 ± 20 A cm−2, and (e)–(h) under Iebeam ∼ 10 A cm−2, respectively) showing the diffusion and evaporation processes from the SiO2 tip. Semi-sphere shaped tips were observed during evaporation. The blue dashed lines were drawn as references. Diffusion of inclusions was noted in the images by dashed orange lines and arrows. Bar for (a)–(d) is 10 nm, for (e)–(h) is 50 nm (enhanced online). Video 1, Video 2, Video 3. [URL: http://dx.doi.org/10.1063/1.4765662.1] [URL: http://dx.doi.org/10.1063/1.4765662.2] [URL: http://dx.doi.org/10.1063/1.4765662.3]10.1063/1.4765662.110.1063/1.4765662.210.1063/1.4765662.3
Three-dimensional plot of the dependence of evaporation velocities on evaporation area and e-beam intensity.
(a)–(e) Sequence TEM images of surface evaporation diffusion caused by pinning of the nanoparticles onto the surface, resulting in reshaping of the evaporation tips. Arrows indicate the position of the nanoparticle inclusions. This process is schematically shown in (f), where the dashed arrows indicate the change in the evaporation dynamics caused by pinning of the nanoparticles onto the surface. All TEM images have the same magnification; bar = 10 nm.
(a)–(h) Sequence TEM images of the slow evaporation of nanoparticle inclusions under Ie-beam ∼ 10 A cm−2, as indicated by arrows. All TEM images have the same magnification; bar = 20 nm. (i) Evaporation velocity normalized by the evaporation area for the SiO2 tip (open red rectangular) and the nanoparticle inclusions (open black circles). A dashed line is drawn to separate them, where the nanoparticle inclusions show slower evaporation velocity. Low values for the SiO2 tip at Iebeam ∼ 5 and 50 A cm−2 (indicated by dashed ellipses) were caused by simultaneously pinning several nanoparticles onto the surface, which blocked strongly their evaporation.
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