Electron Beam Etching of CaO Crystals Observed Atom by Atom

Abstract

With the rapid development of nanoscale structuring technology, the precision in the etching reaches the sub-10 nm scale today. However, with the ongoing development of nanofabrication the etching mechanisms with atomic precision still have to be understood in detail and improved. Here we observe, atom by atom, how preferential facets form in CaO crystals that are etched by an electron beam in an in situ high-resolution transmission electron microscope (HRTEM). An etching mechanism under electron beam irradiation is observed that is surprisingly similar to chemical etching and results in the formation of nanofacets. The observations also explain the dynamics of surface roughening. Our findings show how electron beam etching technology can be developed to ultimately realize tailoring of the facets of various crystalline materials with atomic precision.

Boosting the Long-Term Stability of Hydrotalcite-Derived Catalysts in Hydrogenolysis of Glycerol by Incorporation of Ca(II)

“…HRTEM images of the Co 2 -Ca 4 -Al 3 catalyst are shown in Figure c and d. The lattice spacing of 0.284 nm corresponding to {0 0 6} planes of CaCO 3 was clearly seen, in good agreement with the results of XRD (Figure e). Also, the lattice spacings of 0.176 and 0.277 nm attributed to the {2 0 0} planes of metallic Co 0 and {1 1 1} planes of CaO were also observed, respectively, , in line with the result of XRD (Figure e). It should be noted that although the CoAl 2 O 4 phase was proved by XRD and FT-IR characterizations (Figure and Figure S2), it was not observed from HRTEM probably due to its poor crystallinity.…”

In Situ Repair of 2D Chalcogenides under Electron Beam Irradiation

“…As reported previously, electron beam irradiation can induce sputtering and deposition simultaneously and these two processes may have different rates depending on the beam intensity . When the beam intensity is too high, the sputtering rate will be higher than the repair rate, and the material will be etched by the electron beam . On the contrary, when the beam intensity is too low, the repair rate will be lowered and it may take a very long time to repair, during which the cumulative effect of electron beam will cause damage as well .…”

Electron Beam Irradiation-Induced Deoxidation and Atomic Flattening on the Copper Surface

“…Different cases of nanostructural modifications by e-beam irradiation-induced effects, applied in transmission electron microscopy (TEM), have been reported on oxide materials (e.g., ZnO, CaO, and MgO) and two-dimensional (2D) materials (e.g., layered chalcogenides, ,, graphene, and graphite). Those structural evolutions were being proposed as a functional treatment for nanomaterial repair, nanostructural healing, and nanocrystal regrowth .…”

“…Today, the plasma-assisted ALE process, which is utilized for advanced etching with a high aspect ratio and three-dimensional geometries, 16 causes inestimable costefficiency for defect control. Therefore, to overcome the limitation, namely, removing a single atomic layer with damage prevention, researchers have gradually started paying attention to atomic surface manufacturing by e-beam irradiation effects (radiation damage, 17 knock-on effect, 18−21 mass sputtering, 22,23 and other atomic structure activation 24,25 Different cases of nanostructural modifications by e-beam irradiation-induced effects, applied in transmission electron microscopy (TEM), have been reported on oxide materials (e.g., ZnO, 24 CaO, 26 and MgO 27 ) and two-dimensional (2D) materials (e.g., layered chalcogenides, 21,25,28 graphene, 29 and graphite 30 ). Those structural evolutions were being proposed as a functional treatment for nanomaterial repair, 31 nanostructural healing, 27 and nanocrystal regrowth.…”