Amorphous Nanomaterials. Lin Guo

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href="#ulink_07404e48-d5b4-57e8-a209-f61d9b127428">Figure 2.4 High signal-to-noise EEL spectrum acquired by the accumulating 1 s exposures while scanning repeatedly. The insets present a 50 frame average in false color from the stacks of images created during the acquisitions, showing clear threefold coordination (a) or fourfold coordination (b) of the Si atom. Source: Reproduced with permission from Ramasse et al. [61]. Copyright 2013, American Chemical Society.

      2.1.4 Applications in Amorphous Nanomaterial Characterization

      The recent progress of Cs-TEM provides a solid foundation to investigate the structures and compositions at the atomic level or in a complex environment with gas or liquid. This can then be integrated with energy-dispersive X-ray spectroscopy (EDS) and EELS techniques to observe the structure evolution of the materials and to investigate the mechanism of the composition changes. Notably, one achievement in the last few decades is the application of in situ TEM that involves various stimuli to nanomaterials with high-resolution imaging and spectroscopy. These stimuli may include heat, stress, electrical biasing, and ultrashort photon pulses to the materials. However, the high vacuum of TEM within the column to protect the electron gun and to avoid the electron scattering by gases and liquids makes it not compatible with gaseous or liquid environments. The development of environmental transmission electron microscopy (ETEM) has offered great chances to study the dynamic changes in materials with ultrahigh resolution in complex gaseous or liquid environments.

Schematic illustration of the in situ TEM experiments. (a) Schematics of structural evolution of bismuth to Na3Bi during electrochemical sodiation. (b) High‐resolution TEM image of a pristine bismuth flake. (c)‐(e) Time lapse TEM image of sodiation in bismuth.

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