Imaging in TEM

Ishizuka, K. Contrast transfer of crystal images in TEM. Ultramicroscopy 1980, 5, 55-65. 

HAADF High angle angular dark field (imaging in TEM)... 

Fig. 1. (a) Geometrical relationship between incident electron beams in TEM and CNT, (b) typical TED pattern, (e) schematic illustration of image of CNT and (d) ero.ss-seetional view of CNT. In the TED pattern, the indexes follow those of graphite. 

Figure 5 shows a ray path in TEM equipped with a Castaing-Henry imaging filter lens (Zeiss CEM-902). The imaging filter lens consists of a double magnetic prism and an electrostatic mirror. There is a limitation to accelerating... 

FIGURE 19.7 Visualization of network stmctures of carbon black in natural mbber (NR) matrix by skeletonization of tbe three-dimensional-transmission electron microscopic (3D-TEM) images, (a) CB-10 (b) and (d), CB (c) CB-80. The image in (d) shows the expanded one from the network skeleton of CB-40. The white bar for each direction shows the distance of 100 nm. (From Kohjiya, S., Kato, A., Suda, T., Shimanuki, 1., and Ikeda, Y., Polymer, Al, 3298, 2006. With permission.)... 

Dedicated SEM instruments have a resolution of about 5 nm. The main difference between SEM and TEM is that SEM sees contrast due to the topology and composition of a surface, whereas the electron beam in TEM projects all information on the mass it encounters in a two-dimensional image, which, however, is of subnanometer resolution. 

Overall platelet dimensions of mineral aurichalcite did not appear to change during calcination, but became polycrystalline and porous. By dark field Imaging in the TEM, the ZnO particles were observed to be uniformly and highly dispersed. The porosity can be accounted for by the approximately threefold increase in density of Zn atoms upon decomposition of aurichalcite to ZnO. For this density change to occur with a constant overall platelet volume, pores must form. 

It is noteworthy that the HRTEM cannot distinguish core and shell even by combining X-ray or electron diffraction techniques for some small nanoparticles. If the shell epitaxially grows on the core in the case of two kinds of metals with same crystal type and little difference of lattice constant, the precise structure of the bimetallic nanoparticles cannot be well characterized by the present technique. Hodak et al. [153] investigated Au-core/Ag-shell or Ag-core/Au-shell bimetallic nanoparticles. They confirmed that Au shell forms on Ag core by the epitaxial growth. In the TEM observations, the core/shell structures of Ag/Au nanoparticles are not clear even in the HRTEM images in this case (Figure 7). 

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