High-resolution fringe-image electron

Figure 2.6. High-resolution fringe-image electron micrographs of structure in different carbons, (a) Single-crystal graphite showing parallelism of layers, (b) A partially graphitized carbon from PVC (1573 K). (c) A non-graphitizable carbon from PVDC (2973 K).

Chemical Modifications to Pitch. The earlier attempts to improve the commercial value of pitch residues must have been essentially exploratory research. Sanada et al, (71) in 1973 methylated the hydroxyl groups of 3,5-dimethyl phenol formaldehyde resin and noted, on carbonization, the formation of spheres of mesophase, the original resin giving an optical texture of mosaics in resultant carbons. Mochida et al. (72) carbonized naphthalene, anthracene and pyrene with aluminium chloride, sodium and potassium and examined the structure of the resultant carbons by optical microscopy and high resolution, fringe-imaging transmission electron microscopy (TEM),... 

Images Using High-Resolution, Fringe-imaging Transmission Electron Microscopy, Marsh et al. (1982), Figure 3.21 (a c)... 

The length and the diameter of MWCNT can be measured directly by TEM. From high-resolution transmission electron microscopy (HRTEM) images exhibiting oo.l fringes follows the number of coaxial tubes and possibly the microstructure of the caps in MWCNT, as viewed along the incident electron beam [24], Also anomalous intercylinder spacings and defects are revealed in this way [1,11]. 

High Resolution Transmission Electron Microscopy (HRTEM, Philips CM20, 200 kV) was applied to get structural and nanotextural information on the fibers, by imaging the profile of the aromatic carbon layers in the 002-lattice fringe mode. A carbon fiber coated with pyrolytic carbon was incorporated in epoxy resin and a transverse section obtained by ultramicrotomy was deposited on a holey carbon film. An in-house made image analysis procedure was used to get quantitative data on the composite. 

FIGURE 15.1 High-resolution transmission electron microscopy images of CNTs. (a) SWNT (b) MWNT (c) closed MWNT tips (MWNT tips) and (d) closed SWNT tip. The separation between the closely spaced fringes in the MWNT (b, c) is 0.34 nm, close to the spacing between graphite planes. The diameter of the SWNT (a, d) is 1.2nm. (Reprinted with permission from [8]. Copyright (1999) American Chemical... 

Fortunately, the images obtained at high resolution do not provide only the projected contours of the microcrystals. When one or more crystal planes are parallel to the electron beam, plane fringes are observed in the micrograph which are superimposed on the 2D projection of the microcrystal. 

Chems et al [18] performed a detailed quantitative analysis of CBED data for (1010) inversion domains in GaN grown on sapphire and concluded that of the various structural models tested, only the IDB model [14] was consistent with their data. High resolution electron microscopy images [16,20] also support the IDB model. Such images show a shift in intensity of lattice fringes across the (1010) plane that is consistent with the proposed model. 

Figure 9.16 High-resolution electron microscope images of carbon nanotubes first observed by Iijima (the fringes in the figure represent the walls of the carbon nanotubes). Reproduced with permission from [98], Copyright (1991) Nature Publishing...

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