High-resolution transmission electron microscopy lattice imaging

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. 

Lattice imaging by high resolution transmission electron microscopy (HRTEM) of fibrous manganese(IV) oxide minerals demonstrated the exis-... 

High-resolution transmission electron microscopy (HRTEM), using lattice imaging techniques, allows polytype analysis within single grains in the microstmcture of dense SiC bodies [20]. 

High resolution transmission electron microscopy (TEM) was further used to confirm the results described above. Figure 12.14 shows the TEM images of the catalyst after stable operation and after the aging stress test. While the catalyst after stable operation only shows the lattice fringes of anatase covered by a layer of amorphous vanadium oxide surface species, the stressed catalyst shows a more complex structure. The core of the support oxide particle still shows the lattice fringes of anatase, but lattice distances of rutile can be seen in a surface-near layer around... 

Figure 3 shows a high-resolution transmission electron microscopy (HR f EM) image of a typical boron nanowire. No ciystalline fringes can be identified in the HR f EM image at the lattice-resolved scale. This indicates that the boron nanowires are amorphous. No diffraction spots, but some diffuse rings, shown in the selected area electron diffraction (SAED) pattern [Fig. 3, inset] from the boron nanowire, further confirm the amorphous nature of the boron wires. The boron nanowire is sheathed by an amorphous oxide coating that is formed when the boron nanowires are exposed to air after deposition. The chemiced characterization of the boron nanowires using EELS shows that the boron nanowire is composed of boron with neglectable traces of oxygen [Fig. 4]. Quantitative EELS studies reveal that the total content of oxygen in the boron wire is less than 5%.

FIGURE 1.2 High-resolution transmission electron microscopy image of a supported Ru catalyst for ammonia synthesis recorded at 552°C and 5.2 mbar in a gas composition of 3 1 Hj/Nj. A Ru particle with a well-formed lattice and surface facets is seen on an amorphous support consisting of BN. A Ba-O promoter phase is observed on top of the Ru particle. Taken from Hansen et al. (2001) with permission from The American Association for the Advancement of Science. 

High resolution lattice images, obtained by transmission electron microscopy and shown in Figure 2, confirm the swelling of MCM-22 precursor and the generation of... 

The X-ray images of extended lattice imperfections within the crystal arise fi om variations in beam intensity caused by local distortions of the lattice. Dislocation densities of up to 10 mm can be resolved in transmission studies or ten times this by the reflection technique. This resolution is lower than that obtainable by transmission electron microscopy, but the sample used may be thicker and does not have to be examined under high vacuum. X-ray beams also produce less radiation damage in the sample. When decomposition proceeds beyond a > 0.01, distortion of the lattice is such that the X-ray image loses resolution and the exposures required become even longer. Reflection data obtained at several different diffraction angles may be required to characterize the imperfections present. 

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