Encyclopedia of Glass Science, Technology, History, and Culture. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
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Жанр произведения: Техническая литература
Год издания: 0
isbn: 9781118799499
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in the lower panels, embedded into a silicon-rich matrix that isolates it from the actual yttrium-rich glass matrix."/>
Mg Al Si Zr Y
Nominal 16.5 33.9 41.4 4.2 4.0
EDXS pristine 16.8 33.7 41.1 4.5 3.9
EDXS annealed 11.8 17.2 43.1 2.7 25.2

      a Oxygen not considered because of self‐absorption of the low‐energy O‐K X‐rays.

      3.3 Electron Energy Loss Spectroscopy

      In analytical (S)TEM, an additional useful source of information concerns the nature, valence, and coordination of atoms, which affect specifically the energy loss undergone by the primary beam through inelastic scattering by electron clouds within the sample. As in X‐ray absorption spectroscopy (XAS) or, more precisely, X‐ray near‐edge structure spectroscopy (XANES) (see Chapter 2.2), the interaction of a given atom with its local environment, i.e. the influence of the nearest neighbors on its electronic structure, is thus probed with an appropriate spectrometer mounted below the sample, which filters electrons according to their energy loss. This energy loss near‐edge structure spectroscopy (ELNES) has certain advantages, such as a superior spatial resolution in comparison with XANES. In addition, it is applicable to light elements such as Li, Be, or B, whereas appropriate cross sections for X‐ray generation typically restricts EDXS to elements heavier than B. On the other hand, quantification of electron energy loss (EEL) spectra is not as straightforward as in EDXS, and one is restricted to energy losses lower than ≈2 keV with EELS. Thus, it complements nicely with EDXS, whose typical spectral domain for useful application starts at approximately 2 keV.

Graph depicts the Al-L2,3 edge EELS spectra of MAS sample areas that represent either the residual glassy part or the spinel therein.

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