Publication Date:
1999-03-01
Description:
The electron microscope provides an ideal environment for the structural analysis of small volumes of amorphous and polycrystalline materials by enabling the collection of scattering information as a function of energy loss and momentum transfer. The scattered intensity at zero energy loss can be readily processed to a reduced density function, providing information on nearest-neighbour distances and bond angles. A method for collecting and processing the scattered intensity, which allows for the collection of an energy-loss spectrum for a range of momentum transfers, is discussed. A detailed structural determination from a reduced density function alone is difficult and it is shown that a more detailed structural model can be obtained by combining the experimental reduced density function with model structures obtained from molecular dynamics based on first-principles quantum mechanics. This method is applied to tetrahedral amorphous carbon, as an example of a monatomic network, and to aluminium nitride, as a prototype for a binary amorphous alloy.
Print ISSN:
0108-7673
Electronic ISSN:
2053-2733
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
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