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Identification of the kinematical forbidden reflections from precession electron diffraction

Published online by Cambridge University Press:  31 January 2011

Jean-Paul Morniroli  and
Gang Ji
Jean-Paul Morniroli
Affiliation:
[email protected], Laboratoire de Métallurgie Physique et Génie des Matériaux, UMR CNRS 8517, Villeneuve d’Ascq, France
Gang Ji
Affiliation:
[email protected], Laboratoire de Métallurgie Physique et Génie des Matériaux, UMR CNRS 8517, Villeneuve d’Ascq, France
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Abstract

The visibility of the kinematical forbidden reflections due to glide planes, screw axes and Wyckoff positions is considered both on experimental and theoretical electron precession patterns as a function of the precession angle. The forbidden reflections due to glide planes and screw axes become very weak and disappear at large precession angle so that they can be distinguished from the allowed reflections and used to deduce the space groups. Contrarily, those due to Wyckoff positions remain visible and strong provided they are located on a major systematic row. This difference of behavior between the forbidden reflections is confirmed by observation of the corresponding dark-field LACBED patterns and is interpreted using the Ewald sphere and the Laue circles from the availability of double diffraction paths. This study also proves that dynamical interactions remain strong along the main systematic rows present on precession patterns.

Keywords

crystallographic structuretransmission electron microscopy (TEM)Si
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1184: Symposium GG – Electron Crystallography for Materials Research and Quantitive Characterization of Nanostructured Materials , 2009 , 1184-GG01-03
Copyright
Copyright © Materials Research Society 2009

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