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Détermination des indices hkl en rayonnement polychromatique par la méthode des marqueurs de longueurs d'onde. Application à l'étude de structures modulées
Author(s) -
Marmeggi J.C.
Publication year - 1984
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889884011511
Subject(s) - reciprocal lattice , physics , diffractometer , optics , diffraction , detector , crystal (programming language) , wavelength , neutron , orientation (vector space) , geometry , nuclear physics , mathematics , scanning electron microscope , computer science , programming language
In the conventional Laue method with a stationary crystal only the ratios h : k : l of the reciprocal‐space point coordinates can be obtained for a crystal of known cell and orientation. A new method is described which determines the values hkl themselves. This result is obtained by slightly rotating the crystal in a polychromatic beam and by using simultaneously `wavelength markers' in a photographic recording. The method is particularly useful in the study of modulated structures where it can determine the amplitudes and directions of wavevectors k and their variation under the influence of external parameters such as temperature, pressure, applied fields. The method is general; it can be applied to neutrons as well as X‐rays. The outlines of the corresponding experiments are proposed in the paper. By directly giving the wavevectors k , it provides valuable guide lines for the collection of intensities on a conventional four‐circle diffractometer with a single detector. The `marker method' is here applied to the study of α‐U by neutron diffraction.