J. Phys. I France
Volume 3, Numéro 9, September 1993
Page(s) 1953 - 1968
DOI: 10.1051/jp1:1993223
J. Phys. I France 3 (1993) 1953-1968

Single crystal X-ray study of a modulated icosahedral AlCuFe phase

N. Menguy1, M. de Boissieu1, P. Guyot1, M. Audier1, E. Elkaim2 and J. P. Lauriat2

1  Laboratoire de Thermodynamique et Physico-Chimie Métallurgiques, Domaine Universitaire, B.P. 75, 38402 St Martin d'Hères Cedex, France
2  LURE/CNRS/CEA/MEN, Bât. 209 D, 91405 Orsay Cedex, France

(Recceived 2 February 1993, revised 20 April 1993, accepted 28 May 1993)

A single grain of a modulated icosahedral AlCuFe phase has been studied by X-ray diffraction using the synchrotron light source at LURE (Laboratoire pour I'Utilisation du Rayonnement Electromagnétique, Orsay, France), Each main icosahedral reflection is flanked by twelve satellites along fivefold directions. The integrated intensity of 22 reflections and of their satellites have been measured in a broad $G_{\parallel}$ and $G_{\perp}$ range. Despite the presence of the satellites the overall icosahedral symmetry is maintained. The results are interpreted on the basis of six independent displacive cosine waves, propagating along the fivefold axes of the 6-dim periodic space. The polarization of these cosine waves is found to be longitudinal with a main component in perpendicular space which means that the modulation is of "phason" origin.

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