Acta Crystallographica Section A

Foundations of Crystallography

Volume 58, Part 4 (July 2002)

research papers

Acta Cryst. (2002). A58, 385-390 [ doi:10.1107/S0108767302007985 ]

Absolute structure-factor measurements of an Al-Pd-Mn quasicrystal

Y. Zhang, R. Colella, S. Kycia and A. I. Goldman

Abstract: A number of X-ray reflections from an icosahedral quasicrystal Al-Pd-Mn have been measured with great accuracy on an absolute basis by making use of Bragg-case diffraction. Since the specimen had high crystal quality, the dynamical theory was used for analyzing the results and to extract structure factors from measured integrated intensities. Good agreement was found between theory and experiment for strong reflections. Anomalous transmission was found to be strong in the `good' regions of the quasicrystalline specimen and it was measured on an absolute basis, but the small residual strains present in the specimen prevented an accurate comparison between theory and experiment. A detailed discussion is presented on the parameters that mostly affect anomalous transmission in relationship to the adopted structural model.

Keywords: quasicrystals; structure factors; anomalous transmission; dynamical theory.