Characterization of the five-fold plane surface of an Al70.4Pd21.4Mn8.2 quasi-crystal by means of surface X-ray diffraction

The surface of a five-fold symmetry quasi-crystal of a thermodynamically st able icosahedral Al70.4Pd21.4Mn8.2 single grain has been studied by means o f X-ray diffraction. The calculated intensity reproduces rather well both t he Bragg peaks and surface signal. The fit of the measured structure factor shows a contraction of the outermost atomic layer. The system also tends t o be richer in Al and Pd, the atoms forming a very dense outer layer. (C) 1 999 Elsevier Science B.V. All rights reserved.