Journal of Applied Crystallography

Volume 37, Part 5 (October 2004)

research papers

J. Appl. Cryst. (2004). 37, 802-807 [ doi:10.1107/S0021889804017820 ]

Disordered quasicrystals: diffuse scattering in decagonal Al-Ni-Fe

E. Weidner, F. Frey, J.-L. Lei, B. Pedersen, C. Paulmann and W. Morgenroth

Abstract: High-resolution synchrotron data of near-Bragg diffuse scattering from decagonal Al_71.5Ni_23.5Fe₅ quasicrystals were recorded. A dominant phasonic origin is ruled out because of the absence of a significant G dependence. An analysis solely in the frame of thermal diffuse scattering (TDS) theory (phonon scattering) showed a good match between experimental and calculated data in the quasiperiodic layers, but with an improbable ratio of elastic constants, c₆₆/c₁₁ = 4.0. In situ high-temperature measurements up to 1000 K revealed an increase of the intensity distribution perpendicular to the scattering vector G. Huang diffuse scattering (HDS) arising from quenched local defects has a general appearance that qualitatively reproduces the observed symmetry and anisotropy. An interpretation based on both TDS and HDS contributions is given.

Keywords: thermal diffuse scattering; Huang diffuse scattering; disorder; quasicrystals; phonon scattering; phason scattering.