Explanation of peak shapes observed in diffraction from icosahedral quasicrystals

Abstract
The distinctive peak shapes observed in diffraction studies of the icosahedral phases of Al-Mn, Al-Li-Cu, and related alloys are shown to arise from a specific configuration of quenched phason strains in a grain. This configuration is determined by considerations of symmetry and continuity of the phason field. Al-Mn and Al-Li-Cu peak shapes are explained by minor variations of a single mechanism.