Dynamical phasons in a perfect quasicrystal

Abstract

The temperature dependence of x-ray peak intensities of icosahedral AlCuFe is studied in detail. Above 670°C, measurements of the Debye-Waller factor suggest the presence of dynamical phasons. Softening of the phason modes drives a structural transition at 1/4670°C below which the quasicrystal decomposes into coherent micrograins of a lower-symmetry phase. Implications for quasicrystal stability are discussed. © 1989 The American Physical Society.