抄録
An order–disorder transformation in a single decagonal quasicrystal of Al72Ni20Co8 is studied in detail. In X-ray diffraction, the anomalous attenuation of intensities of Bragg reflections was found around the transformation temperature, Tc. The intensity attenuation at high temperature is explained by the anomalous Debye–Waller factor in thermal lattice dynamics. In particular, the intensity ratio above Tc and below Tc depends on |G|||2 values. In addition, the intensity ratio between room temperature and high temperature shows |G⊥|2 dependence. The results correspond to the in situ observation of a local vibrational anomaly related to an atomic flip by electron microscopy [Abe et al.: Nature 421 (2003) 347]. By X-ray diffraction, dynamic fluctuations as observed in electron microscopy are also realized even on a macroscopic scale at high temperature.
