Structure of Decagonal Al_<65>Cu_<20>Co_<15> Quasicrystals

A new model of the decagonal Al_Cu_Co_ quasicrystal has been proposed based on TEM images. This consists of large atom clusters proposed by Hiraga, Lincoln and Sun (Mater. Trans. JIM 32 (1991) 308) and used by Burkov (Phys. Rev. Lett. 67 (1991) 614) in his model. The arrangement of the atom clusters agrees with that shown by high-resolution electron microscopy. The model is compared with the Burkov model and the experimental result of X-ray diffraction by Steurer and Kuo (Acta Crystallogr. B46 (1990) 703). The present consideration suggests that the X-ray analysis based on 200-300 independent reflections is insufficient to determine the shape of atoms in the internal space accurately. A new method of the analysis using TEM images and more X-ray diffraction data is discussed