The structure of a decagonal Al₇₂Ni₂₀Co₈quasicrystal

The structure of a decagonal Al₇₂Ni₂₀Co₈ quasicrystal with space group P10₅/mmc has been determined on the basis of a single-crystal X-ray data set using the five-dimensional description. The best-fit model structure based on a cluster model having lower symmetry than the decagonal symmetry with 103 parameters gives wR = 0.045 and R = 0.063 for 449 reflections. The structure is well described by the hexagon, boat and star tiling with an edge length of 6.36 Å and is very consistent with recent high-resolution electron-microscopy images. The refined structure is compared with previously discussed model structures including cluster-based models having 20 Å tenfold symmetric clusters.