Structural characteristics of a high-quality Al-Ni-Ru decagonal quasicrystal with 1.6 nm periodicity, studied by atomic-scale electron microscopy observations

We report the structural characteristics of a high-quality stable decagonal quasicrystal (D phase) with 1.6 nm periodicity, formed in Al75Ni15Ru10 all oy annealed at 890 degreesC for 24 h. The tiling structure and the arrangem ent of transition-metal atoms (Ru and Ni) in this Al-Ni-Ru D phase have bee n clearly revealed by high-resolution electron microscopy (HREM) and by hig h-angle annular detector dark-held (HAADF) scanning transmission electron m icroscopy (STM) respectively. On the basis of the HREM and HAADF STM observ ations, the relationship between the arrangement of local structural units and the formation of the long-range quasiperiodic tiling structure is discu ssed.