STRUCTURAL MODELS OF HIGH-ORDER APPROXIMANTS OF THE AL-MN-PD DECAGONAL QUASI-CRYSTAL

Structural models of the high-order crystalline approximants of the Al -Mn-Pd decagonal quasicrystal are proposed. It is considered that the crystalline approximants are composed of the same kinds of subunits as those of the Al-Mn-Pd decagonal quasicrystal. The subunits, construct ed hierarchically by a kind of atomic cluster, are confirmed by experi mental results of a high-resolution electron microscopy study and a si ngle-crystal X-ray analysis. The structural models of the high-order a pproximants are constructed by periodically packing the subunits in un ique ways. As an example, one of the high-order approximants is discus sed in detail.