Abstract
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, constructed hierarchically by a kind of atomic cluster, are confirmed by experimental results of a high-resolution electron microscopy study and a single-crystal X-ray analysis. The structural models of the high-order approximants are constructed by periodically packing the subunits in unique ways. As an example, one of the high-order approximants is discussed in detail.