The crystalline structure of a 2/1 cubic approximant phase Al17Zn37Mg46 (Pa3, a=23.1 Å) for the Al-Zn-Mg icosahedral phase has been determined by the single crystal X-ray diffraction. The structure of the present 2/1 approximant is characterized by the packing of Bergman clusters and the atomic arrangements for six successive shells are similar to those found in the 1/1 cubic approximant. However, the fourth rhombicosidodecahedral shell of the 2/1 cubic approximant indicates a rather distorted figure together with the chemical disorder. This reflects the unique packing motif of the Bergman clusters in the 2/1 cubic approximant.
- Crystalline approximant
- Single-crystal X-ray diffraction
- Structural refinement