5-DIMENSIONAL STRUCTURE REFINEMENT OF DECAGONAL AL78MN22

A single-crystal x-ray structure analysis of the metastable decagonal phase Al78(2)Mn22(2), centrosymmetric superspace group P10(5)/mmc, has been performed using the n-dimensional (n-D) approach. The structure has been solved by Patterson analysis and subsequent least-squares refinement, both in the 5D description. The final wR = 0.144 for 233 independent reflections with I > 2-sigma-(I) and 18 variables. There are four 5D atoms in the asymmetric unit generating one planar and one strongly puckered quasiperiodic atomic layer in physical space. These layers show close resemblance to the respective planar and puckered layers of the crystalline Al13Fe4 phase. The 3D decagonal structure is built of periodically stacked packings of six such layers per translation period.