Structure of an icosahedral Al-Mn quasicrystal

Abstract

A structure model of an icosahedral Al-Mn quasicrystal is proposed based on the structure-factor calculation and the x-ray and neutron powder-diffraction patterns of rapidly solidified Al-Mn alloys. The model has a local atomic arrangement similar to that of the cubic \ensuremath{\alpha}--Al-Mn-Si and has icosahedral point symmetry. To derive the model six-dimensional description of the three-dimensional Penrose lattice is extended to more general quasicrystals. The model explains the x-ray and neutron diffraction intensity, chemical composition, and density of the icosahedral quasicrystal.