Local structure at Mn sites in icosahedral Mn-Al quasicrystals

Extended X-ray-absorption fine-structure measurements have been made at the Mn K edge of quasicrystalline and crystalline forms of an Al6Mn alloy. Two different quasicrystalline Mn sites are discerned to be populated in the ratio of tau, the golden mean, within experimental error. The more populous site is similar to that in the crystal but with bond-angle distortions and elimination of an unusually short Al-Mn bond, while the other site has additional bond-stretching distortions. The measurements together with density measurements indicate that the volume per Mn site is independent of the type of site. (Author)