Local structure Al-Mn quasicrystals studied by EXAFS

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Abstract
The local structure around Mn atoms in icosahedral Al84Mn16 and in hexagonal Al4Mn is compared by means of EXAFS and XANES at the Mn edge. The Al4Mn crystalline phase has been selected as a possible reference structure since its composition corresponds closely to the actual composition of the icosahedral phase. The radial distribution functions are roughly similar in the two phases except for the skewness of the nearest-neighbour peak. A larger disorder beyond the first-neighbour shell causes the contribution from next nearest neighbours to be smeared in the quasicrystal, as compared with that in the hexagonal phase. The XANES spectra are identical, thus indicating similar point symmetry in the two phases.