QUASICRYSTAL VERSUS TWINNED APPROXIMANT; A QUANTITATIVE ANALYSIS WITH DECAGONAL Al_(70)Co_(15)Ni_(15)

摘要

The techniques for analysing the structure of decagonal quasicrystals in five dimensions are applied to a five-fold twinned rational approximant. For conventional in-house diffraction facilities, a quantitative analysis for Al7oCoi5Nii5 shows, that the average structure and the local structure-building elements can be obtained nevertheless. The rationale for this approach to structure solution is given by the fact that the analysis of high resolution (e.g. synchrotron) X-ray diffraction data of high-order twinned approximants has not yet proceeded beyond mere metric considerations.