Solution of the average structure of decagonal Al_71.5Co_14.6Ni_13.9 by the ‘charge-flipping method’

Abstract

The average structure of the type-I modification of decagonal Al_71.5Co_14.6Ni_13.9 was solved by the five-dimensional (5D) ‘charge-flipping method’ based on a synchrotron diffraction data set with Laue symmetry 10/mmm and quasilattice parameters a_1–4 = 18.826(2) Å and a₅ = 4.0816(5) Å. Although the superstructure reflections constitute 4692 of all 7660 unique reflections they contribute to only 5.1% of the total integrated intensity. Their weight seems not to be sufficient for the charge-flipping algorithm to fully reconstruct the superstructure. Consequently, only a kind of averaged model will be discussed, based on two fundamental clusters with ≈20 Å diameter.

Acknowledgements

The authors thank Lukáš Palatinus for discussions about the algorithm and gratefully acknowledge financial support from the Swiss National Foundation under project SNF 200020-105158.