A quasi-unit cell model for Al-Ni-Co Ideal Quasicrystal based on clusters with broken 10-fold symmetry

Abstract

We have constructed a structural solution for the $Al_{72}Ni_{20}Co_{8}$ decagonal quasicrystal based on the quasi-unit cell picture. The solution gives a significantly improved fit to experiments compared to a previous proposal by us while retaining the feature that the fundamental, repeating cluster has broken 10-fold symmetry. We present a series of arguments, including new evidence based on high-resolution transmission electron microscopy, which supports this solution over alternatives with 10-fold symmetric clusters.