Quasi-Unit-Cell Model for an Al-Ni-Co Ideal Quasicrystal based on Clusters with Broken Tenfold Symmetry

Abstract

We present new evidence supporting the quasi-unit-cell description of the ${\mathrm{Al}}_{72}{\mathrm{Ni}}_{20}{\mathrm{Co}}_8$ decagonal quasicrystal which shows that the solid is composed of repeating, overlapping decagonal cluster columns with broken tenfold symmetry. We propose an atomic model which gives a significantly improved fit to electron microscopy experiments compared to a previous proposal by us and to alternative proposals with tenfold symmetric clusters.