Quasi-unit-cell model for an Al-Ni-Co ideal quasicrystal based on clusterswith broken tenfold symmetry

We present new evidence supporting the quasi-unit-cell description of the A l72Ni20Co8 decagonal quasicrystal which shows that the solid is composed of repeating, overlapping decagonal cluster columns with broken tenfold symme try. 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.