The structure of an Al-Ni-Co pentagonal quasicrystal studied by high-angleannular detector dark-field electron microscopy

An Al-Ni-Co pentagonal quasicrystal, showing electron diffraction patterns with pentagonal symmetry and including so-called superlattice reflections, has been examined by the high-angle annular detector dark-field technique w ith scanning transmission electron microscopy. Columnar clusters with penta gonal arrangement of transition-metal atoms around their centres are arraye d in a rhombic tiling with a bond length of 2 nm, all the clusters having t he same orientation of pentagonal symmetry.