Surface structure and structural transition of decagonal Al-Ni-Co quasicrystal

X-ray photoelectron diffraction (XPD) and reflection high-energy electron d iffraction (RHEED) measurements have been performed to investigate the surf ace structure of the decagonal Al72Ni12Co16 quasicrystal, which is known as a two dimensional quasicrystal. RHEED patterns for the surface parallel to the quasiperiodic planes are almost identical to the selected area electro n diffraction (SAD) patterns taken along the twofold axes of the bulk sampl e. The XPD images show clear tenfold-symmetric patterns consistent with the long range orientational order of the decagonal quasicrystal. These facts suggest that the surface has the same quasiperiodic structure as in the bul k. The surface phase transition induced by Ar+ ion bombardment is also inve stigated. (C) 2000 Elsevier Science B.V. All rights reserved.