Surface structure induced by Ar+-bombardment of decagonal AlNiCo
Journal of Alloys and Compounds 342(1-2): 437-440
We have investigated the surfaces of decagonal AlNiCo single quasicrystals in UHV by Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM) and Auger Electron Spectroscopy (AES). The surfaces were prepared by Ar+-sputtering and annealing. We observe well-defined RHEED patterns directly after sputtering at room temperature, revealing a ten-fold symmetry with respect to the azimuthal angle of the incident beam. Two patterns occur, alternating every 18°. This symmetry behaviour is probably caused by a bcc overlayer consisting of multiple domains in different orientations. The RHEED patterns show a strong temperature dependence. A spontaneous phase transition into a quasiperiodic structure is observed upon annealing to about 350 °C. RHEED patterns of a flat, quasicrystalline surface of good structural quality are observed after sputtering at 400 °C. As indicated by AES, the influence of oxygen on the structural behaviour seems to be important.