Local structure and symmetry elements of the decagonal quasicrystalAl70Co15

Abstract

Local real-space symmetry properties of the decagonal quasicrystal Al 70 Co 15 Ni 15 are determined using the secondary-electron imaging technique. A basic symmetry unit consisting of atoms on the vertices of tubelike stacked alternating pentagons and center-decorated decagons accounts for the observations.

Structural transformations at the surface of the decagonal quasicrystalAl70Co15NiZurkirch1, Bolliger2, Erbudak3 et al. 1998Phys. Rev. BSelf Cite423210View full textAdd to dashboardCite

“…1 and 2 and in those taken on a surface perpendicular to the twofold-symmetry axis. 6 the following relationship was found: A2P͉͉͗110͘ and A2D͉͉͗111͘ and ͗110͘. While this correspondence is accurate to within experimental error, 16 there is an expected mismatch of Ϯ0.75°between the A2D and the ͓111͔ directions.…”

“…By contrast, the experimental pattern completely overlaps with the projection of the quasicrystalline structure proposed recently. 6 To summarize, the decagonal surface of Al-Co-Ni has been observed to transform into a surface with cubic symmetry upon bombarding with Ar ϩ ions at room temperature. This transformation is caused by removing the Al atoms from the decagonal structure, thus resulting, with only a small lattice mismatch, in a bcc structure.…”

“…Secondary-electron imaging ͑SEI͒, on the other hand, is sensitive to the local order and can critically examine the short-range properties of the proposed models. 6 Shortly after the discovery of QC's, it was recognized that the structure of icosahedral Al-Mn undergoes a phase transition when exposed to irradiation with energetic particles. 7 Similar phenomena for decagonal QC's were reported after stable samples became available.…”

“…As a comprehensive description of this pattern has already been presented, 6 we only point out that a perfect decagonal structure has emerged at the surface. Moreover, the chemical composition equals the nominal bulk composition of Al 70 Co 15 Ni 15 , thus suggesting a segregation of Al atoms to the surface upon annealing.…”

Thin Sn film induced by surface diffusion on a quasiperiodic surface of decagonal Al–Ni–Co

“…Since Sn is immiscible with the elements in the substrate and has much a smaller surface energy than Au or Pt, we expected to form an SEQ film, if we chose a suitable condition for the film growth. So far, the quasicrystalline surface of the decagonal Al-NiCo has been investigated by several methods including secondary-electron imaging [6,7], reflection high-energy electron diffraction (RHEED) [8], scanning tunneling microscopy (STM) [9], spot profile analysis low energy electron diffraction (SPA-LEED) [10] and He scattering [11]. These studies show that the decagonal Al-Ni-Co phase has a bulk-terminated surface.…”