Chemical disorder and columnar vacancies in ideal decagonal Al-Ni-Co quasicrystals

Yanfa Yan, S. J. Pennycook, A. P. Tsai

Research output: Contribution to journalConference articlepeer-review


Atomic-resolution Z-contrast images provide conclusive evidence for chemical disorder in an ideal Al-Ni-Co quasicrystal. The so-called basic Ni-rich, high-temperature, quasiperiodic structure exhibits chemical disorder at the center of the 2 nm diameter clusters that involves both the Al and Ni(Co) atoms. The atomic structure of the 2 nm clusters is derived directly from the images and differs from previous models. The presence of closely-spaced, half-occupied atomic columns (or columnar vacancies) in specific rings within the clusters is directly observed. We propose that these columnar vacancies mediate the phason flips necessary for transformation to random tiling.

Original languageEnglish
Pages (from-to)189-194
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Publication statusPublished - 1999 Jan 1
Externally publishedYes
EventProceedings of the 1998 MRS Fall Meeting - The Symposium 'Advanced Catalytic Materials-1998' - Boston, MA, USA
Duration: 1998 Nov 301998 Dec 3

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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