Direct imaging of local chemical disorder and columnar vacancies in ideal decagonal al-ni-co quasicrystals

Atomic-resolution Z-contrast images provide direct images of chemical disorder and columnar vacancies in an ideal Al-Ni-Co decagonal quasicrystal. Chemical disorder occurs in the central ring of the 2 nm clusters and involves both Al and Ni(Co) atoms. Columnar vacancies are observed in the form of closely spaced, half-occupied atomic columns in specific rings within the clusters. This structure, derived from real space images, differs significantly from previous atomic models.