PHASON RELATED STACKING DISORDER IN DECAGONAL AL-CO-NI

High-resolution transmission electron microscopy images of decagonal A l-Co-Ni quasicrystals are presented, which show the existence of phaso n related stacking disorder along the periodic tenfold axis. The image contrast in the interior of hexagon-shaped tiles shows an inner verte x only if no phason defect is present. This interpretation of the high -resolution micrographs is substantiated by electron microscopic image simulations based on a realistic structure model.