Asymmetric pentagonal cluster on an Al–Cu–Co quasicrystal surface

Abstract

The 10-fold surface of a decagonal Al₆₆Cu₁₇Co₁₇ quasicrystal has been studied by scanning tunneling microscopy (STM). Three kinds of characteristic pentagonal clusters are observed in the STM images. Clusters within a given terrace have the same orientation, while those in adjacent terraces have opposite orientations. We show that two of the pentagonal cluster types are part of the 2-nm cluster, which is considered to be the basic structural unit of the Al–Cu–Co quasicrystal. The local atomic arrangement in the 2-nm clusters is found to be asymmetric.

Keywords:

• Al–Cu–Co
• quasicrystals
• structure analysis
• surface analysis
• cluster-assembled materials
• scanning probe microscopy

Acknowledgement

The authors gratefully acknowledge T. Sumi in the machine workshop at the School of Engineering, Nagoya University, for technical assistance.