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Arrangement of Transition-Metal Atoms in an Approximant Crystal Related to Al–Cu–Co Decagonal Quasicrystals Studied by Cs-Corrected HAADF-STEM

  • K. YubutaEmail author
  • A. Yasuhara
  • K. Hiraga

Abstract

A crystalline approximant, which is related to Al–Cu–Co decagonal quasicrystals with two aperiodic planes stacking along the periodic axis, in an Al66Cu15Co19 alloy annealed at 900 C for 36 h has been studied by high-angle annular detector dark-field (HAADF) observations with Cs-corrected scanning electron microscopy (STEM). Observed HAADF-STEM images represent individual transition-metal (TM) atoms as bright dots, and so a three-dimensional arrangement of TM atoms in the approximant can be derived from the arrangement of bright dots. The structure has an orthorhombic unit cell with a 0=10.1 nm, b 0=0.4 nm and c 0=6.7 nm, formed by an ordered arrangement of two types of atom columnar clusters in a τ 3-inflated monoclinic Al13Co4 structure formed by a network of pentagons with an edge-length of 2 nm. The TM atoms in the two planes stacking along the b-axis are located at lattice points of a Penrose lattice with a bond length of 0.25 nm and pentagonal tilings with bond lengths of 0.47 and 0.76 nm.

Keywords

Atom Cluster Orthorhombic Unit Cell Decagonal Quasicrystal Decagonal Phase Mixed Site 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  1. 1.Institute for Materials ResearchTohoku UniversitySendaiJapan
  2. 2.EM Application GroupJEOL Ltd.TokyoJapan

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