A pentagonal cluster in certain approximants to decagonal quasicrystals.

Area of Science:

• Materials Science
• Crystallography
• Condensed Matter Physics

Background:

• Quasicrystals exhibit unique atomic arrangements and properties.
• Approximants to quasicrystals share structural similarities and are crucial for understanding quasicrystal formation.
• Pentagonal clusters are recurring motifs in quasicrystal approximants.

Purpose of the Study:

• To describe a specific pentagonal cluster found in decagonal quasicrystal approximants.
• To elucidate the structural role and composition of this 'wheel cluster'.
• To identify the specific approximant structure types where this cluster is a primary component.

Main Methods:

• Structural analysis of quasicrystal approximants.
• Identification and characterization of the 'wheel cluster' motif.
• Comparison of cluster structure with known polyhedral assemblages.

Main Results:

• A pentagonal 'wheel cluster' motif, resembling a wheel with an axis and tyre, has been identified.
• This cluster is constructed from seven intergrown icosahedra.
• The 'wheel cluster' serves as a building block for infinite strands or nets in quasicrystal approximants, oriented perpendicular to the cluster's axis.
• The cluster is the main constituent in decagonal approximant structure types Al3Mn, Al60Mn11Ni4, and Ga137Mn123.

Conclusions:

• The identified 'wheel cluster' is a fundamental structural unit in specific decagonal quasicrystal approximants.
• Its unique icosahedral composition and arrangement dictate the formation of extended structures.
• Understanding this cluster provides insights into the atomic organization of quasicrystal approximants.