Full real-space analysis of a dodecagonal quasicrystal

Area of Science:

• Materials Science
• Surface Science
• Crystallography

Background:

• Quasicrystals exhibit long-range order without translational periodicity.
• Dodecagonal quasicrystals possess twelve-fold rotational symmetry.
• Understanding atomic structure is key to quasicrystal properties.

Purpose of the Study:

• Determine the atomically resolved real-space structure of a dodecagonal oxide quasicrystal.
• Compare experimental atomic positions with theoretical tiling models.
• Investigate symmetry reduction and its origins.

Main Methods:

• Scanning tunnelling microscopy (STM) was used to image the quasicrystal surface.
• Atomic positions were precisely determined from STM data.
• Experimental tiling element frequencies and orientations were analyzed.

Main Results:

• 8100 atomic positions of a BaTiO3-derived oxide quasicrystal on Pt(111) were mapped.
• Experimental tiling element abundances closely matched the ideal Niizeki-Gähler model.
• Local symmetry reduction from dodecagonal to sixfold was observed, attributed to substrate interaction.

Conclusions:

• The study provides a detailed atomic-level view of a dodecagonal quasicrystal.
• Experimental results validate theoretical tiling models for quasicrystals.
• Substrate interactions can induce local symmetry changes while preserving long-range order.