Insight into the structure of decagonite - the extraterrestrial decagonal quasicrystal

Area of Science:

• Materials Science
• Mineralogy
• Crystallography

Background:

• Decagonite (Al₇₁Ni₂₄Fe₅) is the sole known natural decagonal quasicrystal.
• It was discovered in a meteorite dating to the early Solar System.
• Understanding its structure provides insights into quasicrystal formation in extraterrestrial environments.

Purpose of the Study:

• To determine the first structural model of natural decagonite.
• To compare its structure with synthetic decagonal quasicrystals.
• To investigate the perfection and formation conditions of natural quasicrystals.

Main Methods:

• X-ray diffraction analysis of a decagonite fragment.
• Development of a structural model based on the collected data.
• Comparative analysis with existing models of synthetic quasicrystals.

Main Results:

• A two-layer structural model for decagonite was established.
• Decagonite features decagonal columnar clusters arranged in a pentagonal Penrose tiling.
• The natural quasicrystal exhibits low linear phason strain and high structural perfection.

Conclusions:

• The structural model of decagonite presents unique characteristics compared to synthetic counterparts.
• Decagonite's high perfection suggests formation under conditions distinct from laboratory synthesis.
• This study advances the understanding of natural quasicrystal formation and properties.