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Published on: June 12, 2019
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Polymorphic phase transition mechanism of compressed coesite.
11] Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China [2] School of Physics, Astronomy and Computational Sciences, George Mason University, Fairfax, Virginia 22030, USA [3] Geophysical Laboratory, Carnegie Institution of Washington, Washington, District Of Columbia 20015, USA.
Nature Communications
|March 21, 2015
Summary
Researchers discovered a new mechanism for silicon dioxide (SiO₂) phase transitions under high pressure. This finding clarifies pressure-induced amorphization and offers insights into densifying natural structures.
Area of Science:
- Geophysics and geochemistry
- Materials science
- Solid-state chemistry
Background:
- Silicon dioxide (SiO₂) is a ubiquitous compound with diverse polymorphic forms.
- Phase transitions in SiO₂ under pressure are of significant scientific interest.
- Understanding these transitions is crucial for geology and materials science.
Purpose of the Study:
- To investigate the polymorphic phase transition mechanism of coesite SiO₂ to post-stishovite.
- To explore the formation of intermediate phases during high-pressure compression.
- To elucidate the phenomenon of pressure-induced amorphization in SiO₂.
Main Methods:
- Single-crystal synchrotron X-ray diffraction experiments were performed on coesite SiO₂.
- Hydrostatic pressures ranging from 26-53 GPa were applied at room temperature.
- First-principles computational modeling was employed to support experimental findings.
Main Results:
- A novel phase transition pathway from coesite to post-stishovite was identified.
- Multiple previously unknown triclinic SiO₂ phases were observed as structural intermediates.
- Peak broadening and weakening in X-ray diffraction patterns indicated amorphization-like behavior.
Conclusions:
- The study reveals a new mechanism for SiO₂ phase transitions under extreme pressure.
- The findings provide critical insights into pressure-induced amorphization of SiO₂.
- This research enhances understanding of densification in tetrahedrally bonded structures.
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