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Temperature-induced phase transitions in the rock-salt type SiC: a first-principles study
V I Ivashchenko1, P E A Turchi2, Leonid Gorb3,4
1Institute for Problems of Material Science, NAS of Ukraine, Krzhyzhanovsky str. 3, 03142 Kyiv, Ukraine.
Summary
First-principles simulations reveal how rock-salt silicon carbide (B1-SiC) transforms into various polytypes upon decompression. These pathways depend on phonon modes and initial conditions, offering insights into material phase transitions.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Computational Chemistry
Background:
- Silicon carbide (SiC) exhibits diverse polytypes with unique properties.
- Understanding phase transitions under pressure is crucial for materials design.
Purpose of the Study:
- To investigate the decompression-induced phase transitions of rock-salt SiC (B1-SiC).
- To elucidate the transformation pathways and identify intermediate structures.
Main Methods:
- First-principles molecular dynamics simulations.
- Analysis of symmetry and phonon spectra of transient structures.
- Tracking atomic displacements and lattice strains.
Main Results:
- Identified plausible transformation pathways of B1-SiC to 3C-, 2H-, 4H-, and 12R-SiC polytypes.
- Demonstrated that decompression leads to phonon mode condensation and intermediate states.
- Observed that decompressed structures can be recompressed under high pressure (120-250 GPa).
Conclusions:
- Decompression pathways are governed by soft phonon modes and simulation initial conditions.
- The study proposes a framework for identifying structural transformation paths in similar materials.
- This research contributes to the fundamental understanding of SiC polymorphism.
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