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X-Ray Diffraction of Ramp-Compressed Silicon to 390 GPa
X Gong1,2, D N Polsin1,2, R Paul1,2
1University of Rochester Laboratory for Laser Energetics, Rochester, New York 14623-1299, USA.
Physical Review Letters
|March 3, 2023
Summary
This study reveals new crystal structures of silicon (Si) under extreme pressure. Silicon forms hexagonal close-packed and face-centered cubic structures at high pressures, extending known stability ranges.
Area of Science:
- Materials Science
- Condensed Matter Physics
- High-Pressure Physics
Background:
- Silicon (Si) undergoes various phase transitions under compression.
- Understanding these transitions is crucial for materials science and geophysics.
Purpose of the Study:
- To investigate the crystal structure of silicon under ramp compression.
- To determine the phase boundaries and structural stability of Si at high pressures.
Main Methods:
- In situ diffraction measurements using angle-dispersive X-ray scattering.
- Ramp compression of silicon samples to pressures between 40 and 389 GPa.
Main Results:
- Silicon (Si) was observed to form a hexagonal close-packed (hcp) structure between 40 and 93 GPa.
- At higher pressures, Si transitioned to a face-centered cubic (fcc) structure, stable up to 389 GPa.
- The stability range of the hcp phase extended beyond theoretical predictions.
Conclusions:
- The study provides new insights into the high-pressure behavior of silicon.
- Experimental results challenge existing theoretical models for Si phase transitions.
- Identified crystal structures advance the understanding of materials under extreme conditions.
