Structural complexity in ramp-compressed sodium to 480 GPa.
Danae N Polsin1,2, Amy Lazicki3, Xuchen Gong4,5
1University of Rochester Laboratory for Laser Energetics, Rochester, NY, USA. dpol@lle.rochester.edu.
Nature Communications
|May 9, 2022
Summary
Extreme pressure transforms sodium into an electride by squeezing electrons into voids, causing melting and recrystallization. This reveals novel, temperature-driven phases stabilized by core electron overlap.
Area of Science:
- Condensed Matter Physics
- Materials Science
- High-Pressure Physics
Background:
- Material properties are dictated by valence electron configurations at ambient pressure.
- Extreme pressures cause core-electron orbital overlap, predicting novel quantum behaviors.
Purpose of the Study:
- To investigate the behavior of elemental sodium under extreme compression.
- To explore the potential formation of electride phases in sodium at high pressures.
Main Methods:
- Ramp compression of sodium to nearly 500 GPa.
- In situ x-ray diffraction for phase transition analysis.
- Optical reflectivity measurements to study electronic properties.
Main Results:
- Density increased 7-fold, reducing interatomic distance and squeezing valence electrons.
- Pressure-induced melting and recrystallization occurred rapidly.
- Observed unexpected phase transitions and a precipitous decrease in optical reflectivity.
- Evidence suggests the formation of electride states due to core electron overlap.
Conclusions:
- Extreme compression induces significant structural and electronic changes in sodium.
- Core electron overlap under high pressure stabilizes unique electride phases.
- Discovered temperature-driven polymorphism in compressed sodium.
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