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AsS melt under pressure: one substance, three liquids
V V Brazhkin1, Y Katayama, M V Kondrin
1Institute for High Pressure Physics, Russian Academy of Sciences, 142190, Troitsk Moscow region, Russia.
Physical Review Letters
|June 4, 2008
Summary
This study reveals two key transformations in liquid arsenic sulfide (AsS) under high pressure. These transitions alter its viscosity and metallic properties, impacting its phase behavior and glass formation.
Area of Science:
- Materials Science
- High-Pressure Physics
- Condensed Matter Physics
Background:
- Understanding the behavior of chalcogenide materials like arsenic sulfide (AsS) under extreme conditions is crucial for developing new materials.
- Previous studies have explored the crystalline phases of AsS, but its liquid-state behavior under pressure remains less understood.
Purpose of the Study:
- To investigate the in situ high-temperature and high-pressure phase transitions of liquid arsenic sulfide (AsS).
- To characterize the structural and property changes occurring in AsS melt under compression.
- To explore the glass-forming ability of AsS from different liquid states.
Main Methods:
- In situ high-temperature and high-pressure experiments utilizing X-ray diffraction.
- Electrical resistivity measurements to probe changes in conductivity.
- Quenching from the melt to preserve high-pressure phases and study glass formation.
Main Results:
- Direct evidence for two distinct phase transitions in liquid AsS under compression.
- Transition 1 (1.6–2.2 GPa): Moderate-viscosity molecular liquid transforms into a high-viscosity, nonmetallic polymerized liquid.
- Transition 2 (4.6–4.8 GPa): Polymerized liquid converts to a low-viscosity metallic liquid.
- Rapid cooling of the molecular and metallic liquids yields crystalline phases, while the polymerized liquid readily forms a new AsS glass.
Conclusions:
- Liquid AsS exhibits complex phase transitions under pressure, transitioning between molecular, polymerized, and metallic states.
- The observed transitions are linked to significant changes in viscosity and electronic properties.
- The polymerized liquid state is key to forming AsS glass, offering insights into chalcogenide glass design.
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