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A first-order liquid-liquid phase transition in phosphorus
1Department of Synchrotron Radiation Research, Japan Atomic Energy Research Institute, Sayo, Hyogo. katayama@spring8.or.jp
Nature
|January 26, 2000
Summary
First-order liquid-liquid phase transitions are rare but observed in phosphorus. Pressure induces a rapid, reversible structural change between molecular and polymeric liquid forms, indicating a novel phase transition.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Physical Chemistry
Background:
- First-order structural phase transitions are common in solids.
- First-order liquid-liquid phase transitions in pure substances are exceptionally rare.
- Previous studies suggested such transitions in supercooled water and liquid carbon.
Purpose of the Study:
- To investigate the possibility of a liquid-liquid phase transition in phosphorus.
- To observe the structural changes in liquid phosphorus under varying pressure conditions.
Main Methods:
- In situ X-ray diffraction was employed to study liquid phosphorus.
- Experiments were conducted under varying pressure conditions, specifically above 1 GPa.
Main Results:
- A pressure-induced structural transformation in liquid phosphorus was observed.
- Two distinct liquid forms were identified: a low-pressure molecular form (P4) and a high-pressure polymeric form.
- The transformation between these forms is sharp, rapid, reversible, and occurs over a narrow pressure range (<0.02 GPa).
- Coexistence of both liquid forms during the transition was noted.
Conclusions:
- The observed phenomena in liquid phosphorus strongly suggest a first-order liquid-liquid phase transition.
- This finding provides new insights into the behavior of matter in the liquid state under extreme conditions.
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