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Modeling the phase diagram of carbon
Luca M Ghiringhelli1, Jan H Los, Evert Jan Meijer
1van 't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam, The Netherlands.
Physical Review Letters
|May 21, 2005
Summary
This study maps the phase diagram of diamond and graphite, confirming its accuracy with experimental data. Researchers ruled out a liquid-liquid phase transition in carbon, providing new estimates for diamond melting and triple points.
Area of Science:
- Materials Science
- Physical Chemistry
- Computational Physics
Background:
- Understanding carbon's phase diagram is crucial for materials science and high-pressure physics.
- Accurate phase boundaries inform predictions of carbon behavior under extreme conditions.
Purpose of the Study:
- To determine the phase diagram of diamond, graphite, and liquid carbon.
- To validate a new semiempirical potential for carbon simulations.
- To investigate the possibility of a liquid-liquid phase transition in carbon.
Main Methods:
- Utilized a recently developed semiempirical potential for carbon.
- Performed accurate free-energy calculations.
- Computed solid-solid and solid-liquid phase boundaries up to 400 GPa and 12 000 K.
Main Results:
- The computed graphite-diamond transition line aligns well with experimental data.
- The study provides accurate estimates for the diamond melting curve.
- The calculated slope of the graphite melting line refutes the existence of a liquid-liquid phase transition in carbon.
Conclusions:
- The employed semiempirical potential accurately models carbon's phase behavior.
- The existence of a liquid-liquid phase transition in carbon is unlikely under the studied conditions.
- This research refines our understanding of carbon's high-pressure, high-temperature phase diagram and triple points.