Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon
Abstract Experimental challenges in determining the phase diagram of carbon at temperatures and pressures near the graphite-diamond-liquid triple point are often related to the persistence of metastable crystalline or glassy phases, superheated crystals, or supercooled liquids. A deeper understandin...
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| Format: | Article |
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Nature Portfolio
2025-07-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-61674-5 |
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| author | Davide Donadio Margaret L. Berrens Wanyu Zhao Shunda Chen Tianshu Li |
| author_facet | Davide Donadio Margaret L. Berrens Wanyu Zhao Shunda Chen Tianshu Li |
| author_sort | Davide Donadio |
| collection | DOAJ |
| description | Abstract Experimental challenges in determining the phase diagram of carbon at temperatures and pressures near the graphite-diamond-liquid triple point are often related to the persistence of metastable crystalline or glassy phases, superheated crystals, or supercooled liquids. A deeper understanding of the crystallisation kinetics of diamond and graphite is crucial for effectively interpreting the outcomes of these experiments. Here, we reveal the microscopic mechanisms of diamond and graphite nucleation from liquid carbon through molecular simulations with first-principles machine learning potentials. Our simulations accurately reproduce the experimental phase diagram of carbon near the triple point and show that liquid carbon crystallises spontaneously upon cooling. Metastable graphite crystallises in the domain of diamond thermodynamic stability at pressures above the triple point. Furthermore, whereas diamond crystallises through a classical nucleation pathway, graphite follows a two-step process in which low-density fluctuations forego ordering. Calculations of the nucleation rates of the two competing phases confirm this result and reveal a manifestation of Ostwald’s step rule, where the strong metastability of graphite hinders the transformation to the stable diamond phase. Our results provide a key to interpreting melting and recrystallisation experiments and shed light on nucleation kinetics in polymorphic materials with deep metastable states. |
| format | Article |
| id | doaj-art-aa481eeff8af40ee809aedb9dbb4c2ec |
| institution | Kabale University |
| issn | 2041-1723 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Nature Communications |
| spelling | doaj-art-aa481eeff8af40ee809aedb9dbb4c2ec2025-08-20T03:43:10ZengNature PortfolioNature Communications2041-17232025-07-0116111010.1038/s41467-025-61674-5Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbonDavide Donadio0Margaret L. Berrens1Wanyu Zhao2Shunda Chen3Tianshu Li4Department of Chemistry, University of California DavisDepartment of Chemistry, University of California DavisDepartment of Civil and Environmental Engineering, George Washington UniversityDepartment of Civil and Environmental Engineering, George Washington UniversityDepartment of Civil and Environmental Engineering, George Washington UniversityAbstract Experimental challenges in determining the phase diagram of carbon at temperatures and pressures near the graphite-diamond-liquid triple point are often related to the persistence of metastable crystalline or glassy phases, superheated crystals, or supercooled liquids. A deeper understanding of the crystallisation kinetics of diamond and graphite is crucial for effectively interpreting the outcomes of these experiments. Here, we reveal the microscopic mechanisms of diamond and graphite nucleation from liquid carbon through molecular simulations with first-principles machine learning potentials. Our simulations accurately reproduce the experimental phase diagram of carbon near the triple point and show that liquid carbon crystallises spontaneously upon cooling. Metastable graphite crystallises in the domain of diamond thermodynamic stability at pressures above the triple point. Furthermore, whereas diamond crystallises through a classical nucleation pathway, graphite follows a two-step process in which low-density fluctuations forego ordering. Calculations of the nucleation rates of the two competing phases confirm this result and reveal a manifestation of Ostwald’s step rule, where the strong metastability of graphite hinders the transformation to the stable diamond phase. Our results provide a key to interpreting melting and recrystallisation experiments and shed light on nucleation kinetics in polymorphic materials with deep metastable states.https://doi.org/10.1038/s41467-025-61674-5 |
| spellingShingle | Davide Donadio Margaret L. Berrens Wanyu Zhao Shunda Chen Tianshu Li Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon Nature Communications |
| title | Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon |
| title_full | Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon |
| title_fullStr | Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon |
| title_full_unstemmed | Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon |
| title_short | Metastability and Ostwald step rule in the crystallisation of diamond and graphite from molten carbon |
| title_sort | metastability and ostwald step rule in the crystallisation of diamond and graphite from molten carbon |
| url | https://doi.org/10.1038/s41467-025-61674-5 |
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