Diamond formation from hydrocarbon mixtures in planets
Bingqing Cheng, Sebastien Hamel, Mandy Bethkenhagen
Hydrocarbon mixtures are extremely abundant in the Universe, and diamond formation from them can play a crucial role in shaping the interior structure and evolution of planets. With first-principles accuracy, we first estimate the diamond nucleation rate in pure liquid carbon, and then reveal the nature of chemical bonding in hydrocarbons at extreme conditions. We finally establish the pressure-temperature phase boundary where diamond can form from hydrocarbon mixtures with different atomic fractions of carbon. Notably, we find a depletion zone in Neptune (but not Uranus) where diamond formation is thermodynamically favorable regardless of the carbon atomic fraction, due to a phase separation mechanism. These findings can lead to a better understanding of the physics of planetary formation and evolution, and help explain the low luminosity of Uranus.
Subjects: Materials Science (cond-mat.mtrl-sci); Earth and Planetary Astrophysics (astro-ph.EP); Computational Physics (physics.comp-ph)
Cite as: arXiv:2207.02927 [cond-mat.mtrl-sci] (or arXiv:2207.02927v1 [cond-mat.mtrl-sci] for this version)
https://doi.org/10.48550/arXiv.2207.02927
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Submission history
From: Bingqing Cheng
[v1] Wed, 6 Jul 2022 19:07:14 UTC (1,928 KB)
