High Pressure Simulations on Diamond Formation from CaCO3 and H2 using First-Principles Molecular Dynamics
Abstract
Due to the long time for the natural formation of diamond, a lot of information of geochemical reactions and Earth movements can be revealed from the analysis of natural diamonds. Previously research have shown that diamond can be formed from alkaline carbonate melts[1][2][3], and that H2 can take an active part in the substance formation[4]. Hence, we assumed that CaCO3 and H2 can react to form diamond and water in the mantle and performed first-principles molecular dynamics (MD) to investigate its possibility. Two model structures of different stoichiometric ratios of CaCO3 and H2 were simulated at 40, 60, 80 and 120 GPa at high temperature corresponding to conditions at the upper and lower mantle. It was found that tetrahedral and diamond-like carbon formed readily at 80 and 120 GPa along with water. At 40 and 60 GPa the reactions are slower and the carbon preferred to maintain a planar structure. Much longer simulation is required to form the tetrahedral linking. The results show it is possible that diamond is formed from CaCO3 and H2 in the lower mantle.
References: [1] M. Chrenko, R. S. McDonald and K. A Darrow, Nature 214, 474-476 (1967). [2] N. Pal'yanov, V. S. Shatsky, N. V. Sobolev, A. G. Sokol. Proc Nat Acad Sci USA, 104: 9122-9127 (2007b). [3] N. Palyanov, A. G. Sokol. Lithos 112(S2):690-700 (2009). [4] Y. Hu, D. Y. Kim, W. Yang, L. Yang, Y. Meng, L. Zhang, and H. K. Mao, Nature (London) 534, 241-244 (2016).- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMMR23D0131K
- Keywords:
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- 3919 Equations of state;
- MINERAL PHYSICS;
- 3924 High-pressure behavior;
- MINERAL PHYSICS;
- 3939 Physical thermodynamics;
- MINERAL PHYSICS;
- 3994 Instruments and techniques;
- MINERAL PHYSICS