Hydrogenation of calcite and change in chemical bonding at high pressure: Diamond formation above 100GPa

Journal Article · Tue Jul 09 00:00:00 EDT 2024 · Physics of the Earth and Planetary Interiors

DOI:https://doi.org/10.1016/j.pepi.2024.107228· OSTI ID:2569851

Goncharov, Alexander F. ^[1]; Kuang, Huiyao ^[2]; Tse, John S. ^[2]; Edmund, Eric ^[1]; Bykov, Maxim ^[3]; Bykova, Elena ^[4]; Chariton, Stella ^[5]; Prakapenka, Vitali B. ^[5]; Fedotenko, Timofey ^[6]; Giordano, Nico ^[6]; Mezouar, Mohamed ^[7]; Smith, Jesse S. ^[8]

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1. Carnegie Inst. of Science, Washington, DC (United States)
2. Univ. of Saskatchewan, Saskatoon, SK (Canada)
3. Univ. of Cologne (Germany); Johann Wolfgang Goethe Universität Frankfurt (Germany)
4. Goethe-Universität Frankfurt am Main (Germany)
5. Univ. of Chicago, Lemont, IL (United States)
6. Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany)
7. European Synchrotron Radiation Facility (ESRF), Grenoble (France)
8. Argonne National Laboratory (ANL), Argonne, IL (United States)

Synchrotron X-ray diffraction (XRD) and Raman spectroscopy in laser heated diamond anvil cells and first principles molecular dynamics (FPMD) calculations have been used to investigate the reactivity of calcite and molecular hydrogen (H₂) at high pressures up to 120 GPa. We find that hydrogen reacts with calcite starting below 0.5 GPa at room temperature forming chemical bonds with carbon and oxygen. This results in the unit cell volume expansion; the hydrogenation level is much higher for powdered samples. Single-crystal XRD measurements at 8–24 GPa reveal the presence of previously reported III, IIIb, and VI calcite phases; some crystallites show up to 4% expansion, which is consistent with the incorporation of ≤ 1 hydrogen atom per formula unit. At 40–102 GPa XRD patterns of hydrogenated calcite demonstrate broadened features consistent with the calcite VI structure with incorporated hydrogen atoms. Above 80 GPa, the C–O stretching mode of calcite splits suggesting a change in the coordination of C–O bonds. Laser heating at 110 GPa results in the formation of C–C bonds manifested in the crystallization of diamond recorded by in situ XRD at 300 K and 110 GPa and by Raman spectroscopy on recovered samples commenced with C¹³ calcite. We explored several theoretical models, which show that incorporation of atomic hydrogen results in local distortions of CO₃ groups, formation of corner-shared C–O polyhedra, and chemical bonding of H to C and O, which leads to the lattice expansion and vibrational features consistent with the experiments. In conclusion, the experimental and theoretical results support recent reports on tetrahedral C coordination in high-pressure carbonate glasses and suggest a possible source of the origin of ultradeep diamonds.

• Research Organization: Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
• Sponsoring Organization: Deutsche Forschungsgemeinschaft (DFG); National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 2569851
• Journal Information: Physics of the Earth and Planetary Interiors, Journal Name: Physics of the Earth and Planetary Interiors Vol. 354; ISSN 0031-9201
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Calcite
Carbonates
Chemical bonds
High pressure
Hydrogenation
Structure