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Koller TJ, Jin S, Krol V, Ambach SJ, Ranieri U, Khandarkhaeva S, Spender J, McWilliams S, Trybel F, Giordano N, Poreba T, Mezouar M, Kuang X, Lu C, Dubrovinsky L, Dubrovinskaia N, Hermann A, Schnick W, Laniel D. Simple Molecules under High-Pressure and High-Temperature Conditions: Synthesis and Characterization of α- and β-C(NH) 2 with Fully sp 3 -Hybridized Carbon. Angew Chem Int Ed Engl 2024; 63:e202318214. [PMID: 38100520 DOI: 10.1002/anie.202318214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 12/17/2023]
Abstract
The elements hydrogen, carbon, and nitrogen are among the most abundant in the solar system. Still, little is known about the ternary compounds these elements can form under the high-pressure and high-temperature conditions found in the outer planets' interiors. These materials are also of significant research interest since they are predicted to feature many desirable properties such as high thermal conductivity and hardness due to strong covalent bonding networks. In this study, the high-pressure high-temperature reaction behavior of malononitrile H2 C(CN)2 , dicyandiamide (H2 N)2 C=NCN, and melamine (C3 N3 )(NH2 )3 was investigated in laser-heated diamond anvil cells. Two previously unknown compounds, namely α-C(NH)2 and β-C(NH)2 , have been synthesized and found to have fully sp3 -hybridized carbon atoms. α-C(NH)2 crystallizes in a distorted β-cristobalite structure, while β-C(NH)2 is built from previously unknown imide-bridged 2,4,6,8,9,10-hexaazaadamantane units, which form two independent interpenetrating diamond-like networks. Their stability domains and compressibility were studied, for which supporting density functional theory calculations were performed.
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Affiliation(s)
- Thaddäus J Koller
- Department of Chemistry, University of Munich (LMU), Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Siyu Jin
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China
| | - Viktoria Krol
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Sebastian J Ambach
- Department of Chemistry, University of Munich (LMU), Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Umbertoluca Ranieri
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Saiana Khandarkhaeva
- Bavarian Research Institute of Experimental Geochemistry and Geophysics (BGI), University of Bayreuth, 95440, Bayreuth, Germany
| | - James Spender
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Stewart McWilliams
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Florian Trybel
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 58183, Linköping, Sweden
| | - Nico Giordano
- P02.2 Extreme Conditions Beamline, Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607, Hamburg, Germany
| | - Tomasz Poreba
- ID27 High Pressure Beamline, European Synchrotron Radiation Facility (ESRF), 71 avenue des Martyrs, 38000, Grenoble, France
| | - Mohamed Mezouar
- ID27 High Pressure Beamline, European Synchrotron Radiation Facility (ESRF), 71 avenue des Martyrs, 38000, Grenoble, France
| | - Xiaoyu Kuang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, China
| | - Cheng Lu
- School of Mathematics and Physics, China University of Geosciences (Wuhan), Wuhan, 430074, China
| | - Leonid Dubrovinsky
- Bavarian Research Institute of Experimental Geochemistry and Geophysics (BGI), University of Bayreuth, 95440, Bayreuth, Germany
| | - Natalia Dubrovinskaia
- Bavarian Research Institute of Experimental Geochemistry and Geophysics (BGI), University of Bayreuth, 95440, Bayreuth, Germany
| | - Andreas Hermann
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
| | - Wolfgang Schnick
- Department of Chemistry, University of Munich (LMU), Butenandtstrasse 5-13, 81377, Munich, Germany
| | - Dominique Laniel
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh, EH9 3FD, UK
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de Villa K, González-Cataldo F, Militzer B. Double superionicity in icy compounds at planetary interior conditions. Nat Commun 2023; 14:7580. [PMID: 37990010 PMCID: PMC10663582 DOI: 10.1038/s41467-023-42958-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 10/27/2023] [Indexed: 11/23/2023] Open
Abstract
The elements hydrogen, carbon, nitrogen and oxygen are assumed to comprise the bulk of the interiors of the ice giant planets Uranus, Neptune, and sub-Neptune exoplanets. The details of their interior structures have remained largely unknown because it is not understood how the compounds H2O, NH3 and CH4 behave and react once they have been accreted and exposed to high pressures and temperatures. Here we study thirteen H-C-N-O compounds with ab initio computer simulations and demonstrate that they assume a superionic state at elevated temperatures, in which the hydrogen ions diffuse through a stable sublattice that is provided by the larger nuclei. At yet higher temperatures, four of the thirteen compounds undergo a second transition to a novel doubly superionic state, in which the smallest of the heavy nuclei diffuse simultaneously with hydrogen ions through the remaining sublattice. Since this transition and the melting transition at yet higher temperatures are both of first order, this may introduce additional layers in the mantle of ice giant planets and alter their convective patterns.
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Affiliation(s)
- Kyla de Villa
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA.
| | - Felipe González-Cataldo
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA
| | - Burkhard Militzer
- Department of Earth and Planetary Science, University of California, Berkeley, CA, 94720, USA
- Department of Astronomy, University of California, Berkeley, CA, 94720, USA
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Conway LJ, Pickard CJ, Hermann A. Rules of formation of H-C-N-O compounds at high pressure and the fates of planetary ices. Proc Natl Acad Sci U S A 2021; 118:e2026360118. [PMID: 33931549 PMCID: PMC8126778 DOI: 10.1073/pnas.2026360118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The solar system's outer planets, and many of their moons, are dominated by matter from the H-C-N-O chemical space, based on solar system abundances of hydrogen and the planetary ices [Formula: see text]O, [Formula: see text], and [Formula: see text] In the planetary interiors, these ices will experience extreme pressure conditions, around 5 Mbar at the Neptune mantle-core boundary, and it is expected that they undergo phase transitions, decompose, and form entirely new compounds. While temperature will dictate the formation of compounds, ground-state density functional theory allows us to probe the chemical effects resulting from pressure alone. These structural developments in turn determine the planets' interior structures, thermal evolution, and magnetic field generation, among others. Despite its importance, the H-C-N-O system has not been surveyed systematically to explore which compounds emerge at high-pressure conditions, and what governs their stability. Here, we report on and analyze an unbiased crystal structure search among H-C-N-O compounds between 1 and 5 Mbar. We demonstrate that simple chemical rules drive stability in this composition space, which explains why the simplest possible quaternary mixture HCNO-isoelectronic to diamond-emerges as a stable compound and discuss dominant decomposition products of planetary ice mixtures.
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Affiliation(s)
- Lewis J Conway
- Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
- School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
| | - Chris J Pickard
- Department of Materials Science & Metallurgy, University of Cambridge, Cambridge CB3 0FS, United Kingdom
- Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Andreas Hermann
- Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom;
- School of Physics and Astronomy, The University of Edinburgh, Edinburgh EH9 3FD, United Kingdom
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