Hydrocarbons under Pressure: Phase Diagrams and Surprising New Compounds in the C–H System
| Autor: | S. V. Lepeshkin, Artem R. Oganov, Anastasia S. Naumova |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Condensed Matter - Materials Science
Chemistry Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials General Energy Computational chemistry Physical and Theoretical Chemistry 0210 nano-technology Phase diagram |
| Zdroj: | The Journal of Physical Chemistry C. 123:20497-20501 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/acs.jpcc.9b01353 |
| Popis: | Understanding the high-pressure behavior of C-H system is of great importance due to its key role in organic, bio-, petroleum and planetary chemistry. We have performed a systematic investigation of the pressure-composition phase diagram of the C-H system at pressures up to 400 GPa using evolutionary structure prediction coupled with ab initio calculations and discovered that only saturated hydrocarbons are thermodynamically stable. Several stable methane-hydrogen co crystals are predicted: 2CH4 * H2, earlier obtained experimentally, is predicted to have I4/m space group and 2-90 GPa stability range at 0 K, and two new thermodynamically stable compounds 2CH4 * 7H2 (P-3m1 space group) and CH4 * 9H2 (Cm space group), as potential energy storage materials. P21/c phase of methane is predicted to be stable at pressures < 8 GPa; bulk graphane (CH) was shown to be thermodynamically stable at 7-18 and 18-50 GPa and 0 K in the P-3m and Cmca phases, respectively; polyethylene is shown to have a narrow field of stability. We report the p-T-x phase diagram of the C-H system and p-T phase diagram of CH4. |
| Databáze: | OpenAIRE |
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