Thermal expansion of SiC at high pressure-temperature and implications for thermal convection in the deep interiors of carbide exoplanets
[4];
- Arizona State Univ., Tempe, AZ (United States)
- Carnegie Inst. of Washington, Argonne, IL (United States). Geophysical Lab., High Pressure Collaborative Access Team (HPCAT)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
- Univ. of Chicago, IL (United States). Center for Advanced Radiation Sources (CARS)
Recent astrophysical observations have shown that some stars have sufficiently high carbon-to-oxygen ratios and may host planets composed mainly of carbides instead of silicates and oxides. From the low thermal expansion of SiC at 1 bar, it can be inferred that the buoyancy force of thermal anomalies is much lower in the carbide planets than in the silicate planets. However, numerous studies have shown that high pressure in planetary interiors can fundamentally change the physical properties of materials. In this work we have measured the pressure-volume-temperature relations of two SiC polymorphs (3C and 6H) at pressures and temperatures up to 80 GPa and 1900 K and 65 GPa and 1920 K, respectively, in the laser-heated diamond anvil cell combined with synchrotron X-ray diffraction. We found no evidence of dissociations of these phases up to our maximum pressure condition, supporting the stability of SiC to 1900 km depth in Earth-size Si-rich carbide planets. Following the Mie-Grüneisen approach, we fit our data to the Birch-Murnaghan or the Vinet equations of state combined with the Debye approach. We found that the pressure-induced change in the thermal expansion parameter of SiC is much smaller than that of Mg silicate perovskite (bridgmanite). Our new measurements suggest that the thermal buoyancy force may be stronger in the deep interiors of Si-rich carbide exoplanets than in the “Earth-like” silicate planets.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- National Science Foundation (NSF); USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division
- Grant/Contract Number:
- EAR1321976; EAR-1128799; FG02-94ER14466; NA0001974; FG02-99ER45775; AC02-06CH11357; AC02-05CH11231; NSFEAR-11-57758
- OSTI ID:
- 1344574
- Alternate ID(s):
- OSTI ID: 1402398
- Journal Information:
- Journal of Geophysical Research. Planets, Vol. 122, Issue 1; ISSN 2169-9097
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- ENGLISH
Web of Science
SiO 2 ‐SiC Mixtures at High Pressures and Temperatures: Implications for Planetary Bodies Containing SiC
|
journal | August 2019 |
Capturing the oxidation of silicon carbide in rocky exoplanetary interiors
|
journal | October 2018 |
Pressure dependence of the silicon carbide synthesis temperature
|
journal | April 2019 |
| Capturing the oxidation of silicon carbide in rocky exoplanetary interiors | text | January 2018 |
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