TY - JOUR
T1 - Effects of Hydrogen on the Phase Relations in Fe-FeS at Pressures of Mars-Sized Bodies
AU - Piet, H.
AU - Leinenweber, K.
AU - Greenberg, E.
AU - Prakapenka, V. B.
AU - Shim, S. H.
N1 - Funding Information:
We thank the editor and two anonymous reviewers for helpful comments to improve this paper. This work has been supported by grants NSF‐AST2005567 and NASA‐80NSSC18K0353. H. Piet and S.‐H. Shim were supported partially by the Keck Foundation. The results reported herein benefit from collaborations and information exchange within NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. Synchrotron experiments were conducted at GeoSoilEnviroCARS (University of Chicago, Sector 13), Advanced Photon Source (APS). GeoSoilEnviroCARS is supported by the NSF‐Earth Science (EAR‐1634415) and DOE‐GeoScience (DE‐FG02‐94ER14466). APS is supported by DOE‐BES under contract DE‐AC02‐06CH11357. We acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI‐ECCS‐1542160. We would also like to acknowledge Axel Wittmann from the Eyring Materials Center at Arizona State University supported in part by NNCI‐ECCS‐1542160 for his assistance with EPMA measurements.
Funding Information:
We thank the editor and two anonymous reviewers for helpful comments to improve this paper. This work has been supported by grants NSF-AST2005567 and NASA-80NSSC18K0353. H. Piet and S.-H. Shim were supported partially by the Keck Foundation. The results reported herein benefit from collaborations and information exchange within NASA's Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA's Science Mission Directorate. Synchrotron experiments were conducted at GeoSoilEnviroCARS (University of Chicago, Sector 13), Advanced Photon Source (APS). GeoSoilEnviroCARS is supported by the NSF-Earth Science (EAR-1634415) and DOE-GeoScience (DE-FG02-94ER14466). APS is supported by DOE-BES under contract DE-AC02-06CH11357. We acknowledge the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160. We would also like to acknowledge Axel Wittmann from the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160 for his assistance with EPMA measurements.
Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.
PY - 2021/11
Y1 - 2021/11
N2 - The large radius, and therefore low density, of the Martian core found in the InSight mission data analysis highlights the importance of considering other light elements besides sulfur (S), which has been considered as the main light element for Mars for decades. Hydrogen (H) is abundant in the solar system and becomes siderophile at high pressures. Although Fe-S and Fe-H systems have been studied individually, the Fe-S-H ternary system has only been investigated up to 16 GPa and 1723 K. We have investigated the Fe-S-H system at pressures and temperatures (P-T) relevant to the cores of Mars-sized planets (up to 45 GPa and well above the melting temperature of FeS) in the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. We found that sufficient hydrogen leads to the disappearance of Fe3S at high P-T. Instead, separate Fe-H and Fe-S phases appear at 23–35 GPa. At pressures above 35 GPa, we found a new phase appearing while Fe-S phases disappear and Fe-H phases remain. Our analysis indicates that the new phase likely contains both S and H in the crystal structure (tentatively FeSxHy where x ≈ 1 and y ≈ 1). The observed pressure-dependent changes in the phase relation may be important for understanding the structure and dynamics of the Martian core and the cores of Mars-sized exoplanets.
AB - The large radius, and therefore low density, of the Martian core found in the InSight mission data analysis highlights the importance of considering other light elements besides sulfur (S), which has been considered as the main light element for Mars for decades. Hydrogen (H) is abundant in the solar system and becomes siderophile at high pressures. Although Fe-S and Fe-H systems have been studied individually, the Fe-S-H ternary system has only been investigated up to 16 GPa and 1723 K. We have investigated the Fe-S-H system at pressures and temperatures (P-T) relevant to the cores of Mars-sized planets (up to 45 GPa and well above the melting temperature of FeS) in the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. We found that sufficient hydrogen leads to the disappearance of Fe3S at high P-T. Instead, separate Fe-H and Fe-S phases appear at 23–35 GPa. At pressures above 35 GPa, we found a new phase appearing while Fe-S phases disappear and Fe-H phases remain. Our analysis indicates that the new phase likely contains both S and H in the crystal structure (tentatively FeSxHy where x ≈ 1 and y ≈ 1). The observed pressure-dependent changes in the phase relation may be important for understanding the structure and dynamics of the Martian core and the cores of Mars-sized exoplanets.
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U2 - 10.1029/2021JE006942
DO - 10.1029/2021JE006942
M3 - Article
AN - SCOPUS:85119870950
SN - 2169-9097
VL - 126
JO - Journal of Geophysical Research: Planets
JF - Journal of Geophysical Research: Planets
IS - 11
M1 - e2021JE006942
ER -