TY - JOUR
T1 - Effect of hydrogen on the melting temperature of FeS at high pressure
T2 - Implications for the core of Ganymede
AU - Shibazaki, Yuki
AU - Ohtani, Eiji
AU - Terasaki, Hidenori
AU - Tateyama, Ryuji
AU - Sakamaki, Tatsuya
AU - Tsuchiya, Taku
AU - Funakoshi, Ken ichi
N1 - Funding Information:
We thank Y. Fukai and S. Urakawa for useful suggestions and discussions. We also thank Y. Higo for helping with the in situ X-ray diffraction experiments. We appreciate the anonymous reviewers for their constructive comments. This work was supported by the grants-in-aid of Scientific Research from the Ministry of Education, Culture, Science, Sport, and Technology of the Japanese Government (nos. 18104009 and 22000002 ) to EO. YS was supported by a Research Fellow of the Japan Society for the Promotion of Science . This work was conducted as a part of the Global COE Program at Tohoku University, “Global Education and Research Center for Earth and Planetary Dynamics”. The synchrotron radiation experiments were performed at the BL04B1 beamline at the SPring-8 facility with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (proposal nos. 2008B1439 and 2009A1206).
PY - 2011/1/3
Y1 - 2011/1/3
N2 - We have carried out in situ X-ray diffraction experiments on the FeS-H system up to 16.5GPa and 1723K using a Kawai-type multianvil high-pressure apparatus employing synchrotron X-ray radiation. Hydrogen was supplied to FeS from the thermal decomposition of LiAlH4, and FeSHx was formed at high pressures and temperatures. The melting temperature and phase relationships of FeSHx were determined based on in situ powder X-ray diffraction data. The melting temperature of FeSHx was reduced by 150-250K comparing with that of pure FeS. The hydrogen concentration in FeSHx was determined to be x=0.2-0.4 just before melting occurred between 3.0 and 16.5GPa. It is considered that sulfur is the major light element in the core of Ganymede, one of the Galilean satellites of Jupiter. Although the interior of Ganymede is differentiated today, the silicate rock and the iron alloy mixed with H2O, and the iron alloy could react with H2O (as ice or water) or the hydrous silicate before the differentiation occurred in an early period, resulting in a formation of iron hydride. Therefore, Ganymede's core may be composed of an Fe-S-H system. According to our results, hydrogen dissolved in Ganymede's core lowers the melting temperature of the core composition, and so today, the core could have solid FeSHx inner core and liquid FeHx-FeSHx outer core and the present core temperature is considered to be relatively low.
AB - We have carried out in situ X-ray diffraction experiments on the FeS-H system up to 16.5GPa and 1723K using a Kawai-type multianvil high-pressure apparatus employing synchrotron X-ray radiation. Hydrogen was supplied to FeS from the thermal decomposition of LiAlH4, and FeSHx was formed at high pressures and temperatures. The melting temperature and phase relationships of FeSHx were determined based on in situ powder X-ray diffraction data. The melting temperature of FeSHx was reduced by 150-250K comparing with that of pure FeS. The hydrogen concentration in FeSHx was determined to be x=0.2-0.4 just before melting occurred between 3.0 and 16.5GPa. It is considered that sulfur is the major light element in the core of Ganymede, one of the Galilean satellites of Jupiter. Although the interior of Ganymede is differentiated today, the silicate rock and the iron alloy mixed with H2O, and the iron alloy could react with H2O (as ice or water) or the hydrous silicate before the differentiation occurred in an early period, resulting in a formation of iron hydride. Therefore, Ganymede's core may be composed of an Fe-S-H system. According to our results, hydrogen dissolved in Ganymede's core lowers the melting temperature of the core composition, and so today, the core could have solid FeSHx inner core and liquid FeHx-FeSHx outer core and the present core temperature is considered to be relatively low.
KW - Core
KW - Ganymede
KW - Hydrogen
KW - Iron sulfide
KW - Melting temperature
KW - Metal hydride
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U2 - 10.1016/j.epsl.2010.10.033
DO - 10.1016/j.epsl.2010.10.033
M3 - Article
AN - SCOPUS:78650277704
VL - 301
SP - 153
EP - 158
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
IS - 1-2
ER -