TY - JOUR
T1 - Sound velocity measurements in liquid Fe-S at high pressure
T2 - Implications for Earth's and lunar cores
AU - Nishida, Keisuke
AU - Kono, Yoshio
AU - Terasaki, Hidenori
AU - Takahashi, Suguru
AU - Ishii, Miho
AU - Shimoyama, Yuta
AU - Higo, Yuji
AU - Funakoshi, Ken Ichi
AU - Irifune, Tetsuo
AU - Ohtani, Eiji
N1 - Funding Information:
The authors acknowledge T. Sakaiya for technical assistance and Y. Ito for EPMA (electron microprobe) analysis. We also thank D. Zhao, A. Suzuki, Y. Shibazaki, and S. Ozawa for useful suggestions and discussions. This work was supported by a Grant-in-Aid for Specially promoted Research (no. 22000002 ) to EO. KN was supported by a Grant-in-Aid for JSPS Fellows (no. 09J04192 ). This work was also partially supported by the Global Center-of-Excellence Program, “Global Education and Research Center for Earth and Planetary Dynamics.” The experiments were performed with the approval of SPring-8 (Proposal numbers: 2009B1075 and 2010A1793 to YK, and 2010B1681 and 2011A1594 to KN).
Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013/1/5
Y1 - 2013/1/5
N2 - The P-wave velocity (VP) of liquid Fe57S43 was measured up to 5.4GPa using an ultrasonic method combined with the synchrotron X-ray technique. The VP of liquid Fe57S43 showed little change with temperature, but increased almost linearly from 3105±11m/s to 3845±9m/s with increasing pressure from 2.4 to 5.4GPa. This can be approximated by VP [m/s]=2664+205.4×P, where P is the pressure in GPa. The VP of liquid Fe57S43 at 2.4-5.4GPa was significantly lower than that of pure liquid Fe. However, the pressure dependence of VP of the liquid Fe57S43 was markedly higher than that of pure liquid Fe. The marked difference in the pressure dependences of VP between pure liquid Fe and liquid Fe57S43 may cause VP crossover at around 7GPa. As a result, the VP of liquid Fe57S43 would become higher than that of pure liquid Fe at pressures higher than 7GPa. Thus, S decreases VP at low pressures such as those of the lunar outer core, but would increase it at the high pressures of the Earth's outer core. Assuming the lunar core consists of a liquid Fe-FeS outer core and a solid Fe inner core, the expected VP in the lunar outer core ranges from 3756 to 4230m/s.
AB - The P-wave velocity (VP) of liquid Fe57S43 was measured up to 5.4GPa using an ultrasonic method combined with the synchrotron X-ray technique. The VP of liquid Fe57S43 showed little change with temperature, but increased almost linearly from 3105±11m/s to 3845±9m/s with increasing pressure from 2.4 to 5.4GPa. This can be approximated by VP [m/s]=2664+205.4×P, where P is the pressure in GPa. The VP of liquid Fe57S43 at 2.4-5.4GPa was significantly lower than that of pure liquid Fe. However, the pressure dependence of VP of the liquid Fe57S43 was markedly higher than that of pure liquid Fe. The marked difference in the pressure dependences of VP between pure liquid Fe and liquid Fe57S43 may cause VP crossover at around 7GPa. As a result, the VP of liquid Fe57S43 would become higher than that of pure liquid Fe at pressures higher than 7GPa. Thus, S decreases VP at low pressures such as those of the lunar outer core, but would increase it at the high pressures of the Earth's outer core. Assuming the lunar core consists of a liquid Fe-FeS outer core and a solid Fe inner core, the expected VP in the lunar outer core ranges from 3756 to 4230m/s.
KW - Core
KW - Fe-S
KW - High pressure
KW - Liquid
KW - Sound velocity
KW - Ultrasonic
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U2 - 10.1016/j.epsl.2012.11.042
DO - 10.1016/j.epsl.2012.11.042
M3 - Article
AN - SCOPUS:84872225065
SN - 0012-821X
VL - 362
SP - 182
EP - 186
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -