Japan Geoscience Union Meeting 2015

Presentation information

International Session (Oral)

Symbol S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Techtonophysics

[S-IT06] Early Earth - from accumulation to formation -

Mon. May 25, 2015 11:00 AM - 11:45 AM 303 (3F)

Convener:*Tatsuya Sakamaki(Department of Earth Science, Tohoku University), Akio Suzuki(Department of Earth and Planetary Materials Science, Faculty of Science, Tohoku University), Seiji Kamada(Graduate school of Science, Tohoku University), Bjorn Mysen(Geophysical Laboratory, Carnegie Inst. Washington), Chair:Tatsuya Sakamaki(Department of Earth Science, Tohoku University)

11:36 AM - 11:39 AM

[SIT06-P04] The effect of Ni and C on sound velocity of liquid Fe at high pressure

3-min talk in an oral session

Soma Kuwabara1, *Hidenori TERASAKI1, Yuta Shimoyama1, Keisuke Nishida2, Yuji Higo3, Yusaku Takubo1, Yuki Shibazaki4, Masaki Tahara4, Mako Igarashi4, Tatsuya Sakamaki4, Yoshinori Tange3, Tadashi Kondo1 (1.Department of Earth and Space Science, Osaka University, 2.Department of Earth and Planetary Science, The University of Tokyo, 3.Japan Synchrotron Radiation Research Institute, 4.Department of Earth and Planetary Materials Science, Tohoku University)

Keywords:Sound velocity, Fe alloy, Core, High pressure

Nickel is a highly plausible element in the terrestrial core together with iron. However, the effect of Ni on elastic properties of liquid Fe at high pressure has not been reported. It is important to study the effect of Ni together with light elements on the sound velocity of liquid Fe to give a constraint on the liquid core composition of terrestrial planets by comparing with the observed seismic data. In this study, we focused on the effect of Ni and C on the P-wave velocity and elastic properties of liquid Fe up to 6.5 GPa.
High pressure experiments were carried out using 1500 ton Kawai-type multi-anvil press at BL04B1 beamline, SPring-8 synchrotron facility. P-wave velocity (VP) was measured using pulse-echo overlap method. Used sample compositions were Fe-10wt%Ni and Fe-10wt%-4wt%C. The sample pellet was sandwiched by single crystal sapphire buffer rods for the VP measurement. The experimental pressures and temperatures were determined based on lattice volumes of MgO and BN, which were used as a pressure marker, combined with their equations of state. The measurements were performed up to 6.5 GPa and 2100 K.
Obtained VP of liquid Fe-Ni is located slightly lower and aligned almost parallel to the VP curve of liquid Fe as a function of pressure. This suggests that alloying 10 wt% of Ni into liquid Fe slightly decrease the VP but little influence on the bulk modulus and its pressure dependence. Alloying C slightly increases the VP of liquid Fe and it is also found that the effect of temperature on the VP is not negligible. In the presentation, we will compare these results with the reported results of other light element such as S in the sound velocity-density relation (Birch plot) and discuss a clue to constrain the core composition of small terrestrial planets.