Updated on 2024/03/13

写真a

 
TERASAKI Hidenori
 
Organization
Faculty of Environmental, Life, Natural Science and Technology Professor
Position
Professor
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Degree

  • 理学博士 ( 筑波大学 )

Research Interests

  • Iron alloy

  • Core

  • Physical properties of liquids

  • High Pressure Experiments

  • Planetary interior structure

  • Differentiation of planetary interiors

Research Areas

  • Natural Science / Solid earth sciences

Education

  • University of Tsukuba   大学院地球科学研究科  

    1997.4 - 2002.3

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  • University of Tsukuba   第一学群自然学類  

    1993.4 - 1997.3

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Research History

  • Okayama University   The Graduate School of Natural Science and Technology   Professor

    2020.4

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    Country:Japan

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  • Osaka University   Graduate school of Science, Department of Earth and Space Science   Associate Professor

    2011.4 - 2020.3

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  • Tohoku University   Graduate school of Science, Department of Earth and Planetary Materials Science   Assistant Professor

    2004.4 - 2011.3

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  • University of Bayreuth   Bayerisches Geoinstitut   Postdoctoral fellow

    2002.4 - 2004.3

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Professional Memberships

  • THE JAPAN SOCIETY OF HIGH PRESSURE SCIENCE AND TECHNOLOGY

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  • American Geophysical Union

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  • THE IRON AND STEEL INSTITUTE OF JAPAN

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  • THE JAPANESE SOCIETY FOR PLANETARY SCIENCES

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  • Japan Association of Mineralogical Sciences

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Committee Memberships

  • 日本高圧力学会   会計幹事・評議員  

    2023.9   

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  • 日本高圧力学会   渉外幹事・評議員  

    2014.9 - 2016.8   

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    Committee type:Academic society

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  • 日本高圧力学会   高圧討論会実行委員  

    2011.11 - 2012.11   

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  • 日本鉱物科学会   Elements委員  

    2011.10   

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    Committee type:Academic society

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  • 日本鉱物科学会   行事委員  

    2011.10   

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  • 日本高圧力学会   高圧討論会実行委員  

    2009.11 - 2010.11   

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Papers

  • Wetting property of Fe–S melt in solid core: Implication for the core crystallization process in planetesimals Reviewed International journal

    Shiori Matsubara, Hidenori Terasaki, Takashi Yoshino, Satoru Urakawa, Daisuke Yumitori

    Meteoritics and Planetary Science   2024.3

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Wiley  

    DOI: 10.1111/maps.14149

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  • Deuterium Content and Site Occupancy in Iron Sulfide at High Pressure and Temperature Determined Using In Situ Neutron Diffraction Measurements Reviewed International coauthorship International journal

    Sumith Abeykoon, Christopher Howard, Serena Dominijanni, Lisa Eberhard, Alexander Kurnosov, Daniel J. Frost, Tiziana Boffa Ballaran, Hidenori Terasaki, Tatsuya Sakamaki, Akio Suzuki, Eiji Ohtani, Asami Sano‐Furukawa, Jun Abe

    Journal of Geophysical Research: Solid Earth   128 ( 9 )   2023.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:American Geophysical Union (AGU)  

    Abstract

    We have performed in situ time‐of‐flight neutron diffraction experiments to examine the uptake of deuterium in iron monosulfide at pressures up to 11.4 GPa and temperatures to 1300 K. A D2 fluid was formed in the experiments through the decomposition of ND3BD3, resulting in an oxygen fugacity of approximately 1.2 log units below the iron‐wüstite buffer. Deuterium positions and site occupancies were determined in FeS V, using Rietveld refinements of the powder neutron diffraction patterns. Our structural model indicates that two normally unoccupied sites in the P63/mmc FeS V structure, at Wyckoff positions 6h and 4f, are partially occupied by D atoms, with the latter being more dominant. The deuterium content Dx in FeSDX increases with both pressure and temperature over the experimental conditions explored, from 0.126 (14) at 2.3 GPa and 787 K to 1.20 (16) at 9.7 GPa and 1300 K. The unit‐cell volume expansion per deuterium atom is 1.53 ± 0.16 Å3 at 6.9 GPa and 960 K, which is smaller than that determined for metallic iron phases at similar conditions. The variation in unit‐cell volume indicates that most deuterium is lost from FeS V upon temperature quenching at high‐pressures. By fitting the obtained FeS V deuterium site occupancies to a thermodynamic model, estimates for the hydrogen contents of iron monosulfide at conditions and oxygen fugacities consistent with the base of the cratonic lithosphere can be made. This results in values in the range of 1,700–2,700 ppm, which contribute to approximately 2–3 ppm hydrogen in the bulk mantle.

    DOI: 10.1029/2023jb026710

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  • Density Measurements of Fe-Ni-S Liquids at High Pressure Reviewed

    Satoru Urakawa, Hidenori Terasaki, Syun-pachi Kishimoto, Naonori Inoue, Yuta Shimoyama, Yusaku Takubo, Akihiko Machida

    SPring-8/SACLA Research Report   11   218 - 220   2023.8

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    Language:English  

    DOI: 10.18957/rr.11.4.218

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  • Sound velocity and elastic properties of Fe–Ni–S–Si liquid: the effects of pressure and multiple light elements Reviewed International journal

    Iori Yamada, Hidenori Terasaki, Satoru Urakawa, Tadashi Kondo, Akihiko Machida, Yoshinori Tange, Yuji Higo

    Physics and Chemistry of Minerals   50 ( 3 )   2023.7

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    Abstract

    Fe–Ni–S–Si alloy is considered to be one of the plausible candidates of Mercury core material. Elastic properties of Fe–Ni–S–Si liquid are important to reveal the density profile of the Mercury core. In this study, we measured the P-wave velocity (VP) of Fe–Ni–S–Si (Fe73Ni10S10Si7, Fe72Ni10S5Si13, and Fe67Ni10S10Si13) liquids up to 17 GPa and 2000 K to study the effects of pressure, temperature, and multiple light elements (S and Si) on the VP and elastic properties.

    The VP of Fe–Ni–S–Si liquids are less sensitive to temperature. The effect of pressure on the VP are close to that of liquid Fe and smaller than those of Fe–Ni–S and Fe–Ni–Si liquids. Obtained elastic properties are KS0 = 99.1(9.4) GPa, KS’ = 3.8(0.1) and ρ0 =6.48 g/cm3 for S-rich Fe73Ni10S10Si7 liquid and KS0 = 112.1(1.5) GPa, KS’ = 4.0(0.1) and ρ0=6.64 g/cm3 for Si-rich Fe72Ni10S5Si13 liquid. The VP of Fe–Ni–S–Si liquids locate in between those of Fe–Ni–S and Fe–Ni–Si liquids. This suggests that the effect of multiple light element (S and Si) on the VP is suppressed and cancel out the effects of single light elements (S and Si) on the VP. The effect of composition on the EOS in the Fe–Ni–S–Si system is indispensable to estimate the core composition combined with the geodesy data of upcoming Mercury mission.

    DOI: 10.1007/s00269-023-01243-8

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    Other Link: https://link.springer.com/article/10.1007/s00269-023-01243-8/fulltext.html

  • Density and elastic properties of liquid gallium up to 10 GPa using X-ray absorption method combined with externally heated diamond anvil cell Reviewed International journal

    Ryo Tsuruoka, Hidenori Terasaki, Seiji Kamada, Fumiya Maeda, Tadashi Kondo, Naohisa Hirao, Saori I. Kawaguchi, Iori Yamada, Satoru Urakawa, Akihiko Machida

    High Pressure Research   41 ( 4 )   379 - 391   2021.10

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Informa UK Limited  

    The density of liquid metals at high pressure and high-temperature provides fundamental and important information for understanding their compression behavior and elastic properties. In this study, the densities of liquid gallium (Ga) were measured up to 10 GPa and 533 K using the X-ray absorption method combined with an externally heated diamond anvil cell. The elastic properties (the isothermal bulk modulus (K-T0), and its pressure derivative (K-T0')) of liquid Ga were obtained by fitting the density data with three equations of state (EOSs) (Murnaghan, third order Birch-Murnaghan, and Vinet). The K-T0 values of liquid Ga were determined to be 45.7 +/- 1.0-51.7 +/- 1.0 GPa at 500 K assuming K-T0' values of 4-6. The obtained K-T0 or K-T0 ' showed almost the same values regardless of the EOS used. Compared with previous results, the compression curve of liquid Ga obtained in this study had a slightly stiffer trend at higher pressures.

    DOI: 10.1080/08957959.2021.1998478

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  • In situ observation of the Rayleigh–Taylor instability of liquid Fe and Fe–Si alloys under extreme conditions: Implications for planetary core formation Reviewed International journal

    Hidenori Terasaki, Tatsuhiro Sakaiya, Keisuke Shigemori, Kosaku Akimoto, Hiroki Kato, Yoichiro Hironaka, Tadashi Kondo

    Matter and Radiation at Extremes   6 ( 5 )   054403 - 054403   2021.9

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:AIP Publishing  

    DOI: 10.1063/5.0029448

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  • Precise determination of the effect of temperature on the density of solid and liquid iron, nickel, and tin Reviewed International journal

    Asaka Kamiya, Hidenori Terasaki, Tadashi Kondo

    American Mineralogist   106 ( 7 )   1077 - 1082   2021.7

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Mineralogical Society of America  

    <title>Abstract</title>
    Density and thermal expansion coefficient of metals are fundamental characteristics to describe the equation of state. Especially for liquid metals, the reported data for density and thermal expansion coefficient vary in the literature, even at ambient pressure. To determine the density of solid and liquid metals precisely at high temperatures and ambient pressure, we have developed a high-temperature furnace. The densities of solid Sn, Ni, and Fe were determined from the sample image with an uncertainty of 0.11–0.7% in the temperature range of 285–1803 K with increments of 1–10 K. The density of solid Sn decreased linearly with increasing temperature up to 493 K, and then the decrease became drastic until the melting temperature (Tm) was reached. By contrast, for solid Ni and Fe, the densities decreased linearly with increasing temperature up to the Tm (1728 and 1813 K) without any drastic density drop near Tm. This suggests that Ni and Fe do not exhibit the “premelting effect.”


    The density of liquid Fe was determined with an uncertainty of 0.4–0.7% in the range of 1818–1998 K with temperature increments of 5 K. The obtained thermal expansion coefficient (α) of liquid Fe was well approximated as either a constant value of α = 2.42(1) × 10–4 K–1 or a linear function of temperature (T); α = 1.37(10) × 10–3 – [6.0(6) × 10–7]T [K–1] up to at least 2000 K.

    DOI: 10.2138/am-2021-7509

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  • Thermocapillary effects in two-phase medium and applications to metal-silicate separation Reviewed International coauthorship International journal

    Yanick Ricard, Stéphane Labrosse, Hidenori Terasaki, David Bercovici

    Physics of the Earth and Planetary Interiors   311   106640 - 106640   2021.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.pepi.2020.106640

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  • Effect of sulfur on sound velocity of liquid iron under Martian core conditions Reviewed International journal

    Keisuke Nishida, Yuki Shibazaki, Hidenori Terasaki, Yuji Higo, Akio Suzuki, Nobumasa Funamori, Kei Hirose

    Nature Communications   11 ( 1 )   2020.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    DOI: 10.1038/s41467-020-15755-2

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    Other Link: http://www.nature.com/articles/s41467-020-15755-2

  • Surface structure on diamond foils generated by spatially nonuniform laser irradiation Reviewed International journal

    Hiroki Kato, Hideo Nagatomo, Mitsuo Nakai, Tatsuhiro Sakaiya, Hidenori Terasaki, Tadashi Kondo, Yoichiro Hironaka, Katsuya Shimizu, Keisuke Shigemori

    Scientific Reports   10 ( 1 )   2020.12

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    <title>Abstract</title>Here we report on the effects of material strength factors on the generation of surface structure due to nonuniform laser irradiation. The influence of material strength on the generation of perturbation on a diamond surface subjected to nonuniform laser irradiation was experimentally investigated. Our previous investigations suggested that stiffer and denser materials reduce surface perturbation due to spatially nonuniform laser irradiation, which was reproduced well by calculations with multi-dimensional hydrodynamic simulation code. In this work, we found that local fractures due to yield strength failure are generated by high degrees of irradiation non-uniformity. A characteristic crack-like surface structure was observed, which was not reproduced by the 2D simulation code calculations at all. The 2D simulations showed that the pressure at the diamond surface locally exceeds the Hugoniot elastic limit due to nonuniform irradiation, implying the potential for development of surface perturbations. We also measured the areal-density distribution of perturbations for single-crystal diamond and diamond with a thin high atomic number (high-Z) coating on its surface. The experimental results imply that the combination of a stiff material and thin high-Z coating can suppress the solid-strength effects caused by large irradiation non-uniformity. The knowledge given here is applicable to inertial confinement fusion target design, laser material processing, and universal problems involving solids and high-energy-density plasmas.

    DOI: 10.1038/s41598-020-66036-3

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    Other Link: http://www.nature.com/articles/s41598-020-66036-3

  • Physical Properties and Composition of Cores of Terrestrial Planets Reviewed

    Hidenori TERASAKI

    The Review of High Pressure Science and Technology   30 ( 2 )   111 - 117   2020

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    Authorship:Lead author   Language:Japanese   Publishing type:Research paper (scientific journal)   Publisher:The Japan Society of High Pressure Science and Technology  

    DOI: 10.4131/jshpreview.30.111

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  • Pressure and composition effects on sound velocity and density of core-forming liquids: Implication to core compositions of terrestrial planets Reviewed International coauthorship

    H. Terasaki, A. Rivoldini, Y. Shimoyama, K. Nishida, S. Urakawa, M. Maki, F. Kurokawa, Y. Takubo, Y. Shibazaki, T. Sakamaki, A. Machida, Y. Higo, K. Uesugi, A. Takeuchi, T. Watanuki, T. Kondo

    Journal of Geophysical Research: Planets   124   2272 - 2293   2019.9

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  • Interstitial hydrogen atoms in face-centered cubic iron in the Earth's core Reviewed

    Ikuta Daijo, Ohtani Eiji, Sano-Furukawa Asami, Shibazaki Yuki, Terasaki Hidenori, Yuan Liang, Hattori Takanori

    SCIENTIFIC REPORTS   9 ( 1 )   2019.5

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    Abstract

    Hydrogen is likely one of the light elements in the Earth’s core. Despite its importance, no direct observation has been made of hydrogen in an iron lattice at high pressure. We made the first direct determination of site occupancy and volume of interstitial hydrogen in a face-centered cubic (fcc) iron lattice up to 12 GPa and 1200 K using the in situ neutron diffraction method. The transition temperatures from the body-centered cubic and the double-hexagonal close-packed phases to the fcc phase were higher than reported previously. At pressures &lt;5 GPa, the hydrogen content in the fcc iron hydride lattice (x) was small at x &lt; 0.3, but increased to x &gt; 0.8 with increasing pressure. Hydrogen atoms occupy both octahedral (O) and tetrahedral (T) sites; typically 0.870(±0.047) in O-sites and 0.057(±0.035) in T-sites at 12 GPa and 1200 K. The fcc lattice expanded approximately linearly at a rate of 2.22(±0.36) Å3 per hydrogen atom, which is higher than previously estimated (1.9 Å3/H). The lattice expansion by hydrogen dissolution was negligibly dependent on pressure. The large lattice expansion by interstitial hydrogen reduced the estimated hydrogen content in the Earth’s core that accounted for the density deficit of the core. The revised analyses indicate that whole core may contain hydrogen of 80(±31) times of the ocean mass with 79(±30) and 0.8(±0.3) ocean mass for the outer and inner cores, respectively.

    DOI: 10.1038/s41598-019-43601-z

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    Other Link: https://www.nature.com/articles/s41598-019-43601-z

  • Sound velocity and density of liquid Ni68S32 under pressure using ultrasonic and X-ray absorption with tomography methods Reviewed

    Terasaki Hidenori, Nishida Keisuke, Urakawa Satoru, Takubo Yusaku, Kuwabara Soma, Shimoyama Yuta, Uesugi Kentaro, Kono Yoshio, Takeuchi Akihisa, Suzuki Yoshio, Higo Yuji, Kondo Tadashi

    COMPTES RENDUS GEOSCIENCE   351 ( 2-3 )   163 - 170   2019.2

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER  

    A new experimental setup for simultaneous P-wave velocity (V-P) and density (rho) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (K-S) and to discuss the correlation between the V-P and rho of the liquid sample. We measured V-P and rho of liquid Ni68S32 up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the V-P and rho values of liquid Ni68S32 is similar to that of liquid Fe57S43. (Both compositions correspond to near-eutectic ones.) The obtained K-S values are well fitted to the finite strain equation with a K-S0 value (K-S at ambient pressure) of 31.1 GPa and a dK(S)/dP value of 8.44. The measured V-P was found to increase linearly with increasing rho, as approximated by the relationship: V-P [m/s] = 1.29 rho [kg/m(3)] - 5726, suggesting that liquid Ni-S follows an empirical linear relationship, Birch's law. The dV(P)/d rho slope is similar between Ni68S32 and Fe57S43 liquids, while the V-P-rho plot of liquid Ni-S is markedly different from that of liquid Fe-S, which indicates that the effect of Ni on Birch's law is important for understanding the V-P-rho relation of planetary and Moon's molten cores. (C) 2018 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

    DOI: 10.1016/j.crte.2018.04.005

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  • Measurements of Rayleigh–Taylor instability growth of laser-shocked iron–silicon alloy Reviewed

    Tatsuhiro Sakaiya, Hidenori Terasaki, Kosaku Akimoto, Hiroki Kato, Taichi Ueda, Ryota Hosogi, Takashi Fujikawa, Tadashi Kondo, Yoichiro Hironaka, Keisuke Shigemori

    High Pressure Research   39 ( 1 )   150 - 159   2019.1

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    © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. The Rayleigh–Taylor (RT) instability of liquid iron alloys is important for understanding the core formation mechanism in the Earth. Here we first report the measurement of RT instability growth for a liquid iron–silicon (Fe–Si) alloy, which is one of the major candidate for the material of the Earth’s core, using a high power laser. We optimized the measurement setup and analytical technique to observe the growth of perturbation on an Fe–Si sample surface. The growth of perturbation amplitude on the Fe–Si alloy under high pressure and temperature was successfully observed using in situ X-ray radiography. The growth rate of the RT instability for the Fe–Si alloy on about 1000 GPa was estimated to be 0.3 ns −1 .

    DOI: 10.1080/08957959.2019.1575966

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  • Variations of lattice constants and thermal expansion coefficients of indium at high pressure and high temperature Reviewed

    Takubo Yusaku, Terasaki Hidenori, Kondo Tadashi, Mitai Shingo, Kamada Seiji, Kikegawa Takumi, Machida Akihiko

    HIGH PRESSURE RESEARCH   38 ( 4 )   406 - 413   2018

  • Development of density measurement for metals at high pressures and high temperatures using X-ray absorption imaging combined with externally heated diamond anvil cell Reviewed

    Yusaku Takubo, Hidenori Terasaki, Tadashi Kondo, Shingo Mitai, Seiji Kamada, Takumi Kikegawa, Akihiko Machida

    Comptes Rendus - Geoscience   351 ( 2-3 )   182 - 189   2018

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier Masson SAS  

    A technique for density measurement under high pressure and high temperature was developed using the X-ray absorption imaging method combined with an externally heated diamond anvil cell. The densities of solid and liquid In were measured in the pressure and temperature ranges of 3.2–18.6 GPa and 294–719 K. The densities obtained through the X-ray absorption imaging method were in good agreement (less than 2.0% difference) with those obtained through X-ray diffraction. Based on the measured density, the isothermal bulk modulus of solid In is determined as 48.0 ± 1.1−40.9 ± 0.8 GPa at 500 K, assuming K′ = 4 to 6. The compression curve of liquid In approaches that of solid In at higher pressures and does not cross over the solid compression curve in the measurement range. The present technique enables us to determine the densities of both solids and liquids precisely in a wide pressure and temperature range.

    DOI: 10.1016/j.crte.2018.04.002

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  • 形成期の惑星内部における鉄合金メルトとケイ酸塩の分離過程 Reviewed

    岸本俊八, 浦川啓, 寺﨑英紀, 桑原荘馬, 西田圭佑, 坂巻竜也, 竹内晃久, 上杉健太朗

    SPring-8/SACLA利用研究成果集   25   208 - 211   2018

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    Language:Japanese  

    DOI: 10.18957/rr.6.2.208

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  • Elastic wave velocity measurements of iron-silicon alloy under high pressure and temperature conditions Reviewed

    Sakamaki Tatsuya, Terasaki Hidenori, Shibazaki Yuki, Tobe Hiromu, Shimoyama Yuta, Higo Yuji, Suzuki Akio

    Abstracts for Annual Meeting of Japan Association of Mineralogical Sciences   2017 ( 0 )   103 - 103   2017

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    Language:Japanese   Publisher:Japan Association of Mineralogical Sciences  

    Elastic wave velocities and density of iron-silicon alloys were determined experimentally up to 6 GPa and 1873 K using ultrasonic and X-ray diffraction methods. We suceeded in determining the pressure- and temperature-dependences of the properties, and also found the difference between bcc and fcc structures.

    DOI: 10.14824/jakoka.2017.0_103

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  • Simultaneous sound velocity and density measurements of iron-silicon alloys under core conditions of Mercury and Mars

    Sakamaki, T, Terasaki, H, Shibazaki, Y, Suzuki, A, Tobe, H, Higo, Y, Kurokawa, F, Maki, M, Shimoyama, Y, Saito, R

    SPring-8 User Experiment Report 2016B   2016B1111   2017

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  • Thermoelastic properties of liquid Fe-C revealed by sound velocity and density measurements at high pressure Reviewed

    Yuta Shimoyama, Hidenori Terasaki, Satoru Urakawa, Yusaku Takubo, Soma Kuwabara, Shunpachi Kishimoto, Tetsu Watanuki, Akihiko Machida, Yoshinori Katayama, Tadashi Kondo

    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   121 ( 11 )   7984 - 7995   2016.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:AMER GEOPHYSICAL UNION  

    Carbon is one of the possible light elements in the cores of the terrestrial planets. The P wave velocity (V-P) and density (rho) are important factors for estimating the chemical composition and physical properties of the core. We simultaneously measured the V-P and rho of Fe-3.5 wt % C up to 3.4 GPa and 1850 K by using ultrasonic pulse-echo method and X-ray absorption methods. The V-P of liquid Fe-3.5 wt % C decreased linearly with increasing temperature at constant pressure. The addition of carbon decreased the V-P of liquid Fe by about 2% at 3 GPa and 1700 K and decreased the Fe density by about 2% at 2 GPa and 1700 K. The bulk modulus of liquid Fe-C and its pressure (P) and temperature (T) effects were precisely determined from directly measured rho and V-P data to be K-0,K-1700 K = 83.9 GPa, dK(T)/dP = 5.9(2), and dK(T)/dT = -0.063(8) GPa/K. The addition of carbon did not affect the isothermal bulk modulus (K-T) of liquid Fe, but it decreased the dK/dT of liquid Fe. In the rho-V-P relationship, V-P increases linearly with rho and can be approximated as V-P (m/s) = -6786(506) + 1537(71) x rho (g/cm(3)), suggesting that Birch's law is valid for liquid Fe-C at the present P-T conditions. Our results imply that at the conditions of the lunar core, the elastic properties of an Fe-C core are more affected by temperature than those of Fe-S core.

    DOI: 10.1002/2016JB012968

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  • Towards a consensus on the pressure and composition dependence of sound velocity in the liquid Fe-S system Reviewed

    Keisuke Nishida, Akio Suzuki, Hidenori Terasaki, Yuki Shibazaki, Yuji Higo, Souma Kuwabara, Yuta Shimoyama, Moe Sakurai, Masashi Ushioda, Eiichi Takahashi, Takumi Kikegawa, Daisuke Wakabayashi, Nobumasa Funamori

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   257   230 - 239   2016.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:ELSEVIER SCIENCE BV  

    Recent advances in techniques for high-pressure and high-temperature experiments enable us to measure the velocity of sound in liquid Fe alloys. However, reported velocities in liquid Fe S differ among research groups (e.g., by &gt;10% at 5 GPa), even when similar methods are used (i.e., the ultrasonic pulse echo overlap method combined with a large volume press). To identify the causes of the discrepancies, we reanalyzed previous data and conducted additional sound velocity measurements for liquid Fe S at 2-7 GPa, and evaluated the potential error sources. We found that the discrepancy cannot be explained by errors in the sound velocity measurements themselves, but by inaccuracies in determining the temperature, pressure, and chemical composition in each experiment. Of particular note are the significant errors introduced when determining pressures from the unit-cell volume of MgO, which is a temperature-sensitive pressure standard, using inaccurate temperatures. To solve the problem, we additionally used h-BN as a pressure standard, which is less sensitive to temperature. The pressure dependence of the sound velocity became smaller than that of the original data because of the revised pressure values. Our best estimate for the seismic velocity of the Moon's liquid outer core is 4.0 +/- 0.1 km/s, given a chemical composition Fe83S17. (C) 2016 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.pepi.2016.06.009

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  • Compressional and shear wave velocities for polycrystalline bcc-Fe up to 6.3 GPa and 800 K Reviewed

    Yuki Shibazaki, Keisuke Nishida, Yuji Higo, Mako Igarashi, Masaki Tahara, Tatsuya Sakamaki, Hidenori Terasaki, Yuta Shimoyama, Soma Kuwabara, Yusaku Takubo, Eiji Ohtani

    AMERICAN MINERALOGIST   101 ( 5-6 )   1150 - 1160   2016.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:MINERALOGICAL SOC AMER  

    The cores of the Earth and other differentiated bodies are believed to be comprised of iron and various amounts of light elements. Measuring the densities and sound velocities of iron and its alloys at high pressures and high temperatures is crucial for understanding the structure and composition of these cores. In this study, the sound velocities (v(P) and v(S)) and density measurements of body-centered cubic (bcc)-Fe were determined experimentally up to 6.3 GPa and 800 K using ultrasonic and X-ray diffraction methods. Based on the measured v(P), v(S), and density, we obtained the following parameters regarding the adiabatic bulk K-S and shear G moduli of bcc-Fe: K-50 = 163.2(15) GPa, partial derivative K-S/partial derivative P = 6.75(33), partial derivative K-S/partial derivative T = -0.038(3) GPa/K, G(0) = 81.4(6) GPa, partial derivative G/partial derivative P = 1.66(14), and partial derivative G/partial derivative T = -0.029(1) GPa/K. Moreover, we observed that the sound velocity-density relationship for bcc-Fe depended on temperature in the pressure and temperature ranges analyzed in this study and the effect of temperature on vs was stronger than that on vp at a constant density, e.g., 6.0% and 2.7% depression for v(S) and v(P), respectively, from 300 to 800 K at 8000 kg/m(3). Furthermore, the effects of temperature on both v(P) and vs at a constant density were much greater for bcc-Fe than for epsilon-FeSi (cubic B20 structure), according to previously obtained measurements, which may be attributable to differences in the degree of thermal pressure. These results suggest that the effects of temperature on the sound velocity density relationship for Fe alloys strongly depend on their crystal structures and light element contents in the range of pressure and temperature studied.

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  • Sound velocity and elastic properties of Fe-Ni and Fe-Ni-C liquids at high pressure Reviewed

    Soma Kuwabara, Hidenori Terasaki, Keisuke Nishida, Yuta Shimoyama, Yusaku Takubo, Yuji Higo, Yuki Shibazaki, Satoru Urakawa, Kentaro Uesugi, Akihisa Takeuchi, Tadashi Kondo

    PHYSICS AND CHEMISTRY OF MINERALS   43 ( 3 )   229 - 236   2016.3

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    The sound velocity (V (P)) of liquid Fe-10 wt% Ni and Fe-10 wt% Ni-4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V (P) of liquid Fe-Ni is insensitive to temperature, whereas that of liquid Fe-Ni-C tends to decrease with increasing temperature. The V (P) values of both liquid Fe-Ni and Fe-Ni-C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V (P) of liquid Fe, whereas alloying with C is likely to increase the V (P). However, a difference in V (P) between liquid Fe-Ni and Fe-Ni-C becomes to be smaller at higher temperature. By fitting the measured V (P) data with the Murnaghan equation of state, the adiabatic bulk modulus (K (S0)) and its pressure derivative (K (S) (') ) were obtained to be K (S0) = 103 GPa and K (S) (') = 5.7 for liquid Fe-Ni and K (S0) = 110 GPa and K (S) (') = 7.6 for liquid Fe-Ni-C. The calculated density of liquid Fe-Ni-C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density (rho) and sound velocity (V (P)) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that rho increased mildly and V (P) decreased, whereas the effect of C dissolution was to decrease rho but increase V (P). In contrast, alloying with S significantly reduces both rho and V (P). Therefore, the effects of light elements (C and S) and Ni on the rho and V (P) of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.

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  • Physical Properties of the Outer Core Reviewed

    Hidenori Terasaki

    Deep Earth: Physics and Chemistry of the Lower Mantle and Core   129 - 142   2015.1

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    The physical properties of liquid Fe alloys are important for understanding the characteristics of the molten outer core. The possible core composition can be constrained by matching the observed seismic data with the measured sound velocity and density of liquid Fe alloys. The transport properties of liquid Fe alloys strongly influence the convection behavior of the outer core. This chapter reviews the latest results on the elastic and transport properties of liquid Fe alloys obtained based on experimental and numerical approaches. Three variables of pressure (P), temperature (T), and specific volume (V), which are indispensable for understanding the structure and properties of Earth's interior, are linked by an equation of state (EOS). Convectional motion of the outer core is controlled by core magneto hydrodynamics. The viscosity of liquid Fe, Fe-S, and Fe-C at high pressures has been measured using the falling sphere method combined with in situ X-ray radiography.

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  • Equation of state of Fe3S at room temperature up to 2 megabars Reviewed

    Seiji Kamada, Eiji Ohtani, Hidenori Terasaki, Takeshi Sakai, Suguru Takahashi, Naohisa Hirao, Yasuo Ohishi

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   228   106 - 113   2014.3

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    The equation of state of Fe3S was investigated up to 200 GPa at room temperature using a diamond anvil cell. Fe3S adopts a tetragonal structure up to 200 GPa and no phase transition was observed. The fourth-order Birch-Murnaghan equation of state (EOS) was fitted to present compression data at room temperature. The elastic parameters, such as bulk modulus (K-0), its pressure derivative (K-0'), and K-0 ''(dK'/dP) were determined to be 122.4(50) GPa, 5.36(48), and -0.066(30) GPa(-1), respectively by fixing the zero pressure volume, V-0, to be 377 angstrom(3). Based on fourth-order Birch-Murnaghan EOS of Fe3S, the maximum amount of S in the inner core was estimated to be 11.4(14) at.% based on the density deficit of the inner core. (C) 2013 Elsevier B.V. All rights reserved.

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  • High-pressure and high-temperature phase diagram for Fe0.9Ni0.1-H alloy Reviewed

    Yuki Shibazaki, Hidenori Terasaki, Eiji Ohtani, Ryuji Tateyama, Keisuke Nishida, Ken-ichi Funakoshi, Yuji Higo

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   228   192 - 201   2014.3

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    Planetary cores are considered to consist of an iron-nickel (Fe-Ni) alloy and light elements and hydrogen is one of plausible light elements in the core. Here we have performed in situ X-ray diffraction experiments on an Fe0.9Ni0.1-H system up to 15.1 GPa and 1673 K, and investigated the effect of Ni on phase relations of FeHx under high pressure and high temperature. The experimental system in the present work was oversaturated with hydrogen. We found a face-center-cubic (fcc) phase (with hydrogen concentration up to x similar to 1) and a body-center-cubic (bcc) phase (x &lt; 0.1) as stable phases. The partial melting was observed below 6 GPa. We could not observe a double-hexagonal-close-packed (dhcp) phase because of limitations in pressure and temperature conditions. The stability field of each phase of Fe0.9Ni0.1Hx was almost same as that of FeHx. The solidus of Fe0.9Ni0.1Hx was 500-700 K lower than the melting curve of Fe and its liquidus was 400-600 K lower than that of Fe in the pressure range of this study. Both the solidus and liquidus of Fe0.9Ni0.1Hx were depressed at around 3.5 GPa, as was the solidus of FeHx. The hydrogen contents in fcc-Fe(0.9)Ni(0.1)Hx just below solidus were slightly lower than those of fcc-FeHx, which suggests that nickel is likely to prevent dissolution of hydrogen into iron. Due to the lower hydrogen solubilities in Fe0.9Ni0.1 compared to Fe, the solidus of Fe0.9Ni0.1Hx is about 100-150 K higher than that of FeHx. (C) 2013 Elsevier B.V. All rights reserved.

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  • The sound velocity measurements of Fe3S Reviewed

    Seiji Kamada, Eiji Ohtani, Hiroshi Fukui, Takeshi Sakai, Hidenori Terasaki, Suguru Takahashi, Yuki Shibazaki, Satoshi Tsutsui, Alfred Q. R. Baron, Naohisa Hirao, Yasuo Ohishi

    AMERICAN MINERALOGIST   99 ( 1 )   98 - 101   2014.1

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    We measured the sound velocity of Fe3S at room temperature up to 85 GPa employing inelastic X-ray scattering to better constrain the constitution of the inner core. The density of Fe3S was also determined by X-ray diffraction under the same conditions. The relation of the P-wave velocity (v(P)) and density (rho) of Fe3S follows Birch's law, v(P)(m/s) = 1.14(5) x rho(kg/m(3)) - 2580(410). Based on Birch's law determined here for Fe3S and that for epsilon-Fe reported previously, we found that sulfur decreases both density and compressional velocity of hcp-Fe at the core pressure and 300 K.

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  • Repulsive Nature for Hydrogen Incorporation to Fe3C up to 14 GPa Reviewed

    Hidenori Terasaki, Yuki Shibazaki, Keisuke Nishida, Ryuji Tateyama, Suguru Takahashi, Miho Ishii, Yuta Shimoyama, Eiji Ohtani, Ken-ichi Funakoshi, Yuji Higo

    ISIJ INTERNATIONAL   54 ( 11 )   2637 - 2642   2014

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    We have performed in situ X-ray diffraction measurements under high pressure and high temperature to study hydrogen solubility in Fe3C carbide. Hydrogen solubility can be estimated from a volume expansion associated with hydrogen incorporation into metal. The lattice volumes and phase relations of Fe3C H system and Fe3C were measured up to 14 GPa and 1 973 K. The lattice volumes of Fe3C measured in this study are well fitted using the 3rd order Birch Murnaghan equation of state with the reported elastic parameters of Fe3C. Obtained lattice volumes of Fe3C H are quite consistent with those of Fe3C. No difference between the melting temperatures of Fe3C H and Fe3C was observed. These results demonstrate that hydrogen incorporation into Fe3C does not occur and hydrogen is unlikely to coexist with carbon in iron-alloy up to 14 GPa.

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  • Ponded melt at the boundary between the lithosphere and asthenosphere Reviewed

    Tatsuya Sakamaki, Akio Suzuki, Eiji Ohtani, Hidenori Terasaki, Satoru Urakawa, Yoshinori Katayama, Ken-ichi Funakoshi, Yanbin Wang, John W. Hernlund, Maxim D. Ballmer

    NATURE GEOSCIENCE   6 ( 12 )   1041 - 1044   2013.12

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    The boundary between Earth's rigid lithosphere and the underlying, ductile asthenosphere is marked by a distinct seismic discontinuity(1). A decrease in seismic-wave velocity and increase in attenuation at this boundary is thought to be caused by partial melt(2). The density and viscosity of basaltic magma, linked to the atomic structure(3,4), control the process of melt separation from the surrounding mantle rocks(5-9). Here we use high-pressure and high-temperature experiments and in situ X-ray analysis to assess the properties of basaltic magmas under pressures of up to 5.5 GPa. We find that the magmas rapidly become denser with increasing pressure and show a viscosity minimum near 4 GPa. Magma mobility-the ratio of the melt-solid density contrast to the magma viscosity-exhibits a peak at pressures corresponding to depths of 120150 km, within the asthenosphere, up to an order of magnitude greater than pressures corresponding to the deeper mantle and shallower lithosphere. Melts are therefore expected to rapidly migrate out of the asthenosphere. The diminishing mobility of magma in Earth's asthenosphere as the melts ascend could lead to excessive melt accumulation at depths of 80-100 km, at the lithosphere-asthenosphere boundary. We conclude that the observed seismic discontinuity at the lithosphere-asthenosphere boundary records this accumulation of melt.

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  • Density of Fe-3.5 wt% C liquid at high pressure and temperature and the effect of carbon on the density of the molten iron Reviewed

    Yuta Shimoyama, Hidenori Terasaki, Eiji Ohtani, Satoru Urakawa, Yusaku Takubo, Keisuke Nishida, Akio Suzuki, Yoshinori Katayama

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   224   77 - 82   2013.11

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    Carbon is a plausible light element candidate in the Earth's outer core. We measured the density of liquid Fe-3.5 wt% C up to 6.8 GPa and 2200 K using an X-ray absorption method. The compression curve of liquid Fe-C was fitted using the third-order Birch-Murnaghan equation of state. The bulk modulus and its pressure derivative are K-0.1500K = 55.3 +/- 2.5 GPa and (dK(o)/dP)(T) = 5.2 +/- 1.5, and the thermal expansion coefficient is alpha = 0.86 +/- 0.04 x 10(-4) K-1. The Fe-C density abruptly increases at pressures between 4.3 and 5.5 GPa in the range of present temperatures. Compared with the results of previous density measurements of liquid Fe-C, the effect of carbon on the density of liquid Fe shows a nonideal mixing behavior. The abrupt density increase and nonideal mixing behavior are important factors in determining the light element content in the Earth's core. (C) 2013 Elsevier B.V. All rights reserved.

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  • Phase relations in the carbon-saturated C-Mg-Fe-Si-O system and C and Si solubility in liquid Fe at high pressure and temperature: Implications for planetary interiors Reviewed

    Suguru Takahashi, Eiji Ohtani, Hidenori Terasaki, Yoshinori Ito, Yuki Shibazaki, Miho Ishii, Ken ichi Funakoshi, Yuji Higo

    Physics and Chemistry of Minerals   40 ( 8 )   647 - 657   2013.9

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    The phase and melting relations of the C-saturated C-Mg-Fe-Si-O system were investigated at high pressure and temperature to understand the role of carbon in the structure of the Earth, terrestrial planets, and carbon-enriched extraterrestrial planets. The phase relations were studied using two types of experiments at 4 GPa: analyses of recovered samples and in situ X-ray diffractions. Our experiments revealed that the composition of metallic iron melts changes from a C-rich composition with up to about 5 wt.% C under oxidizing conditions (ΔIW = -1.7 to -1.2, where ΔIW is the deviation of the oxygen fugacity (fO2) from an iron-wüstite (IW) buffer) to a C-depleted composition with 21 wt.% Si under reducing conditions (ΔIW < -3.3) at 4 GPa and 1,873 K. SiC grains also coexisted with the Fe-Si melt under the most reducing conditions. The solubility of C in liquid Fe increased with increasing fO2, whereas the solubility of Si decreased with increasing fO2. The carbon-bearing phases were graphite, Fe3C, SiC, and Fe alloy melt (Fe-C or Fe-Si-C melts) under the redox conditions applied at 4 GPa, but carbonate was not observed under our experimental conditions. The phase relations observed in this study can be applicable to the Earth and other planets. In hypothetical reducing carbon planets (ΔIW < -6.2), graphite/diamond and/or SiC exist in the mantle, whereas the core would be an Fe-Si alloy containing very small amount of C even in the carbon-enriched planets. The mutually exclusive nature of C and Si may be important also for considering the light elements of the Earth's core. © 2013 Springer-Verlag Berlin Heidelberg.

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  • Sound velocity measurements in liquid Fe-S at high pressure: Implications for Earth's and lunar cores Reviewed

    Keisuke Nishida, Yoshio Kono, Hidenori Terasaki, Suguru Takahashi, Miho Ishii, Yuta Shimoyama, Yuji Higo, Ken-ichi Funakoshi, Tetsuo Irifune, Eiji Ohtani

    EARTH AND PLANETARY SCIENCE LETTERS   362   182 - 186   2013.1

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    The P-wave velocity (V-p) of liquid Fe57S43 was measured up to 5.4 GPa 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 +/- 11 m/s to 3845 +/- 9 m/s with increasing pressure from 2.4 to 5.4 GPa. This can be approximated by Vp [m/s]=2664+205.4 x P, where P is the pressure in GPa. The V-P of liquid Fe57S43 at 2.4-5.4 GPa 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 7 GPa. As a result, the Vp of liquid Fe57S43 would become higher than that of pure liquid Fe at pressures higher than 7 GPa. 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 4230 m/s. (C) 2012 Elsevier B.V. All rights reserved.

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  • Melting relationships in the Fe-Fe3S system up to the outer core conditions Reviewed

    Seiji Kamada, Eiji Ohtani, Hidenori Terasaki, Takeshi Sakai, Masaaki Miyahara, Yasuo Ohishi, Naohisa Hirao

    EARTH AND PLANETARY SCIENCE LETTERS   359   26 - 33   2012.12

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    In situ X-ray diffraction experiments in the Fe-Fe3S system were performed up to 175 GPa and 3500 K using a laser-heated diamond anvil cell to investigate melting relationships in the system. Partial melting in the Fe-Fe3S system was observed based on the disappearance of X-ray diffraction peaks of solid Fe3S and texture observation of the recovered samples. The melting relationship of the Fe-Fe3S system as a function of pressure is evaluated based on Kraut-Kennedy law. Our results of melting relationships suggest that the temperature at the inner core boundary is between 4700(160) and 4930(330) K if sulfur is the only light element in the Earth's core. Assuming the adiabatic temperature gradient in the outer core, the temperature at the core-mantle boundary is estimated to be in the range of 3600-3770 K. The present temperature profile of the core is consistent with the core-mantle boundary temperature that can explain the core heat flux to maintain the core dynamo and the seismic structure at the base of the lower mantle. (C) 2012 Elsevier B.V. All rights reserved.

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  • Density of liquids in Fe-FeO system at high pressure

    Terasaki, H, Takubo, Y, Shimoyama, Y, Suzuki, A, Nishida, K, Ohtani, E, Urakawa, S, Kondo, T, Katayama, Y

    SPring-8 User Experiment Report No.29 (2012A)   29   2012A3782   2012.11

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  • Interfacial tension of Fe-Si liquid at high pressure: Implications for liquid Fe-alloy droplet size in magma oceans Reviewed

    Hidenori Terasaki, Satoru Urakawa, David C. Rubie, Ken-ichi Funakoshi, Tatsuya Sakamaki, Yuki Shibazaki, Shin Ozawa, Eiji Ohtani

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   202   1 - 6   2012.8

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    The interfacial tension of Fe-Si liquid was measured using in situ X-ray radiography at high pressure and temperatures using the sessile drop method. The interfacial tension of Fe-Si liquid decreases (from 665 to 407 mN/m) with increasing temperature (1673-2173 K) at 1.5 GPa. The interfacial tension also decreases gradually with increasing Si content (0-25 at%), suggesting that Si behaves as a "moderately" surface-active element. Comparing the effects of different light elements on the interfacial tension of liquid iron, the most effective elements for reducing the interfacial tension lie in the order S &gt; Si &gt; P. although P has almost no effect. The droplet size of emulsified Fe-alloys in a magma ocean are estimated to be larger for Fe-Si and Fe-P liquids and smaller for Fe-S (S &gt; 10 at%) liquid compared with that for pure Fe liquid. Therefore, if droplets in a magma ocean are enriched in S, chemical equilibrium between droplets and silicate melt is established faster in the magma ocean compared to Fe, Fe-Si and Fe-P liquids. (c) 2012 Elsevier B.V. All rights reserved.

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  • In-Situ Observations of Martensitic Transformation in Blast-Resistant Steel Reviewed

    Xinghua Yu, Sudarsanam Suresh Babu, John C. Lippold, Hidenori Terasaki, Yu-ichi Komizo

    METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE   43A ( 5 )   1538 - 1546   2012.5

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    A hybrid in-situ characterization system, which couples the laser scanning confocal microscopy (LSCM) with the time-resolved X-ray diffraction (TRXRD) measurement with synchrotron radiation, was used to characterize the microstructure evolution during heat-affected zone (HAZ) thermal cycling of high-strength and blast-resistant steel. The combined technique has a time resolution of 0.3 seconds that allows for high-fidelity measurements of transformation kinetics, lattice parameters, and morphological features. The measurements showed a significant reduction in the martensite start transformation temperature with a decrease in the prior austenite grain size. In addition, the LSCM images confirmed the concurrent refinement of martensite packet size with smaller austenite grain sizes. This is consistent with dilatometric observations. The austenite grain size also influenced the rate of transformation (df (m) /dT); however, the measurements from the hybrid (surface) and dilatometric (volume) measurements were inconsistent. Challenges and future directions of adopting this technique for comprehensive tracking of microstructure evolution in steels are discussed.

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  • Stability of Fe-Ni hydride after the reaction between Fe-Ni alloy and hydrous phase (delta-AlOOH) up to 1.2 Mbar: Possibility of H contribution to the core density deficit Reviewed

    Hidenori Terasaki, Eiji Ohtani, Takeshi Sakai, Seiji Kamada, Hidetoshi Asanuma, Yuki Shibazaki, Naohisa Hirao, Nagayoshi Sata, Yasuo Ohishi, Tatsuya Sakamaki, Akio Suzuki, Ken-ichi Funakoshi

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   194   18 - 24   2012.3

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    The hydrous mineral, delta-AlOOH, is stable up to at least the core-mantle boundary, and therefore has been proposed as a water carrier to the Earth's deep mantle. If delta-AlOOH is transported down to the core-mantle boundary by a subducting slab or the mantle convection, then the reaction between the iron alloy core and delta-AlOOH is important in the deep water/hydrogen cycle in the Earth. Here we conducted an in situ X-ray diffraction study to determine the behavior of hydrogen between Fe-Ni alloys and delta-AlOOH up to near the core-mantle boundary conditions. The obtained diffraction spectra show that fcc/dhcp Fe-Ni hydride is stable over a wide pressure range of 19-121 GPa at high temperatures. Although the temperature of formation of Fe-Ni hydride tends to increase up to 1950 K with increasing pressure to 121 GPa, this reaction temperature is well below the mantle geotherm. delta-AlOOH was confirmed to coexist stably with perovskite, suggesting that delta-AlOOH can be a major hydrous phase in the lower mantle. Therefore, when delta-AlOOH contacts with the core at the core-mantle boundary, the hydrogen is likely to dissolve into the Earth's core. Based on the present results, the amount of hydrogen to explain the core density deficit is estimated to be 1.0-2.0 wt.%. (C) 2012 Elsevier B.V. All rights reserved.

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  • Compression of Fe88.1Ni9.1S2.8 alloy up to the pressure of Earth's inner core Reviewed

    Takeshi Sakai, Eiji Ohtani, Seiji Kamada, Hidenori Terasaki, Naohisa Hirao

    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   117   2012.2

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    Fe88.1Ni9.1S2.8 alloy was compressed up to 335 GPa, corresponding to the pressure at the Earth's inner core, and the hexagonal close-packed structure was found to be stable. The axial (c/a) ratio gradually decreased with increasing pressure. A linear fit as a function of pressure gave c/a = 1.605(2)-6.1(9) x 10(-5)P for P in GPa. The compression curve of Fe88.1Ni9.1S2.8 alloy was expressed by the third-order Birch-Murnaghan equation of state, giving K-0 = 167.0 +/- 15.0 GPa, K-0' = 4.46 +/- 0.14, and V-0 = 22.93 +/- 0.29 angstrom(3). Our results indicate that the hcp Fe-5 wt % Ni-5.7 wt % S alloy can account for the density of the inner core at 328.9 GPa, assuming a linear relationship exists between the density and the nickel and sulfur content.

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  • Density measurements of liquid Fe-Si alloys at high pressure using the sink-float method Reviewed

    Ryuji Tateyama, Eiji Ohtani, Hidenori Terasaki, Keisuke Nishida, Yuki Shibazaki, Akio Suzuki, Takumi Kikegawa

    PHYSICS AND CHEMISTRY OF MINERALS   38 ( 10 )   801 - 807   2011.12

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    The compositional dependence on the density of liquid Fe alloys under high pressure is important for estimating the amount of light elements in the Earth's outer core. Here, we report on the density of liquid Fe-Si at 4 GPa and 1,923 K measured using the sink-float method and our investigation on the effect of the Si content on the density of the liquid. Our experiments show that the density of liquid Fe-Si decreases from 7.43 to 2.71 g/cm(3) non-linearly with increasing Si content (0-100 at%). The molar volume of liquid Fe-Si calculated from the measured density gradually decreases in the compositional range 0-50 at% Si, and increases in the range 50-100 at% Si. It should be noted that the estimated molar volume of the alloys shows a negative volume of mixing between Fe and Si. This behaviour is similar to Fe-S liquid (Nishida et al. in Phys Chem Miner 35:417-423, 2008). However, the excess molar volume of mixing for the liquid Fe-Si is smaller than that of liquid Fe-S. The light element contents in the outer core estimated previously may be an underestimation if we take into account the possible negative value of the excess mixing volume of iron-light element alloys in the outer core.

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  • Phase stability and compression study of (Fe-0.89,Ni-0.11)(3)S up to pressure of the Earth&apos;s core Reviewed

    Takeshi Sakai, Eiji Ohtani, Hidenori Terasaki, Seiji Kamada, Naohisa Hirao, Masaaki Miyahara, Masahiko Nishijima

    AMERICAN MINERALOGIST   96 ( 10 )   1490 - 1494   2011.10

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    An in situ synchrotron powder X-ray diffraction study on (Fe-0.89,Ni-0.11)(3)S was conducted up to 141 GPa and 1590 K. (Fe-0.89,Ni-0.11)(3)S has a tetragonal structure, which is the same structure as Ni-free Fe3S. Fitting a third-order Birch-Murnaghan equation of state to data at ambient temperature yielded a bulk modulus of K-0 = 138.1(7.2) GPa and its pressure derivative K&apos;(0) = 4.5(3) with a zero pressure volume V-0 = 375.67(4) angstrom(3). The density of (Fe-0.89,Ni-0.11)(3)S under the core-mantle boundary condition is 1.7% greater than that of Fe3S. The axial ratio (c/a) of (Fe-0.89,Ni-0.11)(3)S decreases with increasing pressure. The addition of nickel to Fe3S leads to a softening of the c-axis. Assuming that the nickel content of the outer core is about 5 at%, we estimated 12.3-20.8 at% sulfur in the outer core for the given 6-10% density deficit between the outer core and pure iron at 136 GPa.

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  • Static compression of Fe0.83Ni0.09Si0.08 alloy to 374 GPa and Fe0.93Si0.07 alloy to 252 GPa: Implications for the Earth's inner core Reviewed

    Hidetoshi Asanuma, Eiji Ohtani, Takeshi Sakai, Hidenori Terasaki, Seiji Kamada, Naohisa Hirao, Yasuo Ohishi

    EARTH AND PLANETARY SCIENCE LETTERS   310 ( 1-2 )   113 - 118   2011.10

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    The pressure-volume equations of state of iron-nickel-silicon alloy Fe0.83Ni0.09Si0.08 (Fe-9.8 wt.% Ni-4.0 wt.% Si) and iron-silicon alloy Fe0.93Si0.07 (Fe-3.4 wt.% Si) have been investigated up to 374 GPa and 252 GPa, respectively. The present compression data covered pressures of the Earth's core. We confirmed that both Fe0.83Ni0.09Si0.08 and Fe0.93Si0.07 alloys remain in the hexagonal close packed structure at all pressures studied. We obtained the density of these alloys at the pressure of the inner core boundary (ICB), 330 GPa at 300 K by fitting the compression data to the third order Birch-Murnaghan equation of state. Using these density values combined with the previous data for hcp-Fe, hcp-Fe0.8Ni0.2, and hcp-Fe0.84Si0.16 alloys and comparing with the density of the PREM inner core, we estimated the Ni and Si contents of the inner core. The Si content of the inner core estimated here is slightly greater than that estimated previously based on the sound velocity measurement of the hcp-Fe-Ni-Si alloy at high pressure. (C) 2011 Elsevier B.V. All rights reserved.

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  • Density measurement of liquid FeS at high pressures using synchrotron X-ray absorption Reviewed

    Keisuke Nishida, Eiji Ohtani, Satoru Urakawa, Akio Suzuki, Tatsuya Sakamaki, Hidenori Terasaki, Yoshinori Katayama

    AMERICAN MINERALOGIST   96 ( 5-6 )   864 - 868   2011.5

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    The density of liquid iron sulfide (FeS) was measured up to 3.8 GPa and 1800 K using an X-ray absorption method. The compression curve of liquid FeS was fitted using the Vinet equation of state. The isothermal bulk modulus and its temperature and pressure derivatives were determined using a nonlinear least-squares fit. The parameter sets determined were: K(0T) = 2.5 +/- 0.3 GPa at T = 1500 K, (dK(0)/dT)(P) = 0.0036 +/- 0.0003 GPa/K, and (dK(0)/dP)(T) = 24 +/- 2. These results suggest that liquid FeS is more compressible than Fe-rich liquid Fe-S.

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  • Density of carbonated peridotite magma at high pressure using an X-ray absorption method Reviewed

    Tatsuya Sakamaki, Eiji Ohtani, Satoru Urakawa, Hidenori Terasaki, Yoshinori Katayama

    AMERICAN MINERALOGIST   96 ( 4 )   553 - 557   2011.4

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    The density of carbonated peridotite magma was measured up to 3.8 GPa and 2100 K using an X-ray absorption method. A fit of the pressure-density-temperature data to the high-temperature Birch-Murnaghan equation of state yielded the isothermal bulk modulus, K(T0) = 22.9 +/- 1.4 GPa, its pressure derivative, K&apos;(0) = 7.4 +/- 1.4, and the temperature derivative of the bulk modulus (partial derivative K(T)/partial derivative T)(P) = -0.006 +/- 0.002 GPa/K at 1800 K. The bulk modulus of carbonated peridotite magma is larger than that of hydrous peridotite magma. The partial molar volume of CO, in magma under high pressure and temperature conditions was calculated and fit using the Vinet equation of state. The isothermal bulk modulus was K(T0) = 8.1 +/- 1.7GPa, and its pressure derivative was K&apos;0 = 7.2 +/- 2.0 at 2000 K. Our results show that the partial molar volume of CO(2) is less compressible than that of H(2)O, suggesting that, on an equal molar basis, CO(2) is more effective than H(2)O in reducing peridotite melt density at high pressure.

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  • Pressure and temperature dependence of the viscosity of a NaAlSi2O6 melt Reviewed

    Akio Suzuki, Eiji Ohtani, Hidenori Terasaki, Keisuke Nishida, Hiromi Hayashi, Tatsuya Sakamaki, Yuki Shibazaki, Takumi Kikegawa

    PHYSICS AND CHEMISTRY OF MINERALS   38 ( 1 )   59 - 64   2011.1

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    The viscosity of a silicate melt of composition NaAlSi2O6 was measured at pressures from 1.6 to 5.5 GPa and at temperatures from 1,350 to 1,880 degrees C. We employed in situ falling sphere viscometry using X-ray radiography. We found that the viscosity of the NaAlSi2O6 melt decreased with increasing pressure up to 2 GPa. The pressure dependence of viscosity is diminished above 2 GPa. By using the relationship between the logarithm of viscosity and the reciprocal temperature, the activation energies for viscous flow were calculated to be 3.7 +/- 0.4 x 10(2) and 3.7 +/- 0.5 x 10(2) kJ/mol at 2.2 and 2.9 GPa, respectively.

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  • Hydrogenation of FeSi under high pressure Reviewed

    Hidenori Terasaki, Yuki Shibazaki, Tatsuya Sakamaki, Ryuji Tateyama, Eiji Ohtani, Ken-ichi Funakoshi, Yuji Higo

    AMERICAN MINERALOGIST   96 ( 1 )   93 - 99   2011.1

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    Hydrogen is the most abundant element in the solar system, suggesting that hydrogen is one of the plausible light elements in the planetary cores. To investigate the solubility of hydrogen into FeSi and phase relations of the FeSi-H system under high pressure, we performed in situ X-ray diffraction experiments on the FeSi-H and FeSi systems at high pressure and high temperature. Hydrogen starts to dissolve in FeSi (hydrogenation) and form FeSiH(x) with cubic B20 structure above 10 GPa. Hydrogen content (x), estimated from the volume difference between the FeSi-H and FeSi systems, increases from 0.07 to 0.22 with increasing pressure for P &gt; 10 GPa. Comparing the present results with hydrogenation pressure of Fe, presence of Si in metal increases the minimal pressure for H incorporation. Hydrogen, therefore, can only incorporate into the Fe-Si core at the deeper part (P &gt; 10 GPa) in the planetary interior.

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  • Effect of hydrogen on the melting temperature of FeS at high pressure: Implications for the core of Ganymede Reviewed

    Yuki Shibazaki, Eiji Ohtani, Hidenori Terasaki, Ryuji Tateyama, Tatsuya Sakamaki, Taku Tsuchiya, Ken-ichi Funakoshi

    EARTH AND PLANETARY SCIENCE LETTERS   301 ( 1-2 )   153 - 158   2011.1

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    We have carried out in situ X-ray diffraction experiments on the FeS-H system up to 16.5 GPa and 1723 K using a Kawai-type multianvil high-pressure apparatus employing synchrotron X-ray radiation. Hydrogen was supplied to FeS from the thermal decomposition of LiAIH(4), and FeSH(x), was formed at high pressures and temperatures. The melting temperature and phase relationships of FeSH(x) were determined based on in situ powder X-ray diffraction data. The melting temperature of FeSH(x) was reduced by 150-250 K comparing with that of pure FeS. The hydrogen concentration in FeSH(x) was determined to be x = 0.2-0.4 just before melting occurred between 3.0 and 16.5 GPa. 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 H(2)O, and the iron alloy could react with H(2)O (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&apos;s core may be composed of an Fe-S-H system. According to our results, hydrogen dissolved in Ganymede&apos;s core lowers the melting temperature of the core composition, and so today, the core could have solid FeSH(x) inner core and liquid FeH(x)-FeSH(x) outer core and the present core temperature is considered to be relatively low. (C) 2010 Elsevier B.V. All rights reserved.

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  • Hydrogenation of FeSi and FeS alloys at high pressure and high temperature Reviewed

    Hidenori Terasaki, Yuki Shibazaki

    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu   21 ( 3 )   197 - 205   2011

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    Hydrogenation of iron-light element alloys, such as Fe-Si and Fe-S, under high pressure is important to understand the composition and the thermal structure of the planetary cores. Here, we report the hydrogenation pressures of FeSi and FeS, hydrogen solubilities into these alloys and the effect of hydrogen on their phase relations based on in situ X-ray diffraction experiment of FeSi-H and FeS-H systems up to 17 GPa and 2123 K. Hydrogenation of FeSi and FeS occurs at the pressures more than 10 GPa and 3 GPa, respectively. The H solubilities (x) are estimated to be x~0.2-0.3, which are well below compared to the H solubility into pure iron (x~1.0). This small amount of H solubility into the alloys causes only small depressions (150-250 K) of their melting temperaure whereas dissolution of H into Fe decreases its melting temperature significantly. © 2011 The Japan Society of High Pressure Science and Technology.

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  • Liquidus and solidus temperatures of a Fe-O-S alloy up to the pressures of the outer core: Implication for the thermal structures of the Earth’s core. Reviewed

    Terasaki H, Kamada S, Sakai T, Ohtani E, Hirao N, Ohishi Y

    Earth and Planetary Science Letters   304 ( 3-4 )   559 - 564   2011

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  • X-ray imaging of melts and its application to Earth and planetary interior.

    Ohtani, E, Suzuki, A, Terasaki, H, Nishida, K, Shiraishi, R, Tateyama, R

    Photon Factory Activity Report 2009 (KEK Progress Report 2010-4)   27   188   2010.12

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  • Stress relaxation experiments of olivine under conditions of subducted slab in Earth's deep upper mantle Reviewed

    Yu Nishihara, Ken-ichi Funakoshi, Yuji Higo, Noriyoshi Tsujino, Takaaki Kawazoe, Tomoaki Kubo, Akira Shimojuku, Hidenori Terasaki, Norimasa Nishiyama

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   183 ( 1-2 )   164 - 174   2010.11

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    Stress relaxation experiments of olivine were conducted under high-pressure and high-temperature conditions up to 10 GPa and 1273 K using a Kawai-type multi-anvil apparatus. A pre-sintered San Carlos olivine sample rod was inserted between two dense Al2O3 pistons to yield high stress at high-pressure within an octahedral pressure medium. Stress was determined from the two-dimensional diffraction pattern taken using monochromatic X-rays and an imaging-plate, and sample length was determined from an X-ray radiograph. In these experiments, pressure was first increased at room temperature, and then the temperature was increased and kept at 673, 873, 1073, and 1273 K. Four relaxation cycles, in total, were carried out in two experimental runs. The magnitude of deviatoric stress was calculated from five diffraction peaks with the following hkls: 02 1, 1 01, 1 30, I 3 1, and 11 2. The calculated deviatoric stress was significantly different depending on which diffraction peak was used (up to a factor of similar to 2) due to plastic deformation within the polycrystalline sample. The deviatoric stress decreased with increasing temperature in all of relaxation cycles. At given temperatures, the final-state value of deviatoric stress increased with increasing pressure. The upper bound for the plastic strain rate in the final-state was determined to be 10(-7) s(-1) based on a comparison between the total sample length determined from the radiograph and the d-spacings along the piston direction determined from X-ray diffraction. Present results suggest a positive activation volume for the low-temperature rheology of olivine. (C) 2010 Elsevier B.V. All rights reserved.

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  • Stress relaxation experiments of olivine under conditions of subducted slab in Earth's deep upper mantle Reviewed

    Yu Nishihara, Ken-ichi Funakoshi, Yuji Higo, Noriyoshi Tsujino, Takaaki Kawazoe, Tomoaki Kubo, Akira Shimojuku, Hidenori Terasaki, Norimasa Nishiyama

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   183 ( 1-2 )   164 - 174   2010.11

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    Stress relaxation experiments of olivine were conducted under high-pressure and high-temperature conditions up to 10 GPa and 1273 K using a Kawai-type multi-anvil apparatus. A pre-sintered San Carlos olivine sample rod was inserted between two dense Al2O3 pistons to yield high stress at high-pressure within an octahedral pressure medium. Stress was determined from the two-dimensional diffraction pattern taken using monochromatic X-rays and an imaging-plate, and sample length was determined from an X-ray radiograph. In these experiments, pressure was first increased at room temperature, and then the temperature was increased and kept at 673, 873, 1073, and 1273 K. Four relaxation cycles, in total, were carried out in two experimental runs. The magnitude of deviatoric stress was calculated from five diffraction peaks with the following hkls: 02 1, 1 01, 1 30, I 3 1, and 11 2. The calculated deviatoric stress was significantly different depending on which diffraction peak was used (up to a factor of similar to 2) due to plastic deformation within the polycrystalline sample. The deviatoric stress decreased with increasing temperature in all of relaxation cycles. At given temperatures, the final-state value of deviatoric stress increased with increasing pressure. The upper bound for the plastic strain rate in the final-state was determined to be 10(-7) s(-1) based on a comparison between the total sample length determined from the radiograph and the d-spacings along the piston direction determined from X-ray diffraction. Present results suggest a positive activation volume for the low-temperature rheology of olivine. (C) 2010 Elsevier B.V. All rights reserved.

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  • Fe-Mg partitioning between post-perovskite and ferropericlase in the lowermost mantle Reviewed

    Takeshi Sakai, Eiji Ohtani, Hidenori Terasaki, Masaaki Miyahara, Masahiko Nishijima, Naohisa Hirao, Yasuo Ohishi, Nagayoshi Sata

    PHYSICS AND CHEMISTRY OF MINERALS   37 ( 7 )   487 - 496   2010.7

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    Fe-Mg partitioning between post-perovskite and ferropericlase has been studied using a laser-heated diamond anvil cell at pressures up to 154 GPa and 2,010 K which corresponds to the conditions in the lowermost mantle. The composition of the phases in the recovered samples was determined using analytical transmission electron microscopy. Our results reveal that the Fe-Mg partition coefficient between post-perovskite and ferropericlase (K (D) (PPv/Fp) ) increases with decreasing bulk iron content. The compositional dependence of K (D) (PPv/Fp) on the bulk iron content explains the inconsistency in previous studies, and the effect of the bulk iron content is the most dominant factor compared to other factors, such as temperature and aluminum content. Iron prefers ferropericlase compared to post-perovskite over a wide compositional range, whereas the iron content of post-perovskite (X (Fe) (PPv) , the mole fraction) does not exceed a value of 0.10. The iron-rich ferropericlase phase may have significant influence on the physical properties, such as the seismic velocity and electrical conductivity at the core-mantle boundary region.

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  • Density measurement of Fe3C liquid using X-ray absorption image up to 10 GPa and effect of light elements on compressibility of liquid iron Reviewed

    H. Terasaki, K. Nishida, Y. Shibazaki, T. Sakamaki, A. Suzuki, E. Ohtani, T. Kikegawa

    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH   115 ( B6 )   B06207   2010.6

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    Density of liquid iron alloy under high pressure is important to constrain the amount of light elements in the Earth&apos;s core. Density measurement of solid and liquid Fe3C was performed using X-ray absorption image technique up to 9.5 GPa and 1973 K. Density of liquid Fe3C increases from 6.94 g/cm(3) to 7.38 g/cm(3) with a pressure of 3.6-9.5 GPa at 1973 K. The bulk modulus of liquid Fe3C is obtained to be 50 +/- 7 GPa at 1973 K. The effect of carbon on the compressibility of liquid iron is similar to that of sulfur, which significantly decreases the bulk modulus of liquid iron. Since carbon dissolution into liquid iron causes reduction of rho and K-0T, carbon could be excluded from the candidates of alloying light elements in the Earth&apos;s outer core.

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  • Melting of iron-silicon alloy up to the core-mantle boundary pressure: implications to the thermal structure of the Earth&apos;s core Reviewed

    Hidetoshi Asanuma, Eiji Ohtani, Takeshi Sakai, Hidenori Terasaki, Seiji Kamada, Tadashi Kondo, Takumi Kikegawa

    PHYSICS AND CHEMISTRY OF MINERALS   37 ( 6 )   353 - 359   2010.6

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    The melting temperature of Fe-18 wt% Si alloy was determined up to 119 GPa based on a change of laser heating efficiency and the texture of the recovered samples in the laser-heated diamond anvil cell experiments. We have also investigated the subsolidus phase relations of Fe-18 wt% Si alloy by the in-situ X-ray diffraction method and confirmed that the bcc phase is stable at least up to 57 GPa and high temperature. The melting curve of the alloy was fitted by the Simon&apos;s equation, P(GPa)/a = (T (m)(K)/T (0)) (c) , with parameters, T (0) = 1,473 K, a = 3.5 +/- A 1.1 GPa, and c = 4.5 +/- A 0.4. The melting temperature of bcc Fe-18 wt% Si alloy is comparable with that of pure iron in the pressure range of this work. The melting temperature of Fe-18 wt% Si alloy is estimated to be 3,300-3,500 K at 135 GPa, and 4,000-4,200 K at around 330 GPa, which may provide the lower bound of the temperatures at the core-mantle boundary and the inner core-outer core boundary if the light element in the core is silicon.

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  • Density measurement of Fe<inf>3</inf>C liquid using X-ray absorption image up to 10 GPa and effect of light elements on compressibility of liquid iron Reviewed

    H. Terasaki, K. Nishida, Y. Shibazaki, T. Sakamaki, A. Suzuki, E. Ohtani, T. Kikegawa

    Journal of Geophysical Research: Solid Earth   115 ( 6 )   2010.6

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    Density of liquid iron alloy under high pressure is important to constrain the amount of light elements in the Earth's core. Density measurement of solid and liquid Fe3C was performed using X-ray absorption image technique up to 9.5 GPa and 1973 K. Density of liquid Fe3C increases from 6.94 g/cm3 to 7.38 g/cm3 with a pressure of 3.6-9.5 GPa at 1973 K. The bulk modulus of liquid Fe3C is obtained to be 50 ± 7 GPa at 1973 K. The effect of carbon on the compressibility of liquid iron is similar to that of sulfur, which significantly decreases the bulk modulus of liquid iron. Since carbon dissolution into liquid iron causes reduction of ρ and K0T, carbon could be excluded from the candidates of alloying light elements in the Earth's outer core. Copyright © 2010 by the American Geophysical Union.

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  • Phase relationships of the Fe-FeS system in conditions up to the Earth's outer core Reviewed

    Seiji Kamada, Hidenori Terasaki, Eiji Ohtani, Takeshi Sakai, Takumi Kikegawa, Yasuo Ohishi, Naohisa Hirao, Nagayoshi Sata, Tadashi Kondo

    EARTH AND PLANETARY SCIENCE LETTERS   294 ( 1-2 )   94 - 100   2010.5

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    In situ X-ray diffraction experiments in the Fe-FeS system were performed up to 220 GPa and 3300 K using a laser-heated diamond anvil cell. Fe3S and epsilon-Fe coexisted stably up to 220 GPa and 3300 K, and thus, Fe3S is likely to be the stable S-bearing iron alloy under the Earth's core conditions. The solid iron (E-Fe) also contained 7.6(0.8) at.% of sulfur at 86 GPa and 2200 K. The amount of sulfur in the solid iron increased with increasing pressure at the eutectic temperatures. If the sulfur content obtained in this study is extrapolated to the conditions at the inner core, all the sulfur in the solid inner core can be stored in epsilon-Fe.
    The eutectic composition becomes nonsensitive to pressure and seems to be constant around 20 at.% of sulfur at pressures above 40 GPa. The pressure gradient of the melting curve of the Fe-FeS system is 13.4 (0.7) K/GPa. Based on our results of melting relationship, the temperature at the core-mantle boundary should be greater than 2850(100) K, assuming that sulfur is the only light element in the Earth's liquid outer core. (C) 2010 Elsevier B.V. All rights reserved.

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  • Superconducting properties of SmFeAsO1-x prepared under high-pressure condition Reviewed

    Jing Ju, Khuong Huynh, Jun Tang, Zhaofei Li, Masanori Watahiki, Kazumi Sato, Hidenori Terasaki, Eiji Ohtani, Hirotsugu Takizawa, Katsumi Tanigaki

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   71 ( 4 )   491 - 494   2010.4

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    Synthetic conditions such as stoichiometries, temperature and pressure are optimized to achieve a high quality oxygen deficient SmFeAsO0.6 superconductor. Both electric and magnetic measurements show a sharp superconducting transition at about 55 K. Several important physical parameters are deduced. The apparent superconducting gap observed in heat capacity with 2 Delta(o)/k(B)T(c) of 4.57 larger than that of previous fluorine replaced samples indicate that this superconductivity will not strongly conflict with the phonon-mediated BCS mechanism. The mean free length l = 18.8 nm and the coherent length xi = 2.3-3.3 nm show that the superconductivity is in the clean limit. (C) 2009 Elsevier Ltd. All rights reserved.

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  • In situ observation of the formation of intragranular acicular ferrite at non-metallic inclusions in C-Mn steel Reviewed

    Di Zhang, Hidenori Terasaki, Yu-ichi Komizo

    ACTA MATERIALIA   58 ( 4 )   1369 - 1378   2010.2

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    Intragranular acicular ferrite is regarded as a most desirable microstructure feature, in view of its strength and toughness, both in weld metals and in the heat-affected zone. This paper systematically investigated the effect of Ti addition on the evolution of intragranular acicular ferrite in the heat-affected zone of C-Mn steel. We also systematically studied the effects of austenite grain size, alloy content and the characteristic of inclusions on the formation of intragranular acicular ferrite. The nucleation and growth of intragranular acicular ferrite was directly observed by laser scanning confocal microscopy. Subsequently, microscopy analysis was used to quantitatively determine and distinguish the potent and inactive inclusions with respect to the nucleation of intragranular acicular ferrite. Finally, some possible reasons are given to explain the formation of intragranular acicular ferrite in the C-Mn steel. (C) 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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  • Density measurement of silicate melt by X-ray absorption method at high pressures and high temperatures.

    Ohtani, E, Suzuki, A, Terasaki, H, Sakamaki, T, Urakawa, S, Katayama, Y

    SPring-8 User Experiment Report No.23 (2009A)   23   2009A3785   2010.1

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  • Viscosity of lunar high-Ti magma at high pressure.

    Suzuki, A, Ohtani, E, Nishida, K, Tateyama, R, Terasaki, H, Shibazaki, Y, Shiraishi, R, Kikegawa, T

    Photon Factory Activity Report 2008 (KEK Progress Report 2009-3)   26 ( Part B )   181   2010.1

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  • Density measurements of liquid Fe-S at high pressure using sink-float method.

    Tateyama, R, Suzuki, A, Ohtani, E, Terasaki, H, Nishida, K, Shimazaki, Y, Kikegawa, T

    Photon Factory Activity Report 2008 (KEK Progress Report 2009-3)   26 ( Part B )   178   2010.1

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  • Density measurements of liquid FeS at high pressure using X-ray absorption image.

    Nishida, K, Suzuki, A, Ohtani, E, Terasaki, H, Sakamaki, T, Shibazaki, Y, Hayashi, H, Funayama, M, Kikegawa, T

    Photon Factory Activity Report 2008 (KEK Progress Report 2009-3)   26 ( Part B )   179   2010.1

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  • Structure of basaltic magma at high pressures and high temperatures.

    Sakamaki, T, Ohtani, E, Suzuki, A, Terasaki, H, Shibazaki, Y, Hayashi, H, Funakoshi, K, Tateyama, R

    SPring-8 User Experiment Report No.23 (2009A)   23   2009A1661   2010.1

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  • Report on "Global network symposium on earth's dynamics" Reviewed

    Hidenori Terasaki

    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu   20 ( 2 )   181 - 182   2010

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    DOI: 10.4131/jshpreview.20.181

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  • Performance of semi-sintered ceramics as pressure-transmitting media up to 30 GPa Reviewed

    Anton Shatskiy, Konstantin D. Litasov, Hidenori Terasaki, Tomoo Katsura, Eiji Ohtani

    HIGH PRESSURE RESEARCH   30 ( 3 )   443 - 450   2010

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    Semi-sintered MgO-and ZrO(2)-based ceramics are the conventional materials used as a pressure-transmitting medium (PM) for large-volume high-pressure experiments. Our experimental data for both MgO and ZrO(2) provide similar pressure generation efficiency. The major requirement for a PM material is low compressibility. However, our experimental data suggest that semi-sintered types of these ceramics are more compressible than can be expected. For instance, the apparent compressibility of semi-sintered magnesia is 35% and 60% higher than the lattice compressibility of MgO at 15 and 30 GPa, respectively. The difference in lattice and apparent compressibilities of semi-sintered ceramics is most probably caused by a residual porosity. The use of a low-porous pressure medium should be considered as an improvement of pressure generation efficiency of high-pressure apparatuses.

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  • Development of high pressure apparatus for X-ray microtomography at SPring-8 Reviewed

    S. Urakawa, H. P. Terasaki, K. Funakoshi, K. Uesugi, S. Yamamoto

    INTERNATIONAL CONFERENCE ON HIGH PRESSURE SCIENCE AND TECHNOLOGY, JOINT AIRAPT-22 AND HPCJ-50   215   012026-   2010

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    A new high-pressure apparatus has been developed for studies of synchrotron radiation-based X-ray microtomography at SPring-8 of Japan. The high pressure tomography apparatus at SPring-8 is a compact hydraulic press with a 0.8 MN capacity and is equipped with an opposed anvil device. It has two wide windows for X-ray access with a 160-degree opening in the equatorial plane to the compression axis. Radiographs are acquired over 180 degree rotation for reconstruction of 3D image, in which some shadows occur, because the press frame blocks a 20-degree angular region. 3D tomography image computed from radiographs obtained using the high pressure tomography apparatus has a reasonably good quality enough to measure physical properties of materials.

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  • Pressure and temperature dependence of the viscosity of a NaAlSi2O6 melt Reviewed

    Suzuki A, E. Ohtani, H. Terasaki, K. Nishida,H. Hayashi, T. Sakamaki, Y. Shibazaki, K. Funakoshi, T. Kikegawa

    Physics and Chemistry of Minerals   10.1007/s00269-010-0381-4-   2010

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  • Stress measurement under high pressure using Kawai-type multi-anvil apparatus combined with synchrotron radiation Reviewed

    Nishihara Yu, Funakoshi Ken-ichi, Higo Yuji, Terasaki Hidenori, Nishiyama Norimasa, Kubo Tomoaki, Shimojuku Akira, Tsujino Noriyoshi

    JOURNAL OF SYNCHROTRON RADIATION   16 ( 6 )   757 - 761   2009.11

  • Stress measurement under high pressure using Kawai-type multi-anvil apparatus combined with synchrotron radiation Reviewed

    Yu Nishihara, Ken-ichi Funakoshi, Yuji Higo, Hidenori Terasaki, Norimasa Nishiyama, Tomoaki Kubo, Akira Shimojuku, Noriyoshi Tsujino

    JOURNAL OF SYNCHROTRON RADIATION   16   757 - 761   2009.11

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    A system for stress measurement under high pressure has been developed at beamline BL04B1, SPring-8, Japan. A Kawai-type multi-anvil apparatus, SPEED-1500, was used to pressurize polycrystalline KCl to 9.9 GPa in a mechanically anisotropic cell assembly with the KCl sample sandwiched between dense Al2O3 pistons. The variation of deviatoric stress was determined from the lattice distortion measured using two-dimensional X-ray diffraction with monochromatic synchrotron X-rays. The low-pressure B1 phase transformed to the high-pressure polymorph B2 during compression. The deviatoric stress increased with increasing pressure in both the B1 and B2 phases except for the two-phase-coexisting region at a pressure of 2-3 GPa. This new system provides one of the technical foundations for conducting precise rheological measurements at conditions of the Earth's lower mantle.

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  • Hydrogen partitioning between iron and ringwoodite: Implications for water transport into the Martian core Reviewed

    Yuki Shibazaki, Eiji Ohtani, Hidenori Terasaki, Akio Suzuki, Ken ichi Funakoshi

    Earth and Planetary Science Letters   287 ( 3-4 )   463 - 470   2009.10

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    We determined the exchange partition coefficients of hydrogen between solid iron and ringwoodite between 16.6 and 20.9 GPa at temperatures up to 1273 K using a Kawai-type multianvil high-pressure apparatus with synchrotron X-ray radiation at the BL04B1 beamline at SPring-8, Japan. The hydrogen concentration in iron hydride was estimated from the volume expansion of iron caused by hydrogenation determined by in situ X-ray diffractions at high pressure and high temperature, and the water content of ringwoodite in the recovered samples was estimated using the Fourier transform infrared spectroscopy (FTIR). According to our results, the exchange partition coefficients of hydrogen between the solid iron and ringwoodite were almost constant, 26, with pressure between 16.6 and 20.9 GPa and 1273 K. These results revealed that hydrogen was strongly partitioned to metallic iron and that iron hydride formed, coexisting with dry ringwoodite under the experimental pressures. Ringwoodite, found in the Martian core-mantle boundary region, is an important hydrogen reservoir. The pattern of quasi-parallel bands of uniformly magnetized crust with alternating positive and negative polarity measured by the Mars Global Surveyor spacecraft strongly shows that a magnetic field did exist in ancient Mars suggesting a possible plate tectonic activity on ancient Mars. Thus, water could have been transported to the deep Martian interior by hydrous minerals during the plate subduction process and stored in ringwoodite in the deep Martian slabs, as is suggested on the Earth today. Our experiments suggested that hydrogen stored in ringwoodite was absorbed by the Martian core at the Martian core-mantle boundary. Thus, water from the ancient Martian ocean may be stored now in the Martian core. © 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.epsl.2009.08.034

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  • The partitioning of Pt-Re-Os between solid and liquid metal in the Fe-Ni-S system at high pressure: Implications for inner core fractionation Reviewed

    Hiromi Hayashi, Eiji Ohtani, Hidenori Terasaki, Yoshinori Ito

    GEOCHIMICA ET COSMOCHIMICA ACTA   73 ( 16 )   4836 - 4842   2009.8

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    Coupled (186)Os/(188)Os and (187)Os/(188)Os enrichments of plume-derived lavas have been suggested to reflect contributions of materials from the outer core (Brandon et al., 1998). This hypothesis is based on the assumption that the Earth&apos;s liquid outer core has high Pt/Os and slightly high Re/Os ratios as a result of the crystallization of the solid inner core, and shows coupled enrichments in the (186)Os/(188)Os and (187)Os/(188)Os ratios, reflecting the decay of (190)Pt and (187)Re to (186)Os and (187)Os, respectively. Partitioning experiments of Pt-Re-Os between solid and liquid metal were performed at 5-20 GPa and 1250-1400 degrees C, to examine the effects of pressure in the Fe-Ni-S system. The ratios (D(Os)/D(Pt), D(Os)/D(Re)) of measured partition coefficients of Pt, Re and Os are almost constant with increasing pressure. D(Os)/D(Pt) increases significantly, whereas D(Os)/D(Re) decreases, with increasing sulphur content in the liquid metal. On the basis of the present experimental results, it is unlikely that the required Pt-Re-Os fractionation is generated during inner core crystallization, assuming that the light element in the Earth&apos;s core is sulphur. (C) 2009 Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.gca.2009.05.055

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  • Fe-Mg partitioning between perovskite and ferropericlase in the lower mantle Reviewed

    Takeshi Sakai, Eiji Ohtani, Hidenori Terasaki, Naoki Sawada, Yusuke Kobayashi, Masaaki Miyahara, Masahiko Nishijima, Naohisa Hirao, Yasuo Ohishi, Takumi Kikegawa

    AMERICAN MINERALOGIST   94 ( 7 )   921 - 925   2009.7

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    Fe-Mg partitioning between perovskite and ferropericlase in the MgO-FeO-SiO2 system has been studied up to about 100 GPa at around 2000 K using a laser-heated diamond anvil cell (LHDAC). The compositions of both phases were determined by using analytical transmission electron microscopy (ATEM) on the recovered samples. Present results reveal that the Fe-Mg apparent partition coefficient between perovskite and ferropericlase [K-D(Pv/Fp) = ((XFeXMgFp)-X-Pv)/((XMgXFeFp)-X-Pv)] decreases with increasing pressure for a constant FeO of the system, and it decreases with increasing FeO content of ferropericlase. The gradual decrease of K-D(Pv/FP) with increasing pressure is consistent with the spin transition in ferropericlase Occurring in the broad pressure range from 50 to 100 GPa at around 2000 K.

    DOI: 10.2138/am.2009.3123

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  • Density measurement of liquid FeS using X-ray absorption image.

    Nishida, K, Ohtani E, Suzuki, A, Terasaki, H, Sakamaki, T, Shibazaki, Y, Kikegawa, T

    Special Issue of the Review of High Pressure Science and Technology   19   448   2009.7

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  • Density and structure of basaltic magma under high pressure and high temperature.

    Sakamaki, T, Ohtani E, Urakawa, S, Suzuki, A, Terasaki, H, Katayama, Y, Funakoshi, K

    Special Issue of the Review of High Pressure Science and Technology   19   287   2009.7

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  • Density measurement of Fe-C liquid using X-ray absorption image under high pressure.

    Terasaki, H, Nishida, K, Suzuki, A, Ohtani E, Shibazaki, Y, Sakamaki, T, Kikegawa, T

    Special Issue of the Review of High Pressure Science and Technology   19   292   2009.7

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  • Effect of water on post-spinel transition and implication for 660 km seismic discontinuity at the Earth's mantle.

    Ghosh, S, Ohtani E, Suzuki, A, Litasov, K.D, Terasaki, H, Funakoshi, K

    Special Issue of the Review of High Pressure Science and Technology   19   461   2009.7

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  • Viscosity minimum of lunar high-Ti magma at high pressure and high temperature.

    Suzuki, A, Ohtani E, Nishida, K, Terasaki, H, Tateyama, R, Shiraishi, R, Kikegawa, T

    Special Issue of the Review of High Pressure Science and Technology   19   377   2009.7

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  • Hydrogen incorporation to the Earth's core Reviewed

    Hidenori Terasaki, Eiji Ohtani, Takeshi Sakai, Seiji Kamada, Yuki Shibazaki, Hidetoshi Asanuma, Hirao Naohisa, Yasuo Ohishi, Nagayoshi Sata, Tatsuya Sakamaki, Akio Suzuki, Ken-ichi Funakoshi

    GEOCHIMICA ET COSMOCHIMICA ACTA   73 ( 13 )   A1321 - A1321   2009.6

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  • Measurement of sound velocity of Fe-Ni-Si alloys at the ultrahigh pressure.

    Ohtani, E, Sakai, T, Terasaki, H, Murakami, M, Kamada, S, Suzuki, A, Hirao, N

    SPring-8 User Experiment Report No.22 (2008B)   22   2008B1584   2009.6

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  • Viscosities of depolymerized komatiite liquids at high pressure.

    Lesher, C, ODwyer-Brown, L, Terasaki, H, Suzuki, A, Ohtani, E, Yamada, A, Funakoshi, K

    SPring-8 User Experiment Report No.22 (2008B)   22   2008B1319   2009.6

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  • 高温高圧下における鉄-水素-軽元素系の相平衡関係.

    Terasaki, H, Shibazaki, Y, Sakamaki, T, Tateyama, R, Nishitani, N, ODwyer-Brown, L, Lesher, C, Yamada, A, Suzuki, A

    SPring-8 User Experiment Report No.22 (2008B)   22   2008B1439   2009.6

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  • Viscosity of basaltic magma at high pressure.

    Suzuki, A, Ohtani E, Terasaki, H, Sakamaki, T, Shibazaki, Y. Tateyama, R, Funakoshi, K

    SPring-8 User Experimental Report No.22 (2008B)   22   2008B1613   2009.6

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  • Solidus of carbonated peridotite from 10 to 20 GPa and origin of magnesiocarbonatite melt in the Earth&apos;s deep mantle Reviewed

    Sujoy Ghosh, Eiji Ohtani, Konstantin D. Litasov, Hidenori Terasaki

    CHEMICAL GEOLOGY   262 ( 1-2 )   17 - 28   2009.5

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    We have experimentally determined the solidus of an alkali-bearing carbonated peridotite (with 5 wt-% CO(2)) between 10 and 20 GPa. Based on K-deficit in all low-temperature runs we assumed that some melt could be present in the low temperature runs and the true solidus of an alkali-bearing carbonated peridotite is placed below 1200 degrees C. However, based on the disappearance of magnesite and the appearance of the visible quenched melt coexisting with silicate phases, the &apos;apparent&apos; solidus, which may be applicable for peridotite with low alkali contents, was identified. The &apos;apparent&apos; solidus temperature increases from similar to 1380 degrees C at 10 GPa to similar to 1525 degrees C at 15 GPa and the &apos;apparent&apos; solidus curve becomes almost flat from 15 GPa to 20 GPa, where it is located near 1550 degrees C. At 10 GPa, the &apos;apparent&apos; solidus of carbonated peridotite is similar to 550 degrees C lower than the solidus Of CO(2)-free natural anhydrous peridotite. The solidus of the present study was also similar to 120 degrees C lower than the solidus determined by Dasgupta and Hirschmann [Dasgupta, R., Hirschmann, M.M., 2006. Melting in the Earth&apos;s deep upper mantle caused by carbon dioxide. Nature, 440, 659-662.] for natural carbonated peridotite. The drop in the solidus temperature is mainly due to the effect of alkalis (Na(2)O, K(2)O). The melt near the &apos;apparent&apos; solidus has high CO(2) (&gt;40 wt.%) and contains &lt;6.0 wt.% SiO(2), &lt;030 wt.% Al(2)O(3) and &lt;0.25 wt.% TiO(2). The composition of near-solidus partial melt is close to that observed at 6-10 GPa in the CMS-CO(2) and CMAS-CO(2) systems, and natural carbonated peridotite, with some variations in Ca/Mg-ratio. High alkali contents in measured and calculated partial melts are consistent with the compositions of deep-seated fluids observed as inclusions in diamonds and may be consistent with the compositions of parental melt, reconstructed for natural magnesiocarbonatite. We have demonstrated that magnesiocarbonatite-like melt can be generated by partial melting of carbonated peridotite at pressure up to at least 20 GPa. The generation of calciocarbonatite and ferrocarbonatite is unlikely to be possible during melting of carbonated peridotite in the deep mantle. (C) 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.chemgeo.2008.12.030

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  • In situ measurement of interfacial tension of Fe-S and Fe-P liquids under high pressure using X-ray radiography and tomography techniques Reviewed

    H. Terasaki, S. Urakawa, K. Funakoshi, N. Nishiyama, Y. Wang, K. Nishida, T. Sakamaki, A. Suzuki, E. Ohtani

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   174 ( 1-4 )   220 - 226   2009.5

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    Interfacial tension is one of the most important properties of the liquid iron alloy that controls the core formation process in the early history of the Earth and planets. In this study, we made high-pressure X-ray radiography and micro-tomography measurements to determine the interfacial tension between liquid iron alloys and silicate melt using the sessile drop method. The measured interfacial tension of liquid Fe-S decreased significantly (802-112 mN/m) with increasing sulphur content (0-40 at%) at 1.5 GPa. In contrast, the phosphorus content of Fe had an almost negligible effect on the interfacial tension of liquid iron. These tendencies in the effects of light elements are consistent with those measured at ambient pressure. Our results suggest that the effect of sulphur content on the interfacial tension of liquid Fe-S (690 mN/m reduction with the addition of 40 at% S) is large compared with the effect of temperature (similar to 273 mN/m reduction with an increase of 200 K). The three-dimensional structure of liquid Fe-S was obtained at similar to 2 GPa and 1373-1873 K with a high-pressure tomography technique. The Fe-S droplet was quite homogeneous when evaluated in a slice of the three-dimensional image. (C) 2009 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.pepi.2009.01.004

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  • Density measurements of liquid FeS at high pressure using X-ray absorption image.

    Nishida, K, Suzuki, A, Terasaki, H, Ohtani, E, Sakamaki, T, Shibazaki, Y, Hayashi, H, Funayama, M, Kikegawa, T

    Photon Factory Activity Report 2007   25   198   2009.2

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  • Percolative core formation model in planet interiors Reviewed

    Hidenori Terasaki

    Japanese Magazine of Mineralogical and Petrological Sciences   38 ( 1 )   9 - 12   2009

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    The percolation of liquid iron alloy through crystalline silicates potentially played an important role during core formation in planetary bodies of the early solar system. In order to test the feasibility of percolative core formation, the effects of pressure, composition and mineral assemblage on the dihedral angle between Fe-O-S liquid and mantle minerals have been investigated from 1.5 to 23.5 GPa. Texturally-equilibrated dihedral angles increase from 54 to 106° over this pressure range. The dihedral angle increases with pressure and closely related to the oxygen content of Fe-O-S phase, which decreases with increasing pressure, because oxygen reduces the interfacial energy of Fe-S melt. However, the effect of mineral assemblage on the dihedral angle seems to be negligible. Therefore, percolation is likely to have been the dominant core formation mechanism in small relatively-oxidised planetary bodies with a radius less than abogt 1300 km.

    DOI: 10.2465/gkk.38.9

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  • Physical properties of liquid iron-alloy under high pressure: Implications to planetary core Reviewed

    Hidenori Terasaki

    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu   19 ( 2 )   156 - 162   2009

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    Physical properties of liquid iron-alloy under high pressure control the planetary core formation, evolution and its dynamics. In this review paper, high pressure behaviors of some physical properties (viscosity, wetting property and interfacial tension) are discussed and applied to the planetary core. The viscosities of Fe-S and Fe-C liquids measured using X-ray radiography falling sphere method up to 16 GPa show low viscosity values (∼10 mPa-s) and the activation volume of viscous flow is also very small (∼1.5 cm 3/mol). The influence of light elements on the viscosity and the activation volume has only a minor contribution. Dihedral angle, i.e. wetting property of Fe-S-O liquid among mantle minerals is mainly controlled by an interfacial energy of liquid iron-alloy and not by that of solid phase. The effect of light elements on interfacial tension of Fe-S and Fe-P liquids measured using sessile drop method depends on element species. Sulphur corresponds to a surface-active element. The trend observed at high pressure is quite consistent with those at ambient pressure.

    DOI: 10.4131/jshpreview.19.156

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  • Solidus of Carbonated Peridotite and petrogenesis of Magnesio-carbonatite in the Earth’s Upper Mantle and Transition Zone Reviewed

    Ghosh, S, Ohtani, E, K. Litasov, H. Terasaki

    Chemical Geology   2009

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  • In situ X-ray experiment on the structure of basaltic magma under high pressure and high temperature.

    Sakamaki, T, Suzuki, A, Ohtani, E, Terasaki, H, Funakoshi, K

    SPring-8 User Experiment Report No.21 (2008A)   21   2008A1118   2008.11

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  • 高温高圧X線その場観察実験による鉄-マントル鉱物間の水素分配;火星の核-マントル境界における水素挙動の解明.

    Terasaki, H, Shibazaki, Y, Ohtani, E, Suzuki, A, Sakamaki, T, Ghosh, S, Nishida, K

    SPring-8 User Experiment Report No.21 (2008A)   21   2008A1145   2008.11

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  • X線吸収法によるペリドタイトマグマの密度測定.

    Ohtani, E, Suzuki, A, Terasaki, H, Sakamaki, T, Urakawa, S, Katayama, Y, Hayashi, H, Nakano, Y

    SPring-8 User Experiment Report No.21 (2008A)   21   2008A3722   2008.11

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  • The effect of sulfur content on density of the liquid Fe-S at high pressure Reviewed

    K. Nishida, H. Terasaki, E. Ohtani, A. Suzuki

    PHYSICS AND CHEMISTRY OF MINERALS   35 ( 7 )   417 - 423   2008.8

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    The density of liquid Fe-S was measured at 4 GPa and 1,923 K using a sink/float method with a composite density marker. The density marker consisted of a Pt rod core and an Al(2)O(3) tube surrounding. The uncertainty in the density of the composite marker is much smaller than that of the composite sphere, which had been used in previous density measurements. The density of liquid Fe-S decreases nonlinearly with increasing sulfur content at 4 GPa and 1,923 K. This tendency is consistent with the results measured at ambient pressure. The molar volume of FeS calculated from the measured density gradually increases with sulfur content. The excess molar volume from ideal mixing of Fe and S at 4 GPa was negative value. The new method proposed here is applicable to the density measurement of other Fe alloys at high pressure. The tendency of the molar volume and the excess molar volume with sulfur content at ambient pressure is consistent with these at high pressure at least up to 4 GPa. The excess molar volume at high pressure is essential for estimating the amount of light elements in the outer core.

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  • Percolative core formation in planetesimals Reviewed

    Hidenori Terasaki, Daniel J. Frost, David C. Rubie, Falko Langenhorst

    EARTH AND PLANETARY SCIENCE LETTERS   273 ( 1-2 )   132 - 137   2008.8

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    The percolation of liquid iron alloy through crystalline silicates potentially played an important role during core formation in small bodies of the early solar system, such as asteroids and planetesimals. This is because heat production by radioactive decay of Al-26 and Fe-60. which is believed to be the main heat source in early-formed small planetary bodies, will initially cause Fe-S melts to form, well before the silicates start to melt. In order to test the feasibility of percolation, the effect of pressure on the dihedral angle between Fe-O-S liquid and olivine has been investigated from 1.5 to 5.0 GPa, a pressure range that is relevant for the interiors of large asteroids. Texturally-equilibrated dihedral angles increase from 54 degrees to 98 degrees over this pressure range. The dihedral angle reaches the critical value of 60 degrees at 2-3 GPa depending on the olivine composition (Fe#). This change in dihedral angle is related to the oxygen content of Fe-O-S phase, which decreases with increasing pressure, because oxygen dissolved in the melt reduces the Fe-S melt/olivine interfacial energy. These results show that Fe-O-S liquid can form an interconnected network and percolate through silicate aggregates under conditions of high oxygen fugacity and low pressure, even when the melt fraction is small. Therefore, percolation is likely to have been the dominant core formation mechanism in small relatively-oxidised planetary bodies with a radius less than about 1300 km. (C) 2008 Elsevier B.V. All rights reserved.

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  • Phase relations of Fe-Si alloy up to core conditions: Implications for the Earth inner core Reviewed

    Hidetoshi Asanuma, Eiji Ohtani, Takeshi Sakai, Hidenori Terasaki, Seiji Kamada, Naohisa Hirao, Nagayoshi Sata, Yasuo Ohishi

    GEOPHYSICAL RESEARCH LETTERS   35 ( 12 )   L12307   2008.6

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    X-ray diffraction experiments were conducted to 257 GPa and high temperature in situ on an iron-silicon alloy containing 3.4 wt% silicon, a candidate for the Earth's inner core forming material. The results revealed that fcc and hcp phases coexist up to 104 GPa. A single hcp phase is stable at higher pressures at least up to 3600 K at 242 GPa and to 2400 K at 257 GPa. Dissolution of silicon in the liquid outer core following reaction with the silicate mantle during core formation strongly suggests the existence of silicon in the solid inner core. Our results revealed that the iron-3.4 wt% silicon alloy in the inner core is likely to possess an hcp structure, which can explain the inner core anisotropy observed in seismology.

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  • Interfacial tension measurement of Ni-S liquid using high-pressure X-ray micro-tomography Reviewed

    Hidenori Terasaki, Satoru Urakawa, Ken-ichi Funakoshi, Yanbin Wang, Yuki Shibazaki, Takeshi Sanehira, Yasuhiro Ueda, Eiji Ohtani

    HIGH PRESSURE RESEARCH   28 ( 3 )   327 - 334   2008

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    High-pressure, high-temperature X-ray tomography experiments have been carried out using a large volume toroidal cell, which is optimized for interfacial tension measurements. A wide anvil gap, which corresponds to a field of view in the radiography imaging, was successively maintained to high pressures and temperatures using a composite plastic gasket. Obtained interfacial tensions of Ni-S liquid against Na, K-disilicate melt, were 414 and 336 mN/m at 1253 and 1293 K, respectively. Three-dimensional tomo-graphy images revealed that the sample had an irregular shape at the early stage of melting, suggesting either non-equilibrium in sample texture and force balance or partial melting of surrounding silicate. This information cannot always be obtained from two-dimensional radiographic imaging techniques. Therefore, a three-dimensional tomography measurement is appropriate for the precise interfacial measurements.

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  • In situ X-ray diffraction study of Hydrogen partitioning between iron and mantle minerals under high pressure and temperature; Implications to Hydrogen behavior at the Martian core-mantle boundary

    Terasaki, H, Shibazaki Y, Ohtani E, Suzuki, A, Sakamaki T, Ghosh S, Nishida K

    SPring-8 User Experimental Report   2008

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  • Preliminary in situ determination of the solvus in the Fe-FeO system at 2-5 GPa up to 2800 K

    Asahara, Y, D.J. Frost, D.C. Rubie, A. Saikia, H. Terasaki, E. Ohtani, K. Funakoshi, T. Matsuzaki

    Annual report 2007 of Bayerisches Geoinstitut   2008

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  • Study of high pressure phases of iron-nickel-silicon alloy at multi-megabar pressure and high temperature

    Ohtani, E, Asanuma, H, Terasaki, H, Sakai, T, Kamada, S, Sawada, N, Kondo, T, Hirao, N

    SPring-8 User Experimental Report, 2008A.   2008

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  • Phase relation of Fe-Ni-S ternary system at the core pressure and temperature

    Sakai, T, Kamada, S, Terasaki, H, Ohtani, E, Asanuma, H, Hirao, N

    SPring-8 User Experimental Report, 2008A.   2008

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  • In situ observation and determination of liquid immiscibility in the Fe-O-S melt at 3 GPa using a synchrotron X-ray radiographic technique Reviewed

    Kyusei Tsuno, Hidenori Terasaki, Eiji Ohtani, Akio Suzuki, Yuki Asahara, Keisuke Nishida, Tatsuya Sakamaki, Ken-Ichi Funakoshi, Takumi Kikegawa

    GEOPHYSICAL RESEARCH LETTERS   34 ( 17 )   L17303-L17303-6   2007.9

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    We have performed in situ experiments on liquid immiscibility in Fe-O-S melts at 3 GPa and up to 2203 K using a synchrotron X-ray radiographic technique. The difference between immiscible melts and a miscible melt can be clearly observed in radiographs. The immiscibility gap of the Fe-O-S melt shrinks with increasing temperature at 3 GPa. Two separated phases appeared from a miscible melt during quenching. Without in situ observations, the two phases observed in quench textures would be interpreted as either quench products from primary immiscible melts at high temperature, or those exsolved from a homogeneous melt to immiscible melts passing through the stability field of immiscible melts during quenching. In situ measurements are required in order to determine the immiscibility gap of the liquid Fe with light element(s). Our results have important implications for the formation and chemical composition of the cores of Earth and Mars.

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  • Effect of structural transitions on properties of high-pressure silicate melts: Al-27 NMR, glass densities, and melt viscosities Reviewed

    Jeffrey R. Allwardt, Jonathan F. Stebbins, Hidenori Terasaki, Lin-Shu Du, Daniel J. Frost, Anthony C. Withers, Marc M. Hirschmann, Akio Suzuki, Eiji Ohtani

    AMERICAN MINERALOGIST   92 ( 7 )   1093 - 1104   2007.7

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    The densities and viscosities of silicate melts depend strongly on pressure, in part because of potentially measurable structural rearrangements. In an attempt to further understand these changes and how they affect macroscopic properties, we have used Al-27 MAS NMR to determine the coordination of the Al cations in a series of alummosilicate glasses quenched from melts at pressures of 2 to 8 GPa, have measured the glass densities, and have applied an in-situ falling sphere method to measure melt viscosities at high pressure. Spectra from these four- and five-component glasses show increasing Al coordination with increasing pressure and with increasing average field strength of the modifier cation, as was previously reported for simpler compositions. These data also indicate that when multiple modifier cations are present (e.g., Ca and K), the Al coordination is lower than what would be expected from linear combinations of the appropriate alummosilicate end-members.
    The viscosity of Ca3Al2Si6O18 melts, measured using a falling sphere method that combines multianvil techniques with synchrotron X-ray radiography, may reach a minimum at a pressure below 6 GPa. A quasi-thermodynamic approach using equilibrium constants for the reactions that generate high-coordinated Al suggests that this pressure may be related to a maximum in the concentration of five-coordinated Al. These results further support the concept that pressure-induced network structural transitions have direct implications for the macroscopic properties of high-pressure melts.

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  • Interconnectivity of Fe-O-S liquid in polycrystalline silicate perovskite at lower mantle conditions Reviewed

    Hidenori Terasaki, Daniel J. Frost, David C. Rubie, Falko Langenhorst

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   161 ( 3-4 )   170 - 176   2007.5

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    An important aspect of planetary core formation concerns whether interconnectivity of liquid metal can occur in crystalline silicates, which at low melt fractions requires that the dihedral angle between the two phases is &lt; 60 degrees. [Shannon, M.C., Agee, C.B., 1998. Percolation of core melts at lower mantle conditions. Science 280, 1059-1061] previously reported that dihedral angles in mantle assemblages decrease from 108 degrees at upper mantle conditions to 71 degrees at lower mantle conditions as a result of mineral phase transformations. Furthermore [Terasaki, H., Frost, D.J., Rubie, D.C., Langenhorst, F., 2005. The effect of oxygen and sulphur on dihedral angle between Fe-O-S melt and solid silicates under high pressure: implications for Martian core formation. Earth Planet. Sci. Lett. 232, 379-392] observed that dihedral angles between Fe-O-S liquid and solid silicates (olivine and ringwoodite) decrease to 66 degrees at high oxygen and sulphur fugacities. Therefore, it may be possible for liquid metal to form an interconnected network at lower mantle conditions at high 0 and S fugacities. We have investigated the effects of the FeO content of perovskite, with Mg/(Mg + Fe) (Mg#) = 0.84-1.00, on the dihedral angle up to 23.5 GPa and 2223 K. Observed dihedral angles decrease significantly from 102 degrees to 79 degrees with increasing FeO content of the perovskite phase. This tendency is in good agreement with our previous dihedral angle results for olivine and ringwoodite. The dihedral angle is, however, still higher than the critical value of 60 degrees at pressures of the top of the lower mantle, i.e. at this depth efficient core-mantle differentiation is not possible by a percolation mechanism. (c) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.pepi.2007.01.011

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  • Post-stishovite phase transformation in hydrous oceanic crust and seismic reflectors in the lower mantle

    Litasov, K, Ohtani, E, Terasaki, H, Suzuki, A

    Spring-8 User Experimental Report   2006B1230   2007.4

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  • Determination of the phase boundary and the reaction kinetics of the post-spinel phase transition in the MgO-SiO2-H2O system

    Ohtani E, Ghosh S, Suzuki A, Litasov K, Terasaki H, Ozawa S

    Spring-8 User Experimental Report   2007A1701   2007.4

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  • Reaction between metallic iron and elta-AlOOH at the core-mantle boundary

    Ohtani, E, Kondo, T, Terasaki, H, Sano, A, Hirao, N

    Spring-8 User Experimental Report   2006B1094   2007.4

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  • In situ observation of liquid immiscibility of Fe-O-S liquid using X-ray radiography under high pressure

    Terasaki, H, Ohtani, E, Suzuki, A, Tsuno, K, Asahara, Y, Sakamaki, T, Ozawa, S, Shibazaki, Y, Ghosh, S, Litasov, K, Nishida, K, Funakoshi, K

    Spring-8 User Experimental Report   2007A1096   2007.4

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  • Search for post delta-AlOOH at multi-megabar conditions

    Ohtani E, Sano A, Terasaki H, Sakai T, Hirao N, Asanuma H

    Spring-8 User Experimental Report   2007A2090   2007.4

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  • Immiscible two-liquid regions in the Fe-O-S system at high pressure: Implications for planetary cores Reviewed

    Kyusei Tsuno, Eiji Ohtani, Hidenori Terasaki

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   160 ( 1 )   75 - 85   2007.1

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    We have determined phase relations in the Fe-O and Fe-O-S systems in the range of 15-21 GPa and 1825-2300 degrees C. Below the liquidus temperatures, solid FeO and metallic liquids are observed in both the Fe-O and the Fe-O-S systems. An immiscible two-liquid region exists in the Fe-O binary system in the pressure range investigated, and the immiscibility gap between Fe-rich metallic liquid and FeO-rich ionic liquid does not greatly change with either pressure or temperature. On the other hand, an immiscible two-liquid region in the Fe-O-S ternary system narrows significantly with increasing pressure at constant temperature and vice versa, and it almost disappears at 21 GPa, and 2300 degrees C. Immiscible two-liquid regions are thus not expected to exist in the Fe-O-S system in the Earth's core, suggesting that both oxygen and sulfur can be incorporated into the core. Our results are consistent with a geochemical model for the core containing 5.8 wt.% oxygen and 1.9 wt.% sulfur as proposed by McDonough and Sun [McDonough, W.F., Sun, S.-S., 1995. The composition of the Earth. Chem. Geol. 120, 223-253]. (c) 2006 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.pepi.2006.09.004

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  • メガバール領域におけるFe-Ni合金と含水相δ-AlOOHの反応:コア-マントル境界における水素の行方

    Terasaki, H, Ohtani, E, Sakai, T, Kamada, S, Asanuma, H, Sano, A, Hirao, N

    Spring-8 User Experimental Report,   2007A1731   2007

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  • Equation of state and phase relation of FeNiSi alloy to megabar pressure

    Ohtani E, Asanuma H, Sakai T, Terasaki H, Kondo T, Hirao N

    Spring-8 User Experimental Report   2007A1678   2007

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  • In-situ determination of solvus in the Fe-FeO system at high temperatures and high pressures

    Asahara, Y, Frost, D, Rubie, D, Terasaki, H, Tsuno, K, Nishida, K, Saikia, A, Ohtani, E

    Spring-8 User Experimental Report   2006B1313   2007

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  • Influence of water on phase transitions in forsterite and olivine compositions with implication to seismic discontinuities in the Earth's mantle

    Litasov, K, Ohtani, E, Ghosh, S, Terasaki, H, Suzuki, A

    Spring-8 User Experimental Report   2007A1701   2007

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  • X-ray diffraction study of basaltic liquid at high pressure and high temperature

    Sakamaki, T, Suzuki, A, Ohtani, E, Terasaki, H, Nishida

    Spring-8 User Experimental Report   2007A1095   2007

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  • Effect of pressure on the viscosity of Fe-S and Fe-C liquids up to 16 GPa Reviewed

    H. Terasaki, A. Suzuki, E. Ohtani, K. Nishida, T. Sakamaki, K. Funakoshi

    GEOPHYSICAL RESEARCH LETTERS   33 ( 22 )   L22307 - L22307   2006.11

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    The viscosity of liquid Fe78S22 was measured up to 16 GPa and 1723 K using a high-speed CCD camera system ( 125 frames/s maximum). In order to prevent a chemical reaction between the sample and a Re viscosity marker sphere, the Re spheres were coated with alumina to a thickness of 1 - 2 mu m. The measured viscosity coefficients were 3.2 - 8.5 mPa-s and the activation volume was estimated to be 1.46 cm(3)/mol. The viscosity of liquid Fe86C14 was also measured up to 4.5 GPa and 1843 K. The viscosity coefficients were 3.8 - 6.3 mPa-s. There was no large difference in viscosity coefficient and activation volume between the Fe-S and Fe-C eutectic liquids in the range of measurement. Viscosities of Fe-S and Fe-C eutectic liquids are likely to remain low in the planetary interior.

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  • Interaction between iron and post-perovskite at core-mantle boundary and core signature in plume source region Reviewed

    Takeshi Sakai, Tadashi Kondo, Eiji Ohtani, Hidenori Terasaki, Noriaki Endo, Toshiko Kuba, Toshiaki Suzuki, Takumi Kikegawa

    GEOPHYSICAL RESEARCH LETTERS   33 ( 15 )   10.1029/2006GL026868-   2006.8

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    Interaction between the lower mantle and core is essential for understanding the nature of D '' layer at the core-mantle boundary (CMB). Here, we report the reaction between post-perovskite (PPv) and metallic iron under the condition of the CMB, for example, 139 GPa and 3000 Kelvin. Analytical transmission electron microscope ( ATEM) analysis revealed that significant amount of oxygen up to 6.3 weight percent (wt.%) and silicon up to 4.0 wt.% can be dissolved into molten iron. The dihedral angle between PPv and molten iron is 67 degrees. Thus, a small amount of core metal of about 2 volume percent (vol.%) can be trapped without separation in the PPv region at the CMB. The amount of core metal trapped by this mechanism can produce the isotopic signature of the outer core in the plume source at the base of the lower mantle.

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  • High-temperature viscosity measurements of hydrous albite liquid using in-situ falling-sphere viscometry at 2.5 GPa Reviewed

    BT Poe, C Romano, C Liebske, DC Rubie, H Terasaki, A Suzuki, K Funakoshi

    CHEMICAL GEOLOGY   229 ( 1-3 )   2 - 9   2006.5

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    In-situ failing-sphere viscometry using shadow radiography in a multianvil apparatus was conducted on a series of samples along the NaAlSi3O8-H2O join up to 2.8 wt.% H2O at the Spring-8 synchrotron radiation facility (Hyogo, Japan). This allowed us to determine viscosities normally too low to be measured at ambient pressure for hydrous silicate melts at high temperatures due to rapid devolatilization. Pressure was fixed at 2.5 GPa for all experiments allowing us to gauge the effect of chemical composition on viscosity. In particular, the series of samples allowed us to vary the melt's degree of polymerization while maintaining a constant At to Si ratio. Our results show that, for all samples, viscosity decreases as a function of pressure between 1 atm and 2.5 GPa at 1550 degrees C, indicating that the pressure anomaly can still be observed as depolymerization of the melt increases from nominally 0 (dry albite liquid) to NBO/T=0.8 (assuming water speciation entirely as hydroxyl groups at experimental conditions). We also find that the magnitude of the decrease in viscosity over this pressure interval does not appear to be dependent on the amount of water in the melt (i.e., NBO/T). An explanation for this behavior might be that the molar volume, at least over this limited compositional range, is nearly constant and the effects of compression of these melts, though different in degree of polymerization, are similar. (c) 2006 Published by Elsevier B.V.

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  • 高圧下における静滴法を用いたFe-S融体の界面エネルギー測定

    Terasaki H, Ohtani E, Suzuki A, Tsuno K, Sakamaki T, Nishida K, Asanuma H, Litasov K, Secco R, Yu X

    Spring-8 User Experimental Report   2006A   2006

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  • Influence of water on phase transition in olivine and peridotite compositions with implication to 410- and 520-km discontinuity in the transition zone

    Litasov K, Ohtani E, Suzuki A, Terasaki H

    Spring-8 User Experimental Report   2006A   2006

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  • Radiography method for the density measurement of basaltic magma at high pressure and high temperature

    Suzuki A, Ohtani E, Terasaki H, Sakamaki T, Nishida K

    Spring-8 User Experimental Report   2006A   2006

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  • Viscosity measurement of molten Fe-S-O alloy above 20 GPa

    Ohtani E, Terasaki H, Suzuki A, Tsuno K, Nishida K, Sakamaki T, Yu X, Secco R

    Spring-8 User Experimental Report   2006A   2006

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  • Viscosity of peridotite liquid up to 13 GPa: Implications for magma ocean viscosities Reviewed

    C Liebske, B Schmickler, H Terasaki, BT Poe, A Suzuki, K Funakoshi, R Ando, DC Rubie

    EARTH AND PLANETARY SCIENCE LETTERS   240 ( 3-4 )   589 - 604   2005.12

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    The viscosity of synthetic peridotite liquid has been investigated at high pressures using in-situ falling sphere viscometry by combining a multi-anvil technique with synchrotron radiation. We used a newly designed capsule containing a small recessed reservoir outside of the hot spot of the heater, in which a viscosity marker sphere is embedded in a forsterite+enstatite mixture having a higher solidus temperature than the peridotitc. This experimental setup prevents spheres from falling before a stable temperature above the liquidus is established and thus avoids difficulties in evaluating viscosities from velocities of spheres falling through a partially molten sample.
    Experiments have been performed between 2.8 and 13 GPa at temperatures ranging from 2043 to 2523 K. Measured viscosities range from 0.019 (+/- 0.004) to 0.13 (+/- 0.02) Pa s. At constant temperature, viscosity increases with increasing pressure up to similar to 8.5 GPa but then decreases between similar to 8.5 and 13 GPa. The change in the pressure dependence of viscosity is likely associated with structural changes of the liquid that occur upon compression. By combining our results with recently published 0.1 MPa peridotite liquid viscosities [D.B. Dingwell, C. Courtial, D. Giordano, A. Nichols, Viscosity of peridotite liquid, Earth Planet. Sci. Lett. 226 (2004) 127-138.], the experimental data can be described by a non-Arrhenian, empirical Vogel-Fulcher-Tamman equation, which has been modified by adding a term to account for the observed pressure dependence of viscosity. This equation reproduces measured viscosities to within 0.08 log(10)-units on average. We use this model to calculate viscosities of a peridotitic magma ocean along a liquid adiabat to a depth of similar to 400 km and discuss possible effects on viscosity at greater pressures and temperatures than experimentally investigated. (C) 2005 Elsevier B.V. All rights reserved.

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  • Viscosity of silicate melts in CaMgSi(2)O(6)-NaAlSi(2)O(6) system at high pressure Reviewed

    A Suzuki, E Ohtani, H Terasaki, K Funakoshi

    PHYSICS AND CHEMISTRY OF MINERALS   32 ( 2 )   140 - 145   2005.6

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    In situ X-ray viscometry of the silicate melts was carried out at high pressure and at high temperature. The viscosity of the silicate melts in the diopside(Di)-jadeite(Jd) system was determined in the pressure range from 1.88 GPa to 7.9 GPa and in the temperature range from 2,003 K to 2,173 K. The viscosity of the Di 25%-Jd 75% melt decreases continuously to 5.0 GPa, whereas the viscosity of the Di 50%-Jd 50% melt increases over 3.5 GPa. The viscosity of the Di50%-Jd 50% melt reaches a minimum around 3.5 GPa. Since the amounts of silicon in the two melts are the same, the difference in the pressure dependence of the viscosity may be controlled by another network-forming element, i.e., aluminum. The difference in the pressure dependence of the viscosities in the melts with two intermediate compositions in the Di-Jd system is estimated to be due to the difference in the melt structures at high pressures and high temperatures.

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  • The effect of oxygen and sulphur on the dihedral angle between Fe-O-S melt and silicate minerals at high pressure: Implications for Martian core formation Reviewed

    H Terasaki, DJ Frost, DC Rubie, F Langenhorst

    EARTH AND PLANETARY SCIENCE LETTERS   232 ( 3-4 )   379 - 392   2005.4

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    A crucial factor in the investigation of terrestrial planet core formation is whether or not a liquid iron-alloy can segregate from a solid silicate matrix. The interconnectivity of a core-forming liquid depends on the dihedral angle between liquid iron alloy and crystalline silicates at low melt fractions. Recent experimental studies at ambient pressure have implied that liquid iron-alloy can wet an olivine matrix under conditions of high oxygen and sulphur fugacities. We have examined the effects of varying sulphur and oxygen contents on the dihedral angle between liquid iron-alloy and crystalline silicates up to 20 GPa. The compositions studied are applicable to core formation on both the Earth and Mars and the pressure range investigated is applicable to over 80% of the depth of the entire Martian mantle. Dihedral angles in texturally equilibrated samples decrease with increasing sulphur content and also decrease significantly with increasing FeO content of silicates. Increasing the FeO content of silicates results in an increase in both the oxygen fugacity and oxygen solubility in the Fe-S, melt. Oxygen is found to have a larger effect in reducing the dihedral angle than sulphur. The dihedral angle between metallic melt and silicate crystals in the Martian mantle would have been closer to the wetting boundary of 60 degrees than in the Earth's interior, but it would be still too large (0 &gt; 60 degrees) to allow percolation to occur to completion. These results show that melting of the silicate mantle is required to obtain complete metal-silicate separation, which therefore supports a magma ocean scenario for core formation on both Mars and Earth. (c) 2005 Elsevier B.V. All rights reserved.

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  • Density of metallic liquid by X-ray radiography method at high pressure Reviewed

    Suzuki Akio, Ohtani Eiji, Terasaki Hidenori

    Abstracts of Papers Presented at the Annual Meeting of The Japanese Association of Mineralogists, Petrologists and Economic Geologists   2005 ( 0 )   92 - 92   2005

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  • Phase relations in peridotite-CO2 system to 20 GPa Reviewed

    Ghosh Sujoy, Ohtani Eiji, Litasov Konstantin, Suzuki Akio, Terasaki Hidenori

    Abstracts for Annual Meeting of the Mineralogical Society of Japan   2005 ( 0 )   13 - 13   2005

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    Carbon dioxide and water are the most important volatile constituents in the Earth and they produce drastic changes in the melting phase relations and partial melt composition of the mantle peridotites. Study of the peridotite-CO2 system is closely related to petrogenesis of kimberlite and diamond. There are a few high pressure mineral inclusions (i.e. majorite garnet and Ca & Mg perovskite) in diamond which suggest that kimberlites may be originated from the transition zone and lower mantle. Several experimental petrologists have studied the kimberlite and basalt-CO2 systems, however the phase relations and melt compositions in the CO2-bearing peridotite at high pressures are poorly constrained. Simplified peridotite-CO2 system (like CMS or CMAS) has been studied at pressures up to 12 GPa (Canil and Scarfe, 1990), whereas complex peridotite-CO2 systems have investigated only at lower pressures (up to 4 GPa, e.g. Wendlandt and Mysen, 1980). In this work we report the results on the phase relations and melt compositions of a model peridotite-CO2 system determined at 10-20 GPa and temperature range from 1200 to 2100oC.Our results show that solidus of carbonated peridotite is consistent with low-pressure data for CMAS-CO2 system. Liquidus phase at 10-20 GPa is majorite garnet. At 10-15 GPa, crystallization sequence with decreasing temperature is garnet, olivine and clinoenstatite. Magnesite is the most important CO2-rich phase stable in peridotite and clinoenstatite is an important phase in carbonated peridotite at 10-15 GPa.The partial melts formed by 10-25% melting at 10-20 GPa has high MgO (26-34 wt.%) and FeO (7.0-10.4 wt.%) and low SiO2 (18-36 wt.%) and Al2O3 (0.5-1.3 wt.%) contents. It contains also 6-12 wt.% CaO, 0.6-2.0 wt.% Na2O and 0.1-0.3 wt.% K2O. The CO2 contents in the melts are 14-32 wt.%. SiO2-poor composition of partial melts is different to the results for melting of anhydrous or water-bearing peridotite. Partial melting of hydrous peridotite produce SiO2-rich melts, which can be related to komatiite magmas (e.g. Litasov and Ohtani, 2002). The composition of low degree partial melts (10%) in present experiments is close to magnesiocarbonatites, whereas higher degree melting (20-25%) produce melts, which is close to kimberlite magmas.

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  • Phase relationships and equations of state for FeS at high pressures and temperatures and implications for the internal structure of Mars Reviewed

    S Urakawa, K Someya, H Terasaki, T Katsura, S Yokoshi, KI Funakoshi, W Utsumi, Y Katayama, YI Sueda, T Irifune

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   143   469 - 479   2004.6

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    In situ X-ray diffraction experiments on Fes up to 22 GPa and 1600 K were carried out using large volume multianvil apparatus, combined with synchrotron radiation at SPring-8. We investigated phase stability relationships of Fes and determined the straight phase boundaries between Fes III (monoclinic phase) and Fes IV (hexagonal phase) to be T (K) = 20P (GPa) + 170 and between Fes IV and Fes V (NiAs-type phase) to be T (K) = 39.6 P (GPa) + 450. We also found anomalous behavior in the c/a ratio, thermal expansion, and isothermal compression of FeS V as well as FeS IV, in the pressure range 4-12 GPa. These anomalies in Fes can be attributed to the spin-pairing transition of Fe, and divides FeS IV and FeS V into the high-spin low-pressure phase (LPP) and the possibly low-spin high-pressure phase (HPP). In order to investigate the internal structure of Mars, we evaluated the equations of state for Fes IV (HPP) and Fes V (HPP). A least square fit to the experimental data yielded K(0T) = 62.5 +/- 0.9 GPa at T = 600 K and (dK(0)/dT) p = -0.0208 +/- 0.0028 GPa/K for Fes IV (HPP), and K(0T) = 54.3 +/- 1.0 GPa at T = 1000 K and (dK(0)/dT) = -0.0117 +/- 0.0015 GPa/K for Fes V (HPP) with fixed K&apos; = 4. Thermal expansion coefficients were alpha = 7.16 x 10(-5) + 6.08 x 10(-8) T for FeS IV (HPP) and alpha = 10.42 x 10(-5) for Fes V (HIPP), respectively. Using these equations of state, we examined the internal structure of Mars that has a model mantle composition [Meteoritics 20 (1985) 367] and Fe-FeS core. Our models show that an Mg-silicate perovskite-rich lower mantle is stable only with the Fe-rich core having less than 20 wt.% sulfur. The polar moment of inertia factor C derived from Mars Pathfinder data [Science 278 (1997) 1749] is consistent with any compositions between Fe and Fes for the Martian core, but it excludes the presence of a crust thicker than 100 km. (C) 2004 Elsevier B.V. All rights reserved.

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  • Viscosity of liquid sulfur under high pressure Reviewed

    H Terasaki, T Kato, K Funakoshi, A Suzuki, S Urakawa

    JOURNAL OF PHYSICS-CONDENSED MATTER   16 ( 10 )   1707 - 1714   2004.3

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    The viscosity of liquid sulfur up to 9.7 GPa and 1067 K was measured using the in situ x-ray radiography falling sphere method. The viscosity coefficients were found to range from 0.11 to 0.69 Pa s, and decreased continuously with increasing pressure under approximately constant homologous temperature conditions. The observed viscosity variation suggests that a gradual structural change occurs in liquid sulfur with pressure up to 10 GPa. The L-L' transition in liquid sulfur proposed by Brazhkin et al (1991 Phys. Lett. A 154 413) from thermobaric measurements has not been confirmed by the present viscometry.

    DOI: 10.1088/0953-8984/16/10/003

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  • New high-pressure viscosity determinations of NaAlSi3O8-H2O liquids

    Poe, B.T, Romano, C, Liebske, C, Terasaki, H, Rubie, D.C, Suzuki, A, Funakoshi, K

    Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik Universität Bayreuth Annual Report 2003   141 - 144   2004

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  • The viscosity of CaMgSi2O6 liquid at pressures up to 13 GPa Reviewed

    JE Reid, A Suzuki, KI Funakoshi, H Terasaki, BT Poe, DC Rubie, E Ohtani

    PHYSICS OF THE EARTH AND PLANETARY INTERIORS   139 ( 1-2 )   45 - 54   2003.9

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    The viscosity of CaMgSi2O6 (diopside) liquid has been determined up to 13 GPa and 2200degreesC using in situ falling sphere viscometry with X-ray radiography. The experiments were carried out in a 1500 1 multianvil apparatus at the SPring-8 synchrotron (Japan). A new, high-pressure sample assembly was developed with LaCrO3 replacing the traditionally used graphite furnace material, allowing experiments within the diamond stability field to be carried out. The viscosity of CaMgSi2O6 liquid increases slightly from 3.5 to 10 GPa and then decreases slightly at higher pressures. However, over the entire ranges of temperature (2030-2473 K) and pressure (3.5-13 GPa) investigated, variation in viscosity does not exceed +/-0.5 log units. The viscosity results from this study are consistent with those calculated from the pressure dependence of oxygen self-diffusion in CaMgSi2O6 liquid using the Eyring equation with a translation distance (lambda) of 0.45 nm providing the best correlation. Both sets of results indicate a change in pressure dependence at approximately 10 GPa, where viscosity results show a maximum with pressure and silicon and oxygen self-diffusivity results show a minimum. (C) 2003 Elsevier B.V. All rights reserved.

    DOI: 10.1016/S0031-9201(03)00143-2

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  • Determination of peridotite liquid transport properties at high pressure

    Schmickler, B, Rubie, D.C, Liebske, C, Suzuki, A, Terasaki, H, Poe, B.T

    Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik Universität Bayreuth Annual Report 2002   121 - 122   2003

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  • In situ viscosity measurements of albite melt under high pressure Reviewed

    K Funakoshi, A Suzuki, H Terasaki

    JOURNAL OF PHYSICS-CONDENSED MATTER   14 ( 44 )   11343 - 11347   2002.11

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    The viscosities of albite (NaAlSi3O8) melt under high pressures have been measured using an x-ray radiography falling sphere method with synchrotron radiation. This method has enabled us to determine the precise sinking velocity directly. Recent experiments of albite melt showed the presence of a viscosity minimum around 5 GPa (Poe et al 1997 Science 276 1245, Mori et al 2000 Earth Planet. Sci. Lett. 175 87). We present the results for albite melt up to 5.2 GPa at 1600 and 1700degreesC. The viscosity minimum is clearly observed to be around 4.5 GPa, and it might be explained not by the change of the compression mechanism in albite melt but by change of the phase itself.

    DOI: 10.1088/0953-8984/14/44/479

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  • Viscosity of albite melt at high pressure and high temperature Reviewed

    A Suzuki, E Ohtani, K Funakoshi, H Terasaki, T Kubo

    PHYSICS AND CHEMISTRY OF MINERALS   29 ( 3 )   159 - 165   2002.4

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    The viscosity of albite (NaAlSi(3)O(8)) melt was measured at high pressure by the in situ falling-sphere method using a high-resolution X-ray CCD camera and a large-volume multianvil apparatus installed at SPring-8. This system enabled Lis to conduct in situ viscosity measurements more accurately than that using the conventional technique at pressures of up to several gigapascals and viscosity in the order of 10(0) Pa s. The viscosity of albite melt is 5.8 Pa s at 2.6 GPa and 2.2 Pa s at 5.3 GPa and 1973 K. Experiments at 1873 and 1973 K show that the decrease in viscosity continues to 5.3 GPa. The activation energy for viscosity is estimated to be 316(8) kJ mol(-1) at 3.3 GPa. Molecular dynamics simulations suggest that a gradual decrease in viscosity of albite melt at high pressure may be explained by structural changes such as an increase in the coordination number of aluminum in the melt.

    DOI: 10.1007/s00269-001-0216-4

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  • Viscosity change and structural transition of Molten Fe at 5 GPa Reviewed

    H Terasaki, T Kato, S Urakawa, K Funakoshi, K Sato, A Suzuki, T Okada

    GEOPHYSICAL RESEARCH LETTERS   29 ( 8 )   10.1029/2001GL014321-   2002.4

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    [1] The in situ viscosity measurements of the pure molten Fe under high pressures were made by falling sphere X-ray radiography method. Viscosity coefficients at about 2000 K were 15-24 mPa s at 2.7-5.0 GPa, and 4-9 mPa s at 5.0-7.0 GPa. Drastic decrease was found at around 5 GPa, at which stable solid phase below the melting temperatures change from delta (bcc) to gamma (fcc) phases. The observation indicates the possibility that the structural change in the molten Fe occurs in a narrow pressure interval (1 GPa) at the similar condition with the phase transformation in the solid.

    DOI: 10.1029/2001GL014321

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  • Viscosity of komatiite magma at high pressure

    Suzuki, A, Ohtani, E, Urakawa, S, Terasaki, H, Kato, T

    Bayerisches Forschungsinstitut für Experimentelle Geochemie und Geophysik Universität Bayreuth Annual Report 2001   105 - 106   2002

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  • The effect of temperature, pressure, and sulfur content on viscosity of the Fe-FeS melt Reviewed

    H Terasaki, T Kato, S Urakawa, K Funakoshi, A Suzuki, T Okada, M Maeda, J Sato, T Kubo, S Kasai

    EARTH AND PLANETARY SCIENCE LETTERS   190 ( 1-2 )   93 - 101   2001.7

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    The Fe-FeS melt is thought to be the major candidate of the outer core material. Its viscosity is one of the most important physical properties to study the dynamics of the convection in the outer core. We performed the in situ viscosity measurement of the Fe-FeS melt under high pressure using X-ray radiography falling sphere method with a novel sample assembly. Viscosity was measured in the temperature, pressure, and compositional conditions of 1233-1923 K, 1.5-6.9 GPa, and Fe-Fe72S28 (wt%), respectively. The viscosity coefficients obtained by 17 measurements change systematically in the range of 0.008-0.036 Pa s. An activation energy of the viscous flow, Q = 30.0 +/- 8.6 kJ/mol, and the activation volume, DeltaV = 1.5 +/- 0.7 x 10(-6) m(3)/mol, are determined as the temperature and pressure dependence, and the viscosity of the Fe72S28 melt is found to be smaller than that of the Fe melt by 15 +/- 10%. These tendencies can be well correlated with the structural variation of the Fe-FeS melt. (C) 2001 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0012-821X(01)00374-0

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  • Radiographic study on the viscosity of the Fe-FeS melts at the pressure of 5 to 7 GPa Reviewed

    S Urakawa, H Terasaki, K Funakoshi, T Kato, A Suzuki

    AMERICAN MINERALOGIST   86 ( 4 )   578 - 582   2001.4

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    Stokes' viscometry combined with in situ X-ray radiographic observation, using the 6-8 type multi-anvil press and synchrotron radiation, has been applied to the viscosity measurement of the Fe-FeS melt up to pressures of 7 GPa. The viscosity is found to be about 2 x 10(-2) Pa-s at 5 to 7 GPa and temperatures about 1350 K, in marked contrast to previous viscosity measurements, which showed high viscosity, 0.5 to 14 Pa-s, at 2 to 5 GPa (LeBlanc and Secco 1996). Our viscosity data, however, is consistent with all other evidence, which include 1 atm viscosity data, X-ray structure analysis, and ab initio simulations. Recent viscosity measurements (Dobson et al. 2000) also showed the viscosity of Fe-FeS melt to be about 10(-2) Pa-s at 2.5 GPa. Thus, we are confident that the viscosity of the Fe-FeS melt is close to a typical value (10(-2) Pa-s) of viscosity for liquid metal even at high pressures.

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  • マルチアンビルを用いた高温高圧実験-手段と装置- Reviewed

    舟越賢一, 内海渉, 大高理, 入舩徹男, 井上徹, 伊藤英司, 桂智男, 久保敦, 廣瀬敬, 安藤淳一, 鈴木昭夫, 久保友明, 寺崎英紀

    岩石鉱物科学   30   100 - 101   2001

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    DOI: 10.2465/gkk.30.100

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  • In situ determination of the phase boundary between wadsleyite and ringwoodite in Mg2SiO4 Reviewed

    A Suzuki, E Ohtani, H Morishima, T Kubo, Y Kanbe, T Kondo, T Okada, H Terasaki, T Kato, T Kikegawa

    GEOPHYSICAL RESEARCH LETTERS   27 ( 6 )   803 - 806   2000.3

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    The phase boundary between wadsleyite and ringwoodite in Mg2SiO4 composition was determined by in situ observation using synchrotron X-ray and multi anvil apparatus:in KEK, Tsukuba, Japan. An energy dispersive method:was employed using the Ge solid state detector and the white X-ray beam from the synchrotron radiation source. The pressure was determined by the equation of state of NaCl. The stability field was identified by the change in intensities of diffraction lines of each phases. As a result, the phase boundary is expressed as a linear equation P=10.32(28)+0.00691(9)xT, where P is pressure in gigapascals and T is temperature in degrees Celsius.

    DOI: 10.1029/1999GL008425

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  • Pictorial 3 : Large Volume High Pressure and High Temperature Apparatus Used for Synchrotron X-ray In-situ Observation

    KATO Takumi, TERASAKI Hidenori, KUBO Tomoaki

    J. Geogr.   109 ( 6 )   Plate5 - Plate5   2000

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    DOI: 10.5026/jgeography.109.6_Plate5

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  • Viscosity of melt in diopside-jadeite system at high pressure by X-ray radiograph

    Suzuki, A, Ohtani, E, Maeda, M, Sato, J, Terasaki, H, Funakoshi, K

    SPring-8 User Experiment Report No.4 (1999B)   46   2000

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  • In situ X-ray observation of the phase boundary of β- and γ-Mg2SiO4

    Suzuki, A, Kubo, T, Ohtani, E, Kanbe, Y, Okada, T, Terasaki, H, Kato, T, Kikegawa, T

    Photon Factory Activity Report   16   222   1999

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  • Precise determination of pyroxene-garnet phase equilibrium relations using in situ X-ray observation

    Okada, T, Kato, T, Terasaki, H, Kubo, T, Suzuki, A, Ohtani, E, Kikegawa, T

    Photon Factory Activity Report   16   216   1999

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  • Viscosity of basaltic silicate melt at high pressure

    Funakoshi, K, Suzuki, A, Terasaki, H, Kanzaki, M

    SPring-8 User Experiment Report No. 3 (1999A)   67   1999

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▼display all

Books

  • 高圧力の科学・技術事典

    入舩 徹男, 舟越 賢一, 近藤 忠, 関根 利守, 清水 克哉, 長谷川 正, 保科 貴亮, 木村 佳文, 加藤 稔, 松木 均( Role: Contributor ,  94-95;172-173)

    朝倉書店  2022.11  ( ISBN:9784254102970

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    Total pages:17,458p   Language:Japanese Book type:Dictionary, encyclopedia

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  • 基礎地学実験

    廣野哲郎, 佐伯和人, 寺崎英紀, 境家達弘, 横田勝一郎, 松尾太郎, 芝井広( Role: Contributor ,  11-18)

    学術図書出版社  2020.3  ( ISBN:9784780608236

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    Total pages:i, 42p   Language:Japanese Book type:Textbook, survey, introduction

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  • Magmas Under Pressure: Advances in High-Pressure Experiments on Structure and Properties of Melts

    Terasaki, H, K. Nishida( Role: Contributor ,  pp237–260)

    Elsevier  2018.6 

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  • Deep Earth: Physics and Chemistry of the Lower Mantle and Core

    H. Terasaki, R.A. Fischer( Role: Edit)

    AGU/Wiley  2016.4 

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MISC

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Presentations

  • Wetting property of Fe–S melt in solid core: Implication to core crystallization process in planetesimals

    S. Matsubara, H. Terasaki, T. Yoshino, S. Urakawa, D. Yumitori

    Workshop on Interiors of planetesimals and terrestrial planets 

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    Event date: 2023.11.28

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  • Possibility of percolative core formation in planetesimals

    H. Terasaki, T. Yoshino, G. D. Bromiley, I. Butler, K. Kobayashi, S. Matsubara, T. Miura

    Workshop on Interiors of planetesimals and terrestrial planets 

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    Event date: 2023.11.28

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  • レーザー加熱式ダイヤモンドアンビルセルを用いたX線吸収法によるFeSの密度測定

    森岡康, 寺崎英紀, 紙名宏幸, 鶴岡椋, 近藤忠, 米田明, 櫻井萌, 河口沙織

    日本鉱物科学会2023年年会 

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    Event date: 2023.9.14 - 2023.9.16

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  • レーザー加熱式DACとX線吸収法を組み合わせた高温高圧下でのニッケル密度測定

    寺崎英紀, 紙名宏幸, 鶴岡椋, 近藤忠, 米田明, 森岡康, 櫻井萌, 鎌田誠司, 河口沙織

    日本鉱物科学会2023年年会 

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    Event date: 2023.9.14 - 2023.9.16

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  • History of technological development of the GHz-DAC ultrasonics

    A. Yoneda, R. Tsuruoka, T. Kato, S. Kamada, H. Terasaki, T. Kondo, D. Yamazaki

    Japan Geoscience Union meeting 2023 

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    Event date: 2023.5.21 - 2023.5.26

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  • 3D distribution of FeS melt in orthopyroxene mantle: Implication to core segregation in planetesimals

    H. Terasaki, T. Yoshino, G. D. Bromiley, I. B. Butler, T. Miura, S. Matsubara, K. Kobayashi

    Japan Geoscience Union meeting 2023 

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    Event date: 2023.5.21 - 2023.5.26

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  • Evaluation of Fe–S melt segregation in solid core during core crystallization in planetesimals

    S. Matsubara, H. Terasaki, T. Yoshino, S. Urakawa, K. Kobayashi, G. D. Bromiley, I. Butler

    Japan Geoscience Union meeting 2023 

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    Event date: 2023.5.21 - 2023.5.26

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  • The effect of porosity on FeS melt migration in orthopyroxene mantles in planetesimals

    K. Kobayashi, H. Terasaki, T. Yoshino, S. Matsubara, S. Urakawa, G. D. Bromiley, I. B. Butler

    Japan Geoscience Union meeting 2023 

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    Event date: 2023.5.21 - 2023.5.26

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  • Fe-FeS系合金における固液共存組織の時間と圧力変化 Invited

    寺崎英紀

    新結晶成長学シンポジウム 

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    Event date: 2023.3.28 - 2023.3.29

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

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  • 快削性ボロン添加ダイヤモンドヒーターを用いた高温高圧発生

    辻野典秀, 寺崎英紀, 櫻井萌

    第63回高圧討論会 

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    Event date: 2022.12.13 - 2022.12.15

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  • Conditions of core melt segregation in planetesimals Invited

    H. Terasaki, T. Miura, T. Yoshino, T. Kondo

    Goldschmidt Conference 

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    Event date: 2022.7.10 - 2022.7.15

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  • Pressure change of melting relations of the system Fe—FeS—FeO.

    K. Tsuji, S. Matsubara, H. Terasaki, S. Urakawa

    Japan Geoscience Union meeting 2022 

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    Event date: 2022.5.22 - 2022.5.27

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  • Wetting ability of liquid Fe–S in solid core during planetesimal core crystallization

    S. Matsubara, H. Terasaki, T. Yoshino, D. Yumitori, S. Urakawa

    Japan Geoscience Union meeting 2022 

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    Event date: 2022.5.22 - 2022.5.27

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  • Experimental study on the timescale of core segregation in planetesimals

    H. Terasaki, T. Miura, T. Kondo, T. Yoshino

    Japan Geoscience Union meeting 2022 

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    Event date: 2022.5.22 - 2022.5.27

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  • Constraint on the condition of core melt segregation in pyroxene mantle of planetary embryo

    T. Miura, H. Terasaki, T. Yoshino, S. Matsubara, O. Ohtaka, T. Kondo

    Japan Geoscience Union meeting 2022 

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    Event date: 2022.5.22 - 2022.5.27

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  • Test of density measurement using X-ray absorption method combined laser-heated diamond anvil cell

    R. Tsuruoka, H. Terasaki, H. Kamina, S. Kamada, T. Kondo, A. Yoneda, N. Hirao, S. Kawaguchi

    Japan Geoscience Union meeting 2022 

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    Event date: 2022.5.22 - 2022.5.27

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  • Development of GHz Ultrasonic Velocity Measurement in Diamond Anvil Cell: Ⅳ

    Japan Geoscience Union meeting 2022 

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    Event date: 2022.5.22 - 2022.5.27

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  • レーザー加熱式DACを用いたX線吸収法による密度測定の試み

    寺崎英紀, 鎌田誠司, 紙名宏幸, 鶴岡椋, 近藤忠, 米田明, 河口沙織, 平尾直久

    高圧討論会 

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    Event date: 2021.10.18 - 2021.10.20

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  • GHz 音速法における技術開発続報:ダイヤモンドアンビル変形解析と測定系のインピーダンス整合

    米田 明, 鶴岡 椋, 加藤拓人, 鎌田誠司, 寺崎 英紀, 近藤 忠, 山崎 大輔

    高圧討論会 

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    Event date: 2021.10.18 - 2021.10.20

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  • GHz-DAC法による高圧下での鉄の音速測定

    鶴岡椋, 米田明, 加藤拓斗, 鎌田誠司, 寺崎英紀, 近藤忠, 山崎大輔, 平尾直久, 河口沙織

    高圧討論会 

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    Event date: 2021.10.18 - 2021.10.20

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  • Wetting property of Fe-S melt in solid iron: Implication to core crystallization in planetesimals

    D. Yumitori, H. Terasaki, T. Yoshino

    Japan Geoscience Union meeting 2021 

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    Event date: 2021.6.3 - 2021.6.6

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  • Structural study on the Ca2MgAl2Si4O14 composition melt under pressure

    N. Adachi, S. Urakawa, H. Terasaki

    Japan Geoscience Union meeting 2021 

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    Event date: 2021.6.3 - 2021.6.6

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  • GHz ultrasonic velocity measurements of iron beyond the bcc-hcp transition II: sample thickness determination using X-ray imaging method

    R. Tsuruoka, A. Yoneda, S. Kamada, H. Terasaki, T. Kondo, D. Yamazaki

    Japan Geoscience Union meeting 2021 

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    Event date: 2021.6.3 - 2021.6.6

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  • Possibility of percolation of Fe-S melts in asteroids

    T. Miura, H. Terasaki, T. Kondo, O. Ohtaka, T. Yoshino

    Japan Geoscience Union meeting 2021 

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    Event date: 2021.6.3 - 2021.6.6

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  • Deuterium content and site occupancy in iron sulphide at high pressure and high temperature: Implications for the oxidation of early Earth’s mantle

    Sumith Abeykoon, Christopher. M. Howard, Serena Dominijanni, Lisa Eberhard, Daniel J. Frost, Tiziana Boffa Ballaran, Alexander Kurnosov, Hidenori Terasaki, Tatsuya Sakamaki, Akio Suzuki, Eiji Ohtani, Asami Sano-Furukawa, Jun Abe

    Goldschmidt conference 

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    Event date: 2021

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  • レーザー衝撃圧縮を受けたシリカの高圧変成分布

    近藤忠, 大野正和, 境家達弘, 廣本健吾, 寺崎英紀, 重森啓介, 弘中陽一朗

    高圧討論会 

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    Event date: 2020.12.2 - 2020.12.4

    Language:Japanese   Presentation type:Poster presentation  

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  • 鉄の高圧弾性:GHz-DAC 法によるP 波S 波速度測定

    米田明, 鶴岡椋, 鎌田誠司, 近藤忠, 寺崎英紀, 山崎大輔

    高圧討論会 

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    Event date: 2020.12.2 - 2020.12.4

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  • Mercury core size constrained from elastic properties of Fe-Ni-S-Si liquid

    I. Yamada, H. Terasaki, R. Tsuruoka, A. Kamiya, T. Miura, T. Kondo, Y. Tange, Y. Higo

    Japan Geoscience Union meeting 2020  2020.6.12 

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    Event date: 2020.6.12 - 2020.6.16

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  • Possibility of percolation of Fe-S melts in asteroids

    T. Miura, H. Terasaki, T. Kondo

    Japan Geoscience Union meeting 2020  2020.6.12 

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    Event date: 2020.6.12 - 2020.6.16

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  • Thermodynamic analysis of density of Fe-Ni-S melts at high pressure

    S. Urakawa, H. Terasaki, A. Machida

    Japan Geoscience Union meeting 2020  2020.6.12 

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    Event date: 2020.6.12 - 2020.6.16

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  • Density measurements of Fe up to 25 GPa based on X-ray absorption

    S. Kamada, F. Maeda, H. Terasaki, R. Tsuruoka, Y. Takubo, S. I. Kawaguchi, N. Hirao, A. Machida

    Japan Geoscience Union meeting 2020  2020.6 

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    Event date: 2020.6.12 - 2020.6.16

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • Density a;elastic properties of liquid;gallium using externally heated diamo;anvil cell

    R. Tsuruoka, H. Terasaki, S. Kamada, F. Maeda, T. Kondo, I. Yamada, S. Urakawa, A. Yoneda, N. Hirao, S. I. Kawaguchi, N. Hirao, A. Machida

    Japan Geoscience Union meeting 2020  2020.6 

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    Event date: 2020.6.12 - 2020.6.16

    Language:Japanese   Presentation type:Oral presentation (general)  

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Awards

  • Fellow

    2023.10   Mineralogical Society of America  

    Hidenori Terasaki

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  • 総長顕彰(研究部門)

    2015.7   大阪大学  

    寺崎 英紀

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  • Excellence in Peer Review

    2014.6   Physics and Earth Planetary Interiors, Elsevier  

    Hidenori Terasaki

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  • young scientist award

    2008.11   The Japan Society of High Pressure Science and Technology  

    Hidenori Terasaki

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  • young scientist award

    2008.9   Japan Association of Mineralogical Sciences  

    Hidenori Terasaki

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Research Projects

  • Elasticity associated with the iron spin transition by means of GHz ultrasonics

    Grant number:21H01179  2021.04 - 2025.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    米田 明, 近藤 忠, 寺崎 英紀, 山崎 大輔

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    Grant amount:\17160000 ( Direct expense: \13200000 、 Indirect expense:\3960000 )

    本研究経費を得て、以下に示す投資を行うことができた。
    ①本年度に岡山大学からGHz測定装置を大阪大学に移設し、大阪大学で大学院生と共同して研究を進める体制を整えた。②金属製の中型キャビネットを購入しGHz音速測定部を内部に置くことで外来ノイズの遮蔽を行った。この結果、従前に見られたスパイク状のノイズがほとんど観測されなくなった。③低ノイズのプレアンプを導入し、さらに、④高速電子スイッチをファンクション発振器で制御するシステムを構築し、シグナルのSN比の向上を実現した。
    この他にも、⑤ZnO圧電素子に対するインジウム電極の形状の改善と圧着状態の解明、⑥バッファロッド用基板結晶と白金電極の間に接着性改善のためのクロムのプレスパッタリング導入、など研究を安定的に進展させるための技術開発を行った。
    このような技術開発をもとにMgOの測定を行った。MgOは先行研究が多く、GHz測定の信頼性確認に最適の物質である。同一セルで初めてP波とS波の測定に成功した。圧力はSPring-8でのX線格子定数の測定から0.6GPaと決定された。試料の厚さは、回収後のガスケットの厚さから見積もった。最終的に得られたP波速度とS波速度比は1.63と先行研究と調和的結果が得られた。
    これらの成果を踏まえて、フェロペリクレースを合成しスピン転移での音速測定実施の機運が熟したといえる。そのために向けて大阪大学大学院生と協力し本研究課題達成のために邁進する。一方、前年度から継続中の鉄の音速測定も上記技術開発の結果を経て進展中である。これらの結果を含めてこれまで独自開発を行ってきたGHzーDAC音速法の技術論文を早期投稿する。

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  • Study of Martian core structure based on density and sound velocity measurements

    Grant number:20H02008  2020.04 - 2024.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    寺崎 英紀, 米田 明, 鎌田 誠司

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    Grant amount:\18070000 ( Direct expense: \13900000 、 Indirect expense:\4170000 )

    本課題では、ダイヤモンドアンビルセル(DAC)を用いた密度と弾性波速度の複合測定により、Fe-Ni合金融体の密度と弾性特性を決定し、火星コア条件でのコア物質の圧縮曲線、状態方程式の決定を目指している。最近、InSight探査機による火星地震データから火星の内部構造が報告された。この最新の内部構造モデルから火星コア組成を制約するには、コア条件でのFe-S融体の状態方程式決定が不可欠となる。
    本研究では、密度測定に試料のX線透過率から密度を導出するX線吸収法を用い、弾性波速度測定にGHz超音波パルス干渉法を用いている。
    2021年度の密度測定では、両面レーザー斜入射加熱による高温高圧下の測定を本格的に実施した。Ni試料では、24 GPaまでの1600-1750 Kでの圧縮曲線を得ることができた。同時にX線回折からNiの密度を決定し、吸収法による密度と比較し整合的な結果が得られた(高圧討論会で発表)。次にFe-SとFe3C試料について測定をおこなった。液体での測定を目指すため、鉄合金試料はアルミナ単結晶圧媒体を用いて、10 GPa, 1750 KまでのX線透過率測定を行った。またX線吸収法と外熱式DACを用いた10 GPaまでの液体Gaの密度結果をHigh Pressure Research誌に発表した(Tsuruoka, Terasaki et al. 2021)。
    2021年度の弾性波速度測定では、共同研究者の米田博士によりDACを用いGHz超音波法の技術開発およびFe試料の測定を実施した。技術開発としては、低ノイズプレアンプと高速スイッチを用いることで、シグナルのSN比を向上させることができた。Fe試料の弾性波速度測定は、X線吸収測定で試料厚みを求め、6 GPaまでの圧力条件で弾性波速度を決定した。また抵抗ヒーターを用いた外熱法を採用し、高温高圧下での弾性波速度測定を開始した。

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  • Density measurements and structure of Fe and Fe-light elements alloy liquid

    Grant number:16K13902  2016.04 - 2019.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    Kamada Seiji, TERASAKI Hidenori

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    Grant amount:\3640000 ( Direct expense: \2800000 、 Indirect expense:\840000 )

    The Earth core is divided into liquid and solid cores. Densities of the cores were estimated seismologically and they are smaller than those of pure Fe, suggesting light elements exist in the cores. Therefore, it is very important to investigate densities of core materials. However, it is difficult to measure densities of liquid phases. In this study, I have measured densities of crystalline Fe under high pressures based on an X-ray absorption method in order to establish the method. The densities of Fe were obtained based on the X-ray absorption method and XRD. The densities of Fe based on the X-ray absorption method were consistent with those based on XRD. The difference were less than 2%. This suggests that the X-ray absorption method is a strong method to measure densities, especially liquid and amorphous.

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  • Structure and properties of the core-mantle materials

    Grant number:15H05828  2015.06 - 2020.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    Suzuki Akio

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    Grant amount:\186550000 ( Direct expense: \143500000 、 Indirect expense:\43050000 )

    We investigated the structure and properties of deep-Earth materials. We developed experimental techniques in collaboration with the A01-3 Group, using high pressure-temperature ultrasonic methods to measure the elastic wave velocities of hydrous and non-hydrous phases in the Earth's mantle. Moreover, we measured the velocities of silicate glasses, magmas, and metallic liquids under high pressure and temperature to study the heterogeneous structure of the Earth's deep interior. We conducted melting experiments on mantle materials under high pressure, and developed a model that attribute the chemical heterogeneity of the mantle to the transportation of ultrabasic magmas. Through the investigation of the solubility of nitrogen in silicate minerals at high pressure, we revealed that stishovite contains higher amounts of nitrogen compared to other minerals. Based on these experimental results, we proposed a new model for stishovite-transported nitrogen in the Earth's mantle and core.

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  • Composition and dynamics of Mercury and Mars cores approached from physical properties under high pressures

    Grant number:26247089  2014.04 - 2018.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (A)

    Terasaki Hidenori, NISHIDA Keisuke, KONDO Tadashi, SUZUKI Akio, SASAKI Sho

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    Grant amount:\39520000 ( Direct expense: \30400000 、 Indirect expense:\9120000 )

    To clarify the core compositions of Mercury and Mars, elastic properties of liquid and solid Fe-alloys were investigated up to the planetary core conditions. We developed simultaneous sound velocity and density measurement system under high pressure and obtained relationship between sound velocity and density. It is found that the effect of alloying elements (C, S, Si, Ni) on the elastic properties of iron shows significantly different trend depending on alloying elements. Based on these results, we estimated the composition and conditions of the planetary cores.

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  • Experimental study of gravitational instability using high power laser: Implication to early Earth differentiation

    Grant number:26610141  2014.04 - 2016.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    Terasaki Hidenori, SAKAIYA Tatsuhiro

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    Grant amount:\3640000 ( Direct expense: \2800000 、 Indirect expense:\840000 )

    In order to clarify the core/mantle differentiation process controlled by gravitational instability, we have carried out in situ observation of gravitational instability of Fe-alloy under high pressure and temperature. By adding gravity to the sample using high power laser (GEKKO-XII), a surface perturbation of the sample was measured based on X-ray absorption imaging. It is found that an amplitude of the perturbation increased with time and that growth rate of the perturbation changed depending on the sample composition and existence of silicate layer on the sample. In this study, we successfully measured the perturbation growth of Fe-alloy samples caused by gravitational instability. The obtained results give us important information regarding terrestrial core formation mechanism and its time scale.

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  • The effect of light elements on density and elastic wave velocity of liquid Fe: Implication to light elements in the Earth's outer core

    Grant number:23340159  2011.04 - 2015.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    TERASAKI Hidenori, URAKAWA Satoru, UESUGI Kentaro, FUNAKOSHI Ken-ichi

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    Grant amount:\17680000 ( Direct expense: \13600000 、 Indirect expense:\4080000 )

    In order to clarify the effects of light elements on density and elastic wave velocity of liquid Fe-alloy and to constrain the terrestrial core compositions, we have developed simultaneous measurement system of density and sound velocity for liquid materials under pressure. Density and elastic wave velocity were obtained simultaneously for liquid Ni-S and it is found that there is a linear relationship between these two physical properties. We also obtained following results; density and sound velocity of liquid Fe-Ni-C, effect of pressure on density of Fe-C and on sound velocity of Fe-Ni-C. These results provide important aspects for understanding the effect of light elements on the elastic properties of liquid Fe.

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  • Permeable flow of liquid Fe alloy through silicate grain boundary

    Grant number:23340129  2011.04 - 2015.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    URAKAWA Satoru, TERASAKI Hidenori, FUNAKOSHI Ken-ichi, UESUGI Kentaro, HASHIMOTO George

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    Grant amount:\20800000 ( Direct expense: \16000000 、 Indirect expense:\4800000 )

    At the early history of the solar system, molten iron alloy is separated from silicate mantle to form an iron core at the center of the protoplanets. We investigated this process by using high-pressure and high-temperature experiments combined with synchrotron X-ray micro computed tomography. We found that a permeable flow of liquid iron alloy through the crystalline silicate grain boundary is a dominant core-mantle separation process in the protpplanets with which the radius is smaller than several hundred km.

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  • Development of neutron tomography under pressure: 3D distribution of fluid in the mantle minerals

    Grant number:23654181  2011 - 2013

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Challenging Exploratory Research

    TERASAKI Hidenori, INOUE Toru

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    Grant amount:\2860000 ( Direct expense: \2200000 、 Indirect expense:\660000 )

    In this study, we have developed neutron computed-tomography(CT) technique under high pressure in order to reveal in situ 3D distribution of H2O fluid in the mantle minerals. Newly designed heating and compress systems for CT measurement have been installed to the portable PE press. Optical set-up for neutron imaging was optimized at J-PARC neutron facility and the effects of sample material and its size on the image contrast were investigated. Neutron tomography measurement for hydrous and anhydrous mineral samples was carried out using new system. The present new system able us to perform neutron imaging and tomography measurements under high pressure and temperature

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  • Ultrahigh-Pressure Material Science of the central regions of the Earth and Planets

    Grant number:22000002  2010.04 - 2015.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Specially Promoted Research

    OHTANI Eiji, MURAKAMI Motohiko, SUZUKI Akio, TERASAKI Hidenori, HIRAO Naohisa, MIYAHARA Masaaki, FUKUI Hiroshi, SAKAI Takeshi, SAKAMAKI Tatsuya, KAMADA Seiji

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    Grant amount:\482430000 ( Direct expense: \371100000 、 Indirect expense:\111330000 )

    We determined the melting relations of Fe-S, Fe-C, Fe-H, Fe-Ni and Fe-S-Si, Fe-S-H systems, and compression of hcp-FeNiSi and hcp-FeNiS alloys, Fe_3S, and Fe3C to the core conditions. We also successfully measured compressional velocity of hcp-iron to 173 GPa at 3000 K, which are the data determined at the highest pressure and temperature by the IXS method. We also determined the spin-state and magnetic properties of the iron-oxides and iron-light element compounds at high pressure. Based on these experimental results we proposed the model of the composition and the temperature profile of the core.

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  • Physical property and structure of magma under high pressure, and the effect of water

    Grant number:20103003  2008 - 2012

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    INOUE Toru, URAKAWA Satoru, URAKAWA Satoru, SUZUKI Akio, MIBE Kenji, KAWAMOTO Tatsuhiko, ARIMA Hiroshi, KAWAMOTO Tatsuhiko, FUNAKOSHI Ken-ichi, FUNAMORI Nobumasa, TERASAKI Hidenori, NAKAMURA Michihiko, YAMADA Akihiro

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    Grant amount:\97890000 ( Direct expense: \75300000 、 Indirect expense:\22590000 )

    We have developed the cell assembly for high temperature high-pressure neutron experiment and also installed a neutron camera with various examinations together with construction of the high temperature high-pressure neutron beamline in J-PARC. In addition, we have performed experimental studies about the effect of water and the structure and the physical properties of magma generated in the Earth interior by in-situ synchrotron X-ray observation and quench experiment under high temperature and high pressure. The high temperature and high-pressure neutron experiment was enabled by this project research, and new knowledge, such as structure of magma, density, and viscosity, was acquired.

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  • X線トモグラフィー用高温高圧装置の開発

    Grant number:19654082  2007 - 2008

    日本学術振興会  科学研究費助成事業  萌芽研究

    浦川 啓, 舟越 賢一, 寺崎 英紀, 上杉 健太朗

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    Grant amount:\3400000 ( Direct expense: \3400000 )

    X線マイクロトモグラフィを使った高温高圧下における3次元イメージングからは試料の形状,体積,界面などの情報が非破壊で得られるため,高圧力科学の分野の応用性を広める技術である。我々はその地球科学的な応用研究をアメリカ合衆国の放射光施設Advanced Photon Source(APS)で行った(平成18〜19年度)。本研究では,そのときの経験をもとにX線マイクロトモグラフィ用に新しい高圧装置を開発した。平成19年度に作製した高圧装置はSPring-8のイメージング用ビームラインで使用することを念頭に設計され,総重量30kg最大荷重80トンの小型のものである。平成20年度はこの小型高圧装置の性能評価を兼ねてX線マイクロトモグラフィ実験をSPring-8のBL20B2で行った。再構築したCTイメージには高圧装置のフレームに起因する影が認められるが,形状は柱のない場合と解像度の範囲内では一致した。圧力4GPa温度1000Kまでの実験でも十分に可視領域が確保され内部のCT像を得ることが可能であった。このように所定の性能を発揮することを確認した。APSにおけるX線マイクとトモグラフィと比較すると,高圧装置の加圧能力は約2倍,データ収集時間は1/10以下,解像度は2倍程度,我々の方が優れていた。SPring-8とAPSではビームラインのスペックの差もあるが非常に満足の出来る結果であった。高圧装置は高輝度光科学研究センターに寄付されており,共同利用が可能である。

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  • Structure and Evolution of the Earth's Core

    Grant number:18104009  2006 - 2009

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

    OHTANI Eiji, SUZUKI Akio, TERASAKI Hidenori, KONDO Tadashi, KIKEGAWA Takumi, MIYAHARA Masaaki

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    Grant amount:\105040000 ( Direct expense: \80800000 、 Indirect expense:\24240000 )

    We have clarified the phase and melting relations of the iron-light element systems to the earth's core conditions, the reactions of metallic iron and silicates at the core-mantle boundary, and the physical properties of metallic melts at high pressure. Using these data, we discussed the mechanism of the core formation and the nature and properties of the Earth's core.

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  • 月及び火星からの隕石飛来機構の解明

    Grant number:18654091  2006 - 2007

    日本学術振興会  科学研究費助成事業  萌芽研究

    大谷 栄治, 木村 眞, 寺崎 英紀, 高山 和喜

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    Grant amount:\3200000 ( Direct expense: \3200000 )

    本研究では,火星阻石や月起源の隕石の構成鉱物の同定を行い,そこに含まれる鉱物に認められる衝撃組織,焼結組織を記載し,コンドライト隕石の衝撃溶融脈に認められる衝撃組織との違いを明らかにすることを目的にしている.
    本年度は,本研究を実施するために,備品としてカーボンコーターを導入した.これによって,走査電子顕微鏡,EPMAの試料の蒸着が迅速簡便に行うことが可能になった.火星隕石(シャゴッタイト)の衝撃波組織の顕微鏡観察,走査電子顕微鏡観察,ラマン分光測定を開始した.さらに透過電子顕微鏡観察用にFIB(収束イオンビームシステム)を用いた隕石試料の加工法の確立を目指した.月火星隕石の衝撃波組織との比較を行うために比較的容易に手に入れることができるコンドライト隕石の衝撃波溶融脈中の衝撃波組織の詳細な記載方法の検討を行った.また,この衝撃波組織について,透過電子顕微鏡観察により,衝撃波による相転移相の組織観察と分析電子顕微鏡による組成分析を試みた.また,コンドライト隕石中のリン酸塩鉱物を用いて,衝撃年代が得られるか否かの予備的測定を広島大学の寺田博士の協力のもとで行なった.以上の実験によって,月・火星隕石の透過顕微鏡観察と微細スケールでの解析分析の方法がほぼ確立できた.

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  • 火星中心核までの高圧力条件における鉄合金メルトの粘性測定

    Grant number:17740343  2005 - 2006

    日本学術振興会  科学研究費助成事業  若手研究(B)

    寺崎 英紀

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    Grant amount:\3700000 ( Direct expense: \3700000 )

    惑星中心核の物性や初期惑星内部における核形成過程を理解するためには、広範な温度圧力領域における核構成物質の粘性測定を行うことが重要である。本研究では、中心核を構成するとされる鉄-軽元素系合金のうち、有力な軽元素と考えられる硫黄、炭素に注目し、Fe-S, Fe-C融体の粘性を、世界最高の測定条件である16 GPa,1843Kまでの温度・圧力条件で測定することに成功した。実験は、大型放射光雄設SPring-8ビームライン04B1のマルチアンビル高圧装置を用い、試料中のマーカー球の落下速度、をCCDカメラによりその場観察するX線影像落球法を用いて粘性測定を行った。高圧発生用に開発した超硬アンビルの朱端サイズ5mmのセルを用いた。ヒーター材質乏しては、肉厚を薄く加工したランタンクロマイドを使用した。また粘性マーカーのRe球と鉄合金試料との化学反応を防ぐために、RFスパッタ装置を用いて、Re球を厚さ1-2ミク-ロンのアルミナでコーティングした。このように碓立された高圧セルを用いて、取り込み速度が最高125プレーム/秒の高速度カメラと組み合わせることにより、Fe-S, Fe-Cメルトの粘性を測定し、その圧力依存性を精度良く求めることができた。
    Fe-S共融組成メルトは、16 GPa,1798Kまでの温度・圧力条件において、粘性係数は3.2-8.6 Pa-sとなり、その圧力依存性すなわち粘性流動の活性化体積は、1.46cm^3/molと非常に小さいことが明らかとなった。一方、Fe-Cメルトについては、4.5GPa,1843Kまでの条件において、粘性係数は1.7・7-6 Pa-sとなり、その活性化体積は1.20cm^3/molということがわかった。これにより、Fe-S, Fe-Cメルトの粘性の圧力依存性は、いずれも小さく、大差ないことが明らかとなり、惑星内部においても核メルトの粘性は非常に小さいと推測される。

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  • X線影像を用いた高圧下におけるマグマの密度測定法の開発

    Grant number:17654102  2005 - 2006

    日本学術振興会  科学研究費助成事業  萌芽研究

    鈴木 昭夫, 大谷 栄治, 近藤 忠, 寺崎 英紀

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    Grant amount:\3100000 ( Direct expense: \3100000 )

    惑星の内部構造やダイナミクスを理解する上で鉄合金融体の密度は基本的な物性値である。しかしながら、現在まで高圧下での鉄合金融体の密度測定は数例しか行われていない。浮沈法を用いたFe-S融体の密度測定Balog et al.(2003)やNishida et al.(submitted)で行われている。X線吸収法によるFe-S(S=10,20,and 27wt%)融体の密度測定は圧力が1.5-6.2GPa、温度が1500-1780K範囲で(Sanloup et al. 2000)によって行われている。本研究では,X線吸収コントラストイメージを用いて密度測定を行った。この方法は透過X線強度がX線吸収コントラストイメージの明るさに比例する原理に基づいており、1度の露光で試料を通過した2次元の透過X線強度の情報を得ることができるのが利点である。
    本研究ではFeS融体の密度をKEK-PFのBL14C2において5GPa、1900Kまでの条件で密度測定を行った。1.3GPa、1600KにおけるFeS融体の密度は4.23g/cm^3であった。本研究で得られた1.3GPa-1600KのFeS融体の密度と4.2GPa-1573Kの密度(Chen et al. 2005)と1atm-1600Kの密度(Kaiura et al.,1979)を用いて得られた等温体積弾性率(K_T)はK'が4から6の範囲でおのおの12.3から14.6GPaであった。
    本研究によって、X線イメージを用いる密度測定法が、従来のX線吸収法の限界であった圧力を大幅に拡大できるものであることが明らかとなった。

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  • Modeling of slab stagnation and falling processes

    Grant number:16075202  2004 - 2008

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research on Priority Areas

    OHTANI Eiji, SUZUKI Akio, TERESAKI Hidenori, NAGASE Toshio, HIROSE Kei, MURAKAMI Motohiko, SAKAI Takeshi, KONDO Tadashi, KUBO Tomoaki, KOMIYA Tsuyoshi, OOISHI Yasuo

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    Grant amount:\258200000 ( Direct expense: \258200000 )

    水の存在下でマントル遷移層の相転移境界の深さが変化する。揮発性物質を含むマグマの密度測定によると、このマグマが上部マントル最下部で安定である。これらの結果から滞留した深部スラブからの脱水と上部マントル下部での重い含水マグマの生成というDeep Dehydration modelを提案した。パイロライトやMORB組成中のポストペロフスカイト相転移境界を決定し、D"不連続面の成因をあきらかにした。下部マントル全域でMORB成分はカンラン岩成分より重く、核マントル境界にMORB成分が堆積する。

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  • Experimental study on the melting relation of silicate under the lowermost mantle condition

    Grant number:16340164  2004 - 2006

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

    KONDO Tadashi, OHTANI Eiji, SUZUKI Akio, TERASAKI Hidenori

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    Grant amount:\16500000 ( Direct expense: \16500000 )

    In this research project, we investigated the phase relation of the minerals under the lowermost mantle condition and the chemical reaction between those minerals and molten iron up to the condition corresponding to the earth's core-mantle boundary. For realizing such extreme conditions, we newly designed a symmetrical diamond anvil cell with a wide conical window for laser-heating and optical spectroscopy. The laser-heating system was also refined for stable heating and optimal temperature measurement from the hot sample by a spectroradiometric method. Experiments were performed using these techniques at SPring-8 and Photon Factory for in-situ X-ray diffraction measurements at high P-T, and also at laboratory for recovery runs to check the quenched samples. Thanks for the recent advances in micro-processing technologies such as laser cutting, focused ion beam, we successfully prepared the thin section of the recovered samples for analytical transmission electron microscopy. Finally we obtained the following results. (1) The chemical reaction between molten iron and perovskite and post-perovskite phase and wetting property at the core-mantle boundary condition was examined, and silicon and oxygen turned to be important candidates as light elements in the outer core. The wetting angle between post-perovskite phase and molten iron was slightly higher than the critical angle of 60°, which means 2wt% of the core material can be trapped in the D" layer. (2) Magnesiowustite is the heaviest minerals overall the mantle based on the iron partitioning experiments between magnesium oxide and silicate perovskite and post-perovskite phase. No evidence for the effect of a high-spin to low-spin transition was found in these minerals. (3) Potassium can be dissolved into molten iron significantly at core-mantle boundary condition, and the element may work as a heat source in the core. (4) The hydrous mineral, delta-AIOOH, has a wide stability field over 100GPa and 2000K, therefore this phase at relatively low temperature condition in descending slab possibly survive to the lowermost mantle to supply the water to core-mantle boundary. (5) Potassium bearing silicate with post-hollandite structure can be stably exist at the lowermost mantle condition.

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  • 巨大惑星の内部構造に関する実験的研究

    Grant number:16654083  2004 - 2005

    日本学術振興会  科学研究費助成事業  萌芽研究

    近藤 忠, 大谷 栄治, 鈴木 昭夫, 寺崎 英紀

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    Grant amount:\3500000 ( Direct expense: \3500000 )

    本年度は、木星・土星の主成分と考えられる水素-ヘリウム系の混合ガスを使った高圧実験を行った。初期組成でH_2:He=1:1及びH_2:He=3:1の混合ガスを用意し、昨年度開発したダイヤモンドアンビルセルにガス試料を充填した。各試料について高圧下での相変化を顕微鏡下で観察し、各相のラマン散乱測定を行った。顕微鏡下の相変化観察では5.8GPaから均一流体相が水素濃集相とヘリウム濃集相の二流体相に分離し、6.5GPaで水素濃集相が固化する様子が観察された。更に加圧を続けると、ヘリウム相に対する水素溶解度が低下によると見られる、水素濃集粒子が内部に析出するのが見られた。ラマン散乱の結果からは、水素分子の伸縮運動に対応するQ1モードの圧力シフト、転移に伴う周波数の不連続変化が見られ、ヘリウム濃集相中のQ1が12.9GPaで消失する事が分かった。これは、顕微鏡観察では確認できなかったヘリウム濃集相の固化に対応すると考えられ、これらの測定はH_2:He=1:1の試料で30GPaまで、H_2:He=3:1の試料で17GPaまで行われた。以上から、固化したヘリウムに対して水素は殆ど溶解せず、高圧下では固体二相に分離すると考えられる。また、H_2:He=1:1とH_2:He=3:1の試料では、ラマンの圧力シフト量及び勾配が異なり、ヘリウム濃度依存を確認したが、過去に報告のある組成とラマンシフトの関係式とは一致しないことが分かった。本研究の結果は、過去に報告のある12GPaまでのデータに比べ2倍以上の高圧力まで観測を行い、ヘリウム固体相に対する水素の固溶量が検出限界以下であること、ラマンシフトの組成依存に関し再較正が必要なことを示した点で新しい。以上の結果は2006年度地球惑星科学関連合同大会及び、国際鉱物学会議(IMA-神戸)で報告されると共に、国際誌への投稿を準備中である。

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  • Ultra-high Pressure Earth Science of the Core and Core-Mantle Boundary

    Grant number:14102009  2002 - 2005

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (S)

    OHTANI Eiji, KONDO Tadashi, SUZUKI Akio, KUDO Tomoaki, TERASAKI Hidenori

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    Grant amount:\99580000 ( Direct expense: \76600000 、 Indirect expense:\22980000 )

    In this study we clarified the reactions occurring at the Core-Mantle boundary and structure and properties of the Earth's Core using two types of apparatuses such as a diamond anvil cell and multianvil apparatus.
    The results can be summarized as follows :
    1.We clarified the reactions between metallic iron and water up to 84 GPa and high temperatures. At pressures above 10 GPa and temperatures above 1000K, Iron and water react to form iron hydrite and iron oxide. This reaction is important during the core formation stage and at the present core-mantle boundary. This result implies that hydrogen can be incorporated into the Earth core.
    2.We have studied experimentally the reactions between metallic iron and perovskite and post-perovskite in the pressure range from 30 to 135 GPa at 3000 K which is the real Core-mantle boundary condition. We observed formation of magnesiowusite and dissolution of Si and 0 into the molten iron under the present pressure and temperature conditions. The solubility of these elements increases with increasing pressure and temperature significantly.
    3.We studied the dissolution of potassium into the molten iron under the Core conditions of 135 GPa and 3500 K. Molten iron dissolves potassium about 0.8 wt. %, and the present results showed at first that the core can contain radiogenic potassium and can produce some radiogenic heat.

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