鉄メルトの密度・弾性波速度におよぼす軽元素の影響：地球外核の軽元素の解明

2012 Fiscal Year Annual Research Report

• Project/Area Number: 23340159
• Research Institution: Osaka University
• Principal Investigator: 寺崎 英紀 大阪大学, 理学(系)研究科(研究院), 准教授 (50374898)
• Co-Investigator(Kenkyū-buntansha): 浦川 啓 岡山大学, 自然科学研究科, 准教授 (30201958)
• Project Period (FY): 2011-04-01 – 2015-03-31
• Keywords: 鉄合金 / 弾性波速度 / 密度 / 高圧 / 中心核 / 軽元素 / X線トモグラフィー / 液体

Research Abstract

地球中心核からの限られた情報である地震波データと直接比較を行うために、高温高圧下における鉄合金の密度と弾性波速度を求めることは不可欠である。昨年度に弾性波速度測定システムを導入し、トモグラフィー(CT)による密度測定と組み合わせて、高圧常温下での鉄合金固体の密度と音速の同時測定法を確立した。本年度は高温用の弾性波速度・密度測定セルを開発し、高温高圧下での合金固体および融体の弾性波速度・密度の同時測定を実施した。
・高温発生用試料セルの開発
高温下での測定を実現するために、試料部構成にグラファイト抵抗ヒーターを入れたセルを開発し、熱電対を用いて電力と温度の関係を複数の圧力条件下で調べた。また加熱時の音速測定用のシグナルケーブルへのノイズ低減のため、直流安定化電源を導入し加熱を行った。また新たにプランジャーポンプから成る油圧自動加圧装置を導入することにより、精密な加圧制御が可能となった。
・高温高圧下の合金融体の密度・音速同時測定
次に放射光X線を用いた高圧高温下での密度・弾性波速度同時測定を実施した。SPring-8 CTビームライン(BL20B2)にて、CT用80トン小型プレスで高圧発生させ測定を行った。試料にはNi-S合金を用いた。実験は、0.5-1.0 GPaの圧力において1673 Kまでの温度条件で測定を行うことができた。この結果、試料の融解とともに弾性波速度が大きく減少することが明らかとなった。さらに固体と液体で弾性波速度の温度依存性に変化が見られた。密度については融解に伴う大きな密度変化は小さいことがわかり、常圧の密度値からの傾向と良い一致を示した。これより高温高圧下における合金融体の密度と弾性波速度の同時測定が実現され、鉄合金の融点以上の温度条件でも測定できることが確認された。

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

今年度は、当初の計画通りに、高温用セルを開発し、加熱電源や自動加圧装置の導入も行い高温高圧下での密度・弾性波速度同時測定を実現させた。これを用いて合金固体および融体の測定を高温高圧下で実際に行い、固体と融体に対する物性の温度依存性の傾向を得ることができたため。

Strategy for Future Research Activity

今後は、今年度用いたシステムを使用して、数種類の鉄合金試料（Fe-C, Fe-Ni-Si, Fe-Ni, Ni-S)についての密度・弾性波速度同時測定を実施する。これより鉄合金固体および融体の密度・弾性波速度の温度・圧力・組成依存性を明らかにする。特に組成に関しては重点的に調べ、軽元素の与える鉄の密度・弾性波速度への効果および差を徹底的に調べる。得られた結果と地震波データを比較し、核中の軽元素についての評価を行う。
また技術的な点に関して、試料からのシグナルを増幅させるためにアンプを導入して信号強度取得の改善を行う。さらにオンサイトでの物性解析システムを確立し、その場で物性値が得られるようにする。

Research Products

• [Journal Article] Sound velocity measurements of liquid Fe-S at high pressure: Implications for Earth's and lunar cores (2013)
  • Author(s): Nishida, K. Y. Kono, H. Terasaki, S. Takahashi, M. Ishii, Y. Shimoyama, Y. Higo, K. Funakoshi, T. Irifune, E. Ohtani
  • Journal Title: Earth and Planetary Science Letters Volume: 362 Pages: 182-186
  • DOI: 10.1016/j.epsl.2012.11.042
  • Peer Reviewed
• [Journal Article] Interfacial tension of Fe-Si liquid at high pressure: Implications for liquid Fe-alloy droplet size in magma oceans (2012)
  • Author(s): Terasaki, H., S. Urakawa, D.C. Rubie, K. Funakoshi, T. Sakamaki, Y. Shibazaki, S. Ozawa, E. Ohtani
  • Journal Title: Physics of Earth and Planetary Interiors Volume: 202-203 Pages: 1-6
  • DOI: 10.1016/j.pepi.2012.05.002
  • Peer Reviewed
• [Journal Article] Melting relationships in the Fe-Fe3S system up to the outer core conditions (2012)
  • Author(s): Kamada, S., E. Ohtani, H. Terasaki, T. Sakai, M. Miyahara, Y. Ohishi, N. Hirao
  • Journal Title: Earth and Planetary Science Letters Volume: 359-360 Pages: 26-33
  • DOI: 10.1016/j.epsl.2012.09.038
  • Peer Reviewed
• [Journal Article] Melting relation of FeS-H system under high pressure: Implications for the core of Ganymede (2012)
  • Author(s): Shibazaki, Y., Ohtani, E., Terasaki, H.
  • Journal Title: SPring-8 Research Frontiers Volume: 2011 Pages: 102-103
• [Journal Article] Stability of Fe-Ni hydride after the reaction between Fe-Ni alloy and hydrous phase (δ-AlOOH) up to 1.2 Mbar: Possibility of H contribution to the core density deficit (2012)
  • Author(s): Terasaki,H., E.Ohtani, T.Sakai, S.Kamada, H.Asanuma, Y.Shibazaki, N.Hirao, N.Sata, Y.Ohishi, A.Suzuki, K.Funakoshi
  • Journal Title: Physics of Earth and Planetary Interiors Volume: 194-195 Pages: 18-24
  • DOI: 10.1016/j.pepi.2012.01.002
  • Peer Reviewed
• [Presentation] Sound velocity and density of liquid and solid alloys under pressure (2013)
  • Author(s): Terasaki, H., Nishida, K., Urakawa, S., Uesugi, K., Takubo, Y., Kuwabara, S., Higo, Y., Kono, Y., Kondo, T.
  • Organizer: The 3rd Global-COE international symposium on Deep Earth Mineralogy
  • Place of Presentation: Matsuyama
  • Year and Date: 20130304-20130306
  • Invited
• [Presentation] Sound velocity and density measurement of Ni-S liquid at high pressure (2013)
  • Author(s): Terasaki, H., Nishida, K., Urakawa, S., Uesugi, K., Takubo, Y., Kuwabara, S., Higo, Y., Kono, Y., Kondo, T.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] The effect of carbon content on density of liquid Fe-C at high pressure (2013)
  • Author(s): Shimoyama, Y., Terasaki, H., Ohtani, E., Urakawa, S., Takubo, Y., Nishida, K., Suzuki, A., Katayama, Y.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Density and thermophysical properties of liquid Fe-O (2013)
  • Author(s): Takubo, Y., Terasaki, H., Shimoyama, Y., Urakawa, S., Nishida, K., Kondo, T., Katayama, Y.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Sound velocities of liquid Fe-S and Fe-Si at high pressure (2013)
  • Author(s): Nishida, K., Terasaki, H., Kono, Y., Takahashi, S., Shimoyama, Y., Ushioda, M., Sakurai, M., Kuwabara, S., Higo, Y., Funakoshi, K., Ohtani, E.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Sound velocity of liquid iron alloys under Earth's core pressures by laser-shock compression (2013)
  • Author(s): Sakaiya, T., Yokoyama, N., Hosogi, R., Kondo, T., Terasaki, H., Kadono, T., Hironaka, Y, Shigemori, K.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Iron alloy-water reaction and light elements in the Earth's core (2013)
  • Author(s): Kondo, T., Yamashita, T., Yoshida, Y., Ishida, Y., Terasaki, H., Kikegawa, T.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] How much sulfur in the core (2013)
  • Author(s): Kamada, S., Ohtani, E., Terasaki, H., Fukui, H., Baron, A.Q.R., Hirao, N., Ohishi, Y.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Sound velocity of FeSi alloy at high pressure conditions by the laser-shock compression (2013)
  • Author(s): Hosogi, R., Sakaiya, T., Yokoyama, N., Kondo, T, Terasaki, H., Hironaka, Y., Shigemori, K.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Sound velocity of liquid Fe-Ni-C alloy at high pressure and temperature (2013)
  • Author(s): Kuwabara, S., Nishida, K., Terasaki, H., Funakoshi, K., Higo, Y., Ushioda, M., Sakurai, M., Kondo, T.
  • Organizer: Workshop on Approach to the centre of the Earth
  • Place of Presentation: Sendai
  • Year and Date: 20130220-20130222
• [Presentation] Development for sound velocity and density measurements of liquid metal at high pressures (2012)
  • Author(s): Terasaki, H., K. Nishida, S. Urakawa, K. Uesugi, Y. Takubo, S. Kuwabara, A. Nakatsuka, M. Hoshino, Y. Kono, Y. Higo, T. Kondo
  • Organizer: American Geophysical Union Fall meeting 2012
  • Place of Presentation: San Francisco
  • Year and Date: 20121203-20121207
• [Presentation] The Effect of oxygen on density of liquid iron at high pressure (2012)
  • Author(s): Takubo Y., Terasaki H., Shimoyama Y., Urakawa S., Suzuki A., Nishida K., Kamuro R., Kishimoto S., Kondo T., Ohtani E., Katayama Y.
  • Organizer: American Geophysical Union Fall meeting 2012
  • Place of Presentation: San Francisco
  • Year and Date: 20121203-20121207
• [Presentation] The effect of carbon content on density of liquid Fe-C at high pressure (2012)
  • Author(s): Shimoyama Y., Terasaki H., Ohtani E., Urakawa S., Takubo Y., Nishida K., Suzuki A., Katayama Y.
  • Organizer: American Geophysical Union Fall meeting 2012
  • Place of Presentation: San Francisco
  • Year and Date: 20121203-20121207
• [Presentation] Phase relations and sound velocity measurements of iron-sulfur systems at high pressure: Implications for the Earth’s core (2012)
  • Author(s): Ohtani E., Kamada S., Sakai T., Terasaki H., Shibazaki Y., Sakamaki T., Takahashi S., Sakairi T., Fukui H., Baron AQ.
  • Organizer: American Geophysical Union Fall meeting 2012
  • Place of Presentation: San Francisco
  • Year and Date: 20121203-20121207
• [Presentation] Transport of water and hydrogen into the lower mantle and core (2012)
  • Author(s): Ohtani E., Ohira I., Terasaki H.
  • Organizer: American Geophysical Union Fall meeting 2012
  • Place of Presentation: San Francisco
  • Year and Date: 20121203-20121207
  • Invited
• [Presentation] 高温高圧下における液体の密度・音速同時測定法の開発 (2012)
  • Author(s): 寺崎英紀、西田圭佑、浦川啓、上杉健太朗、星野真人、田窪勇作、桑原荘馬、近藤忠、河野義生
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪
  • Year and Date: 20121107-20121109
• [Presentation] 高温高圧下における放射光を用いた複合測定 (2012)
  • Author(s): 近藤忠、寺崎英紀、亀卦川卓美、張小威、中尾裕則
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪
  • Year and Date: 20121107-20121109
• [Presentation] 超音波法を用いた高圧下における鉄合金メルトの音速測定技術の改良 (2012)
  • Author(s): 西田圭佑、寺崎英紀、河野義生、肥後祐司、大谷栄治
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪
  • Year and Date: 20121107-20121109
• [Presentation] Dense Sulfur-rich Fe-S-F-H melt: The evolution and structure of Ganymede’s core (2012)
  • Author(s): 柴崎裕樹、大谷栄治、寺崎英紀、立山隆二、坂巻竜也、舟越賢一、肥後祐司、Yingwei Fei
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪
  • Year and Date: 20121107-20121109
• [Presentation] 高温高圧下におけるFe-Cメルトの密度 (2012)
  • Author(s): 下山裕太、大谷栄治、寺崎英紀、浦川啓、西田圭佑、田窪勇作、中塚明日美、鹿室僚太、横田育美、岸本俊八、鈴木昭夫、片山芳則
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪
  • Year and Date: 20121107-20121109
• [Presentation] 鉄融体の密度に与える酸素の効果 (2012)
  • Author(s): 田窪勇作、寺崎英紀、下山裕太、浦川啓、鈴木昭夫、西田圭佑、鹿室僚太、岸本俊八、近藤忠、大谷栄治、片山芳則
  • Organizer: 第53回高圧討論会
  • Place of Presentation: 大阪
  • Year and Date: 20121107-20121109
• [Presentation] Permeability of core-forming melt in asteroids based on in situ X-ray tomography (2012)
  • Author(s): Terasaki H., Urakawa S., Uesugi K., Ohtani E.
  • Organizer: G-COE International Symposium “Achievements of G-COE Program for Earth and Planetary Dynamics and the Future Perspective
  • Place of Presentation: Sendai
  • Year and Date: 20120925-20120928
  • Invited
• [Presentation] The dependence of pressure and temperature on liquid Fe-3.5wt%C density (2012)
  • Author(s): Shimoyama Y., Terasaki H., Ohtani E., Urakawa S., Takubo Y., Nishida K., Suzuki A.
  • Organizer: G-COE International Symposium “Achievements of G-COE Program for Earth and Planetary Dynamics and the Future Perspective
  • Place of Presentation: Sendai
  • Year and Date: 20120925-20120928
• [Presentation] 地球深部研究に向けた高圧物性測定の進展 (2012)
  • Author(s): 西原遊、寺崎英紀
  • Organizer: Spring-8シンポジウム2012
  • Place of Presentation: 大阪
  • Year and Date: 20120825-20120826
• [Presentation] 放射光X線回折法およびスペクトロスコピーを併用した地球中心部の総合的解明 (2012)
  • Author(s): 増野いづみ、大谷栄治、境毅、寺崎英紀、村上元彦、平尾直久、大石泰生
  • Organizer: Spring-8シンポジウム2012
  • Place of Presentation: 大阪
  • Year and Date: 20120825-20120826
• [Presentation] Sound velocity measurements of liquid Fe-S at high pressure (2012)
  • Author(s): Nishida K., Kono Y., Terasaki H., Takahashi S., Ishii M., Shimoyama Y., Higo Y., Funakoshi K., Irifune T., Ohtani E.
  • Organizer: Asia Oceania Geoscience Society (AOGS) – AGU(WPGM) Joint Assembly
  • Place of Presentation: Singapore
  • Year and Date: 20120813-20120817
• [Presentation] Stability of high Pressure Hydrous Delta-phase and its Roles under the Lower Mantle Conditions (2012)
  • Author(s): Ohtani E., Ohira I., Sakai T., Terasaki H., Hirao N.
  • Organizer: Asia Oceania Geoscience Society (AOGS) – AGU(WPGM) Joint Assembly
  • Place of Presentation: Singapore
  • Year and Date: 20120813-20120817
• [Presentation] Effect of sulfur on the sound velocity in liquid iron at high pressure (2012)
  • Author(s): Nishida K., Kono Y., Terasaki H., Takahashi S., Ishii M., Shimoyama Y., Higo Y., Funakoshi K., Irifune T., Ohtani E.
  • Organizer: Joint 2012 COMPRES Annual Meeting and High-Pressure Mineral Physics Seminar-8
  • Place of Presentation: Lake Tahoe, USA
  • Year and Date: 20120709-20120713
• [Presentation] Dense sulfur rich Fe-S melt: The evolution and structure of the core with Fe-S composition (2012)
  • Author(s): Shibazaki Y., Ohtani E., Terasaki H., Tateyama R., Sakamaki T., Funakoshi K.
  • Organizer: Joint 2012 COMPRES Annual Meeting and High-Pressure Mineral Physics Seminar-8
  • Place of Presentation: Lake Tahoe, USA
  • Year and Date: 20120709-20120713
• [Presentation] Hydrogen solubility into Fe-C and Fe-Si alloys at high pressure (2012)
  • Author(s): Terasaki H., Shibazaki Y., Nishida K., Takahashi S., Ishii M., Ohtani E., Higo Y.
  • Organizer: Japan Geoscience Union Meeting 2012
  • Place of Presentation: 千葉
  • Year and Date: 20120520-20120525
• [Presentation] Density measurement of liquid Fe-C at High pressure and high temperature (2012)
  • Author(s): Shimoyama Y., Ohtani E., Terasaki H., Urakawa S., Nishida K., Takubo Y., Nakatsuka A., Kamuro R., Yokota I., Kishimoto S., Katayama Y.
  • Organizer: Japan Geoscience Union Meeting 2012
  • Place of Presentation: 千葉
  • Year and Date: 20120520-20120525
• [Presentation] Sound velocity measurements of liquid Fe-S t high pressure: Implications for the Earth’s and lunar cores (2012)
  • Author(s): Nishida K., Kono Y., Terasaki H., TakahashiS., Ishii M., Shimoyama Y., Higo Y., Funakoshi K., Irihune T., Ohtani E.
  • Organizer: Japan Geoscience Union Meeting 2012
  • Place of Presentation: 千葉
  • Year and Date: 20120520-20120525
• [Presentation] Density measurement of liquid Fe-O at high pressure and high temperature using an X-ray absorption method (2012)
  • Author(s): Takubo Y., Shimoyama Y., Terasaki H., Urakawa S., Nishida K., Kamuro R., Kishimoto S., Kondo T., Ohtani E., Katayama Y.
  • Organizer: Japan Geoscience Union Meeting 2012
  • Place of Presentation: 千葉
  • Year and Date: 20120520-20120525
• [Presentation] Experimental constraints on the size of Martian liquid core (2012)
  • Author(s): Nakatsuka, A., Urakawa, S., Terasaki, H., Nishida, K., Uesugi, K., Funakoshi, K.
  • Organizer: Japan Geoscience Union Meeting 2012
  • Place of Presentation: 千葉
  • Year and Date: 20120520-20120525
• [Presentation] Neutron Camera Installed in BL11 ”PLANET” Beamline in J-PARC (2012)
  • Author(s): Inoue, T., Arima, H., Terasaki, H., Hattori, T., Sano, A
  • Organizer: Japan Geoscience Union Meeting 2012
  • Place of Presentation: 千葉
  • Year and Date: 20120520-20120525