研究者総覧

土屋 卓久 (ツチヤ タク)

  • 地球深部ダイナミクス研究センター 教授
Last Updated :2020/09/16

研究者情報

学位

  • 博士(理学)(大阪大学)

ホームページURL

J-Global ID

研究キーワード

  • さらには地球および惑星の起源と進化の解明。   地球惑星深部のダイナミックな挙動   それらの物理的性質   地球惑星深部の構造や物質構成   and origin and evolution of the Earth and planet.   mantle and core dynamics   physical and chemical property of Earth forming materials   Understanding detail structure of the deep Earth   

研究分野

  • 自然科学一般 / 固体地球科学

経歴

  • 2009年04月  愛媛大学地球深部ダイナミクス研究センター教授
  • 2007年04月 - 2009年03月  愛媛大学地球深部ダイナミクス研究センター准教授
  • 2005年04月 - 2007年03月  愛媛大学地球深部ダイナミクス研究センター助教授
  • 2001年04月 - 2004年03月  東京工業大学大学院理工学研究科日本学術振興会特別研究員PD
  • 1997年04月 - 2000年03月  大阪大学大学院理学研究科日本学術振興会特別研究員DC1

学歴

  • 1995年04月 - 1997年03月   大阪大学   大学院理学研究科   物理学専攻
  • 1991年04月 - 1995年03月   大阪大学   理学部   物理学科
  •         -   大阪大学   大学院理学研究科   宇宙地球科学専攻

所属学協会

  • アメリカ物理学会   アメリカ地球物理学連合   日本高圧力学会   日本鉱物学会   American Physical Society   American Geophysical Union   The Japan Society of High Pressure Science and Technology   The Mineralogical Society of Japan   

研究活動情報

論文

  • T. Tsuchiya, J. Tsuchiya, H. Dekura, S. Ritterbex
    Annual Review of Earth and Planetary Sciences 2020年05月 [査読有り]
     研究論文(学術雑誌)
  • Equation of state of liquid iron under extreme conditions
    Y. Kuwayama, G. Morard, Y. Nakajima, K. Hirose, A. Q. R. Baron, S.I. Kawaguchi, T. Tsuchiya, D. Ishikawa, N. Hirao, Y. Ohishi
    Physical Review Letters 2020年04月 [査読有り]
     研究論文(学術雑誌)
  • Structures of Liquid Iron–Light‐Element Mixtures under High Pressure
    S. Ohmura, T. Tsuchiya, F. Shimojo
    Physica Status Solodi B 2020年04月 [査読有り]
     研究論文(学術雑誌)
  • Viscosity of hcp iron at Earth’s inner core conditions from density functional theory
    Sebastian Ritterbex, Taku Tsuchiya
    Scientific Reports 2020年04月 [査読有り]
     研究論文(学術雑誌)
  • Ab initio thermoelasticity of liquid iron-nickel-light element alloys
    H. Ichikawa, T. Tsuchiya
    Minerals 10 2020年01月 [査読有り]
     研究論文(学術雑誌)
  • Jun Tsuchiya, Risa Nishida, Taku Tsuchiya
    Minerals 10 1 54 - 54 2020年01月 [査読有り]
     研究論文(学術雑誌)
  • Viscoelasticity of Liquid Iron at Conditions of the Earth's Outer Core
    J.-W. Xian, T. Sun, T. Tsuchiya
    Journal of Geophysical Research: Solid Earth 124 11 2019年10月 [査読有り]
     研究論文(学術雑誌)
  • Effects of Fe and Al incorporations on the bridgmanite–postperovskite coexistence domain
    X. Wang, T. Tsuchiya, Z. Zeng
    Comptes Rendus Geoscience 351 141 - 146 2019年02月 [査読有り]
     研究論文(学術雑誌)
  • Lattice thermal conductivity of MgSiO3 postperovskite under the lowermost mantle conditions from ab initio anharmonic lattice dynamics
    Haruhiko Dekura, Taku Tsuchiya
    Geophysical Research Letters 46 22 12919 - 12926 2019年 [査読有り]
     研究論文(学術雑誌)
  • Zhihua Xiong, Taku Tsuchiya, Takashi Taniuchi
    Journal of Geophysical Research: Solid Earth 123 2018年08月 [査読有り]
     研究論文(学術雑誌) 
    Potassium partitioning between molten silicates and liquid iron alloys is the fundamental process determining its incorporation into the Earth's core. In this study, it is investigated using the method of the ab initio molecular dynamics simulation combined with the thermodynamic integration technique. Results suggest that the potassium incorporation into iron alloys positively depends on temperature, while the effect of pressure is insignificant. Moreover, the existence of oxygen in liquid iron alloys significantly enhances the potassium solubility therein, whereas sulfur and silicon only have negligible effects. Electronic structure analyses reveal that potassium remains alkali‐metallic in liquid iron alloy systems under all conditions in this study, which is distinct from the characteristics reported for solid potassium. Atomic structure analyses indicate that the oxygen coordination number around potassium atom increases with oxygen concentration in liquid iron alloys, supporting the oxygen concentration dependence of the potassium partitioning between molten silicates and liquid iron alloys. Using the obtained partitioning coefficients combined with geochemical property, the maximum potassium concentration in the Earth's core is estimated to be ~30 ppm, which would be unlikely to affect the thermal evolution of the Earth's core significantly.
  • Sebastian Ritterbex, Takafumi Harada, Taku Tsuchiya
    Icarus 305 1 350 - 357 2018年05月 [査読有り]
     研究論文(学術雑誌) 
    irst-principles calculations are performed to investigate vacancy formation and migration in the B2 phase of MgO. Defect energetics suggest the importance of intrinsic non-interacting vacancy pairs, even though the extrinsic vacancy concentration might govern atomic diffusion in the B2 phase of MgO. The enthalpies of ionic vacancy migration are generally found to decrease across the B1-B2 phase transition around a pressure of 500 GPa. It is shown that this enthalpy change induces a substantial increase in the rate of vacancy diffusion in MgO of almost four orders of magnitude (∼104) when the B1 phase transforms into the B2 phase with increasing pressure. If plastic deformation is controlled by vacancy diffusion, mantle viscosity is expected to decrease in relation to this enhanced diffusion rate in MgO across the B1-B2 transition in the interior of Earth-like large exoplanets. Our results of atomic relaxations near the defects suggest that diffusion controlled creep viscosity may generally decrease across high-pressure phase transitions with increasing coordination number. Plastic flow and resulting mantle convection in the interior of these super-Earths may be therefore less sluggish than previously thought.
  • Takashi Taniuchi, Taku Tsuchiya
    Journal of Physics Condensed Matter 30 11 114003  2018年02月 [査読有り]
     研究論文(学術雑誌) 
    The melting curve of MgO is extended up to 4 TPa, corresponding to the Jovian core pressure, based on the one-step thermodynamic integration method implemented on ab initio molecular dynamics. The calculated melting temperatures are 3100 and 16 000 K at 0 and 500 GPa, respectively, which are consistent with previous experimental results, and 20 600 K at 3900 GPa, which is inconsistent with a recent experimental extrapolation, which implies the molten Jovian core. A quite small Clapeyron slope () of is found at 3900 GPa due to comparable densities of the liquid and B2 phases under extreme compression. The Mg-O coordination number in the liquid phase is saturated at around 7.5 above 1 TPa and remains smaller than that in the B2 phase (8) even at 4 TPa, suggesting no density crossover between liquid and crystal and thus no further denser crystalline phases. Dynamical properties (atomic diffusivity and viscosity) are also investigated along the melting curve to understand these behaviors in greater detail.
  • 市川浩樹, 土屋卓久
    地学雑誌 2018年 [査読有り]
     研究論文(学術雑誌)
  • 酸化マグネシウムの相転移と融解
    宮西宏併, 尾崎典雅, 丹下慶範, 土屋卓久, 兒玉了祐
    高圧力の科学と技術 2017年07月 [査読有り]
     研究論文(学術雑誌)
  • Hiroshi Fukui, Alfred Q. R. Baron, Daisuke Ishikawa, Hiroshi Uchiyama, Yasuo Ohishi, Taku Tsuchiya, Hisao Kobayashi, Takuya Matsuzaki, Takashi Yoshino, Tomoo Katsura
    JOURNAL OF PHYSICS-CONDENSED MATTER 29 24 2017年06月 [査読有り]
     研究論文(学術雑誌) 
    We investigated transverse acoustic (TA) phonons in iron-bearing magnesium oxide (ferropericlase) up to 56 GPa using inelastic x-ray scattering (IXS). The results show that the energy of the TA phonon far from the Brillouin zone center suddenly increases with increasing pressure above the spin transition pressure of ferropericlase. Ab initio calculations revealed that the TA phonon energy far from the Brillouin zone center is higher in the low-spin state than in the high spin state; that the TA phonon energy depend weakly on pressure; and that the energy gap between the TA and the lowest-energy-optic phonons is much narrower in the low-spin state than in the high-spin state. This allows us to conclude that the anomalous behavior of the TA mode in the present experiments is the result of gap narrowing due to the spin transition and explains contradictory results in previous experimental studies.
  • Haruhiko Dekura, Taku Tsuchiya
    Physical Review B 95 18 2017年05月 研究論文(学術雑誌) 
    Lattice thermal conductivity κlat of MgO at high pressures P and temperatures T up to 150 GPa and 4000 K are determined using lattice dynamics calculations and the linearized phonon Boltzmann transport equation (BTE) beyond the relaxation time approximation (RTA) from first principles. It is found that the complete solution of the linearized BTE substantially corrects values of κlat calculated with the RTA by ∼30%, from ∼42 to ∼54Wm-1K-1 under ambient conditions. The calculated values of κlat are in good agreement with those from the existing experiments. At conditions representative of the Earth's core-mantle boundary (P=136GPa and T=3800K), κlat is predicted to be ∼32 and ∼40Wm-1K-1 by RTA and the full solution of BTE, respectively. We report a detailed comparison of our study with earlier theoretical studies.
  • Haruhiko Dekura, Taku Tsuchiya
    Physical Review B 18 95 184303  2017年05月 研究論文(学術雑誌) 
    Lattice thermal conductivity κlat of MgO at high pressures P and temperatures T up to 150 GPa and 4000 K are determined using lattice dynamics calculations and the linearized phonon Boltzmann transport equation (BTE) beyond the relaxation time approximation (RTA) from first principles. It is found that the complete solution of the linearized BTE substantially corrects values of κlat calculated with the RTA by ∼30%, from ∼42 to ∼54 W m−1 K−1 under ambient conditions. The calculated values of κlat are in good agreement with those from the existing experiments. At conditions representative of the Earth’s core-mantle boundary (P = 136 GPa and T = 3800 K), κlat is predicted to be ∼32 and ∼40 W m−1 K−1 by RTA and the full solution of BTE, respectively. We report a detailed comparison of our study with earlier theoretical studies.
  • Jun Tsuchiya, Taku Tsuchiya
    The Journal of Chemical Physics 146 1 014501 - 014501 2017年01月 研究論文(学術雑誌) 
    © 2017 Author(s). The elastic constants of ice VIII and ice X phases under pressure have been determined at static 0 K conditions using first principles calculation. A step-like increase of the elastic constants of ice VIII phase occurred at 100-110 GPa due to hydrogen bond symmetrization. The elastic constants, and the pressure dependencies of these constants, of ice X and VIII are completely distinct. Due to these differences, these two phases can be distinguished on the basis of the elastic behavior. Conversely, the experimental elastic constant of C 11 of ice VII gradually changes from an ice VIII like asymmetric hydrogen bond to a symmetric bond character within a wide pressure range. This finding suggests that the transition from ice VII to ice X starts around 30 GPa and completes at 110 GPa.
  • Kohei Miyanishi, Norimasa Ozaki, Yoshinori Tange, Taku Tsuchiya, Ryosuke Kodama
    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu 27 137 - 143 2017年01月 
    © 2017, Japan Society of High Pressure Science and Technology. All rights reserved. The Hugoniot of magnesium oxide (MgO) has been investigated experimentally and computationally at the pressure range between 200 GPa and 1 TPa, where B1 and B2 structures are theoretically stable and liquid exists. The shock velocity is found to be proportional with the particle velocity up to the shock velocity of 15 km s -1 , suggesting MgO is in the B1 structure up to a shock pressure of ~350 GPa. Moreover, the Hugoniot data combined with ab initio calculations show two crossovers between the Hugoniot and an extrapolation by the linear relation around 350 GPa (and 8000 K) and 650 GPa (and 14000 K), respectively. The regions separated by the two crossovers are interpreted to be the fields of B1-B2, and B2-liquid transitions, respectively. They are consistent with the results by the ab initio calculations.
  • Nishi, M., Kuwayama, Y., Tsuchiya, J., Tsuchiya, T.
    Nature 547 7662 205 - 208 2017年 [査読有り]
     研究論文(学術雑誌) 
    © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. Water transported into Earth's interior by subduction strongly influences dynamics such as volcanism and plate tectonics. Several recent studies have reported hydrous minerals to be stable at pressure and temperature conditions representative of Earth's deep interior, implying that surface water may be transported as far as the core-mantle boundary. However, the hydrous mineral goethite, α-FeOOH, was recently reported to decompose under the conditions of the middle region of the lower mantle to form FeO 2 and release H 2, suggesting the upward migration of hydrogen and large fluctuations in the oxygen distribution within the Earth system. Here we report the stability of FeOOH phases at the pressure and temperature conditions of the deep lower mantle, based on first-principles calculations and in situ X-ray diffraction experiments. In contrast to previous work suggesting the dehydrogenation of FeOOH into FeO 2 in the middle of the lower mantle, we report the formation of a new FeOOH phase with the pyrite-Type framework of FeO 6 octahedra, which is much denser than the surrounding mantle and is stable at the conditions of the base of the mantle. Pyrite-Type FeOOH may stabilize as a solid solution with other hydrous minerals in deeply subducted slabs, and could form in subducted banded iron formations. Deep-seated pyrite-Type FeOOH eventually dissociates into Fe 2 O 3 and releases H 2 O when subducted slabs are heated at the base of the mantle. This process may cause the incorporation of hydrogen into the outer core by the formation of iron hydride, FeH x, in the reducing environment of the core-mantle boundary.
  • Sakamaki T, Ohtani E, Fukui H, Kamada S, Takahashi S, Sakairi T, Takahata A, Sakai T, Tsutsui S, Ishikawa D, Shiraishi R, 瀬戸 雄介, Tsuchiya T, Baron A
    Science Advances 2 2 DOI: 10.1126/sciadv.1500802  2016年02月 [査読有り]
     研究論文(学術雑誌)
  • Tsuchiya Taku, Kawai Kenji, Wang Xianlong, Ichikawa Hiroki, Dekura Haruhiko
    Deep Earth: Physics and Chemistry of the Lower Mantle and Core 217 13 - 30 2016年 [査読有り]
  • ハイパワーレーザー及び XFEL を用いた超高圧研究
    尾崎典雅, Albertazzi Bruno, Benuzzi-Mounaix Alessandra, Denoeud Adrien, Gregori Gianluca, 羽原英明, Hartley Nicholas, 犬伏雄一, Koenig Michel, 近藤良彦, 松岡健之, 松 山智至, 奥地拓生, 佐藤友子, 佐藤友哉, 佐野 孝好, 坂田 修 身, 瀬戸雄介, 関根利守, 田中和夫, 高橋 謙次郎, 丹下慶範, 土屋卓久, 富樫格, 矢橋牧名, 薮内俊毅, 山内和人, 兒玉了祐
    2015年11月 [査読有り]
     研究論文(その他学術会議資料等)
  • K. Miyanishi, Y. Tange, N. Ozaki, T. Kimura, T. Sano, Y. Sakawa, T. Tsuchiya, R. Kodama
    PHYSICAL REVIEW E 92 2 2015年08月 研究論文(学術雑誌) 
    Magnesium oxide has been experimentally and computationally investigated in the warm-dense solid and liquid ranges from 200 GPa to 1 TPa along the principal Hugoniot. The linear approximation between shock velocity and particle velocity is validated up to a shock velocity of 15 km/s from the experimental data, this suggesting that the MgO B1 structure is stable up to the corresponding shock pressure of similar to 350 GPa. Moreover, our Hugoniot data, combined with ab initio simulations, show two crossovers between MgO Hugoniot and the extrapolation of the linear approximation line, occurring at a shock pressures of approximately 350 and 650 GPa, with shock temperatures of 8000 and 14 000 K, respectively. These crossover regions are consistent with the solid-solid (B1-B2) and the solid-liquid (B2-melt) phase boundaries predicted by the ab initio calculations.
  • Xianlong Wang, Taku Tsuchiya, Atsushi Hase
    NATURE GEOSCIENCE 8 7 556 - U97 2015年07月 研究論文(学術雑誌) 
    The dominant minerals in Earth's lower mantle are thought to be Fe- and Al-bearing MgSiO3 bridgmanite and (Mg, Fe)O ferropericlase(1). However, experimental measurements of the elasticity of these minerals at realistic lower-mantle pressures and temperatures remain impractical. As a result, different compositional models for the Earth's lower mantle have been proposed(2-4). Theoretical simulations, which depend on empirical evaluations of the effects of Fe incorporation into these minerals, support a pyrolitic lower mantle that contains a significant amount of ferropericlase(5,6), much like the Earth's upper mantle. Here we present first-principles computations combined with a lattice dynamics approach that include the effects of Fe2+ and Fe3+ incorporation. We calculate the densities and elastic-wave velocities of several possible lower-mantle compositions with varying amounts of ferropericlase along a mantle geotherm. On the basis of our calculations of aggregate elasticities, we conclude that neither a perovskitic composition (about 9:1 bridgmanite to ferropericlase by volume) nor an olivine-like composition (about 7:3) reproduces the seismological reference model of average Earth properties. However, an intermediate volume fraction (about 8:2) consistent with a pyrolitic composition can reproduce the reference velocities and densities. Bridgmanite that is rich in ferric iron produces the best fit. Our findings support a uniform chemical composition throughout the present-day mantle, which we suggest is the result of whole-mantle convection.
  • S. Mazevet, T. Tsuchiya, T. Taniuchi, A. Benuzzi-Mounaix, F. Guyot
    PHYSICAL REVIEW B 92 1 2015年07月 研究論文(学術雑誌) 
    The physical state and properties of silicates at conditions encountered in the cores of gas giants, ice giants, and of Earth-like exoplanets now discovered with masses up to several times the mass of the Earth remain mostly unknown. Here, we report on theoretical predictions of the properties of silica, SiO2, up to 4 TPa and about 20 000 K by using first principles molecular dynamics simulations based on density functional theory. For conditions found in the super Earths and in ice giants, we show that silica remains a poor electrical conductor up to 10 Mbar due to an increase in the Si-O coordination with pressure. For Jupiter and Saturn cores, we find that MgSiO3 silicate has not only dissociated into MgO and SiO2, as shown in previous studies, but that these two phases have likely differentiated to lead to a core made of liquid SiO2 and solid (Mg,Fe)O.
  • Kenji Kawai, Taku Tsuchiya
    GEOPHYSICAL RESEARCH LETTERS 42 8 2718 - 2726 2015年04月 研究論文(学術雑誌) 
    Ca-perovskite (CaPv) is considered to be one of the most abundant minerals in the Earth's lower mantle (LM). Furthermore, previous static calculations and mean-field theory suggest that it has a much larger shear modulus than bridgmanite (MgPv). In this study, the elasticity of cubic CaPv was reinvestigated using the density functional constant-temperature first principles molecular dynamics method under the correct conditions to simulate its elasticity. Our new results clearly demonstrate that cubic CaPv has comparable bulk and slightly smaller shear moduli than Fe-bearing MgPv. This is because the boundary condition for the supercell used in this study allows for the rotational phonon motion of SiO6 octahedra under strain, which predominantly affects the decrease in C-11 and C-44. Acoustic wave velocities determined from the elastic moduli indicate that cubic CaPv has slower velocities and larger densities than Fe-bearing MgPv and preliminary reference Earth model in the LM. This suggests that if CaPv-rich material exists, it can accumulate in the lowermost LM and produce a seismically low-velocity anomaly.
  • Kenji Kawai, Taku Tsuchiya
    PHYSICS OF THE EARTH AND PLANETARY INTERIORS 240 125 - 131 2015年03月 研究論文(学術雑誌) 
    We study the high-pressure stability and elastic properties of Mg3Al2Si3O12 Pyrope garnet using the density functional first principles computation method. Pyrope garnet is found to dissociate into an assemblage of MgSiO3 Mg-perovskite (Pv) and Al2O3 corundum (Cor) solid solutions at similar to 19.7 GPa at static conditions. Then, this assemblage undergoes a phase transition to pyropic (Al-bearing) Pv at similar to 65 GPa. The enthalpy of an assemblage of MgAl2O4 calcium ferrite (CF), MgPv, and stishovite (St) is less stable than that of MgPv plus Cor. A continuous reaction in the MgSiO3-Al2O3 system suggested by this study is consistent with previous experimental and computational studies but not with a recently modeled phase diagram. This implies that the formation of pyropic Pv could not cause any seismic scatterers in the mid-lower mantle. The investigated anisotropy of elastic velocities further indicates that pyrope garnet is a very isotropic mineral. Our results suggest that seismological anisotropy inferred in the upper mantle could not be due to garnet. (C) 2014 Elsevier B.V. All rights reserved.
  • 超高圧下における酸化マグネシウムの屈折率計測
    宮西宏併, 尾崎典雅, 丹下慶範, 出倉春彦, 木村友亮, 坂和洋一, 佐野孝好, 土屋卓久, 兒玉了祐
    レーザー学会誌 レーザー研究 43 41 - 45 2015年01月 [査読有り]
     研究論文(学術雑誌)
  • Kenji Kawai, Taku Tsuchiya
    The Earth's Heterogeneous Mantle: A Geophysical, Geodynamical, and Geochemical Perspective 259 - 274 2015年01月 [査読有り]
     論文集(書籍)内論文 
    The fate and amount of granitic materials subducted into the deep mantle are still under debate. The density, elastic property, and phase stability of granitic materials in the mantle pressures are key to clarifying them. Here, we modeled highpressure properties of the granitic assemblage by using ab initio mineral physics data of grossular garnet, K-hollandite, jadeite, stishovite, and calcium ferrite (CF)-type phase. We find that the ongoing subducting granitic assemblage, such as sediments and average upper crust rocks, is much denser than pyrolite in the pressure range from 9 GPa (~270 km), at which coesite undergoes a phase transition to stishovite, to around 27 GPa (~740 km). Above this pressure, granitic material becomes less dense than a pyrolite. This indicates that the granitic assemblage becomes gravitationally stable at the base of the mantle transition zone (MTZ). Results suggest a possibility that the granitic materials could accumulate around the 740 km depth if carried into the depth deeper than 270 km and segregated at some depth. Comparison of the velocities between granitic and pyrolitic materials shows that granitic materials can produce substantial velocity anomalies in the MTZ and the uppermost lower mantle (LM). Seismic observations such as anomalously fast velocities, especially for the shear wave, around the 660-km discontinuity, the complexity of 660-km discontinuity, and the scatterers in the uppermost LM could be associated with the subducted granitic materials.
  • Hitoshi Yusa, Taku Tsuchiya, Masaki Akaogi, Hiroshi Kojitani, Daisuke Yamazaki, Naohisa Hirao, Yasuo Ohishi, Takumi Kikegawa
    INORGANIC CHEMISTRY 53 21 11732 - 11739 2014年11月 [査読有り]
     研究論文(学術雑誌) 
    The postperovskite phase of ZnGeO3 was confirmed by laser heating experiments of the perovskite phase under 110-130 GPa at high temperature. Ab initio calculations indicated that the phase transition occurs at 133 GPa at 0 K. This postperovskite transition pressure is significantly higher than those reported for other germanates, such as MnGeO3 and MgGeO3. The comparative crystal chemistry of the perovskite-to-postperovskite transition suggests that a relatively elongated b-axis in the low-pressure range resulted in the delay in the transition to the postperovskite phase. Similar to most GdFeO3-type perovskites that transform to the CaIrO3-type postperovskite phase, ZnGeO3 perovskite eventually transformed to the CaIrO3-type postperovskite phase at a critical rotational angle of the GeO6 octahedron. The formation of the postperovskite structure at a very low critical rotational angle for MnGeO3 suggests that relatively large divalent cations likely break down the corner-sharing GeO6 frameworks without a large rotation of GeO6 to form the postperovskite phase.
  • Hugoniot Measurement of MgO up to 1 Tpa
    丹下慶範, 宮西宏平, 尾崎典雅, 佐野孝好, 坂和洋一, 土屋卓久, 兒玉了祐
    2014年03月
  • Xianlong Wang, Taku Tsuchiya
    AMERICAN MINERALOGIST 99 2-3 387 - 392 2014年02月 [査読有り]
     研究論文(学術雑誌) 
    We systematically investigated the L-edge X-ray emission spectroscopy (XES), a 3d-to-2p transition, of Fe2+- and Fe3+-bearing MgSiO3 perovskite under high pressure based on the internally consistent LSDA+U technique combined with the Slater-transition method. The Fe L-edge XES spectra can be used to directly interpolate the distribution of Fe-3d electrons including the spin states and coordination environments of iron. Our results show that the spin transition from the high-spin state to low-spin state of Fe2+ and Fe3+ can be identified easily by the L-edge XES technique. The valence state of Fe (2+ or 3+) can be verified by this, since a shift of the first main peak of Fe2+ across the spin transition of 2 eV, in good agreement with the experimental value (similar to 1.6 eV), is significantly smaller than that of Fe3+ of 4 eV. The width of the L-edge XES of Fe3+ also depends strongly on the substitution sites (Mg or Si), meaning that its coordination environments might also be distinguishable based on the Fe L-edge XES spectra. These strong sensitivities to the Fe's states suggest that the high-resolution Fe L-edge XES would be a useful experimental technique to investigate Fe-bearing silicate minerals.
  • Kenji Kawai, Taku Tsuchiya
    Journal of Geophysical Research: Solid Earth 119 4 2801 - 2809 2014年 [査読有り]
     研究論文(学術雑誌) 
    Ca-perovskite (Pv) is considered to be one of the most abundant minerals in the Earth's lower mantle (LM) with an ideal cubic structure at LM pressures and temperatures. In this study, a pressure-volume-temperature (P-V-T) equation of state model for Ca-Pv is constructed using density functional first-principles molecular dynamics simulations. The calculated P-V-T data yield KT01000K = 203.95 GPa, V01000K = 46.17 Å3/formula unit, γ0 = 1.576, and q = 0.96 within the framework of the Mie-Grüneisen-Debye formulation. We compare the density and bulk sound velocity of Ca-Pv with those of iron-bearing Mg-Pv and seismological values. Along an adiabatic temperature gradient, Ca-Pv has ~2.5% higher density and ~0.7% faster bulk sound velocity than the preliminary reference Earth model, while it has ~3.8% higher density and ~2.7% slower bulk sound velocity than iron-bearing Mg-Pv. Our results indicate that a possible lateral variation in the Ca-Pv fraction in the LM could produce an anticorrelation between V Φ and ρ. ©2014. American Geophysical Union. All Rights Reserved.
  • Riko Iizuka, Takehiko Yagi, Kazuki Komatsu, Hirotada Gotou, Taku Tsuchiya, Keiji Kusaba, Hiroyuki Kagi
    AMERICAN MINERALOGIST 98 8-9 1421 - 1428 2013年08月 [査読有り]
     研究論文(学術雑誌) 
    The crystal structure of a high-pressure phase of calcium hydroxide, Ca(OH)(2) (portlandite), was clarified for the first time using the combination of in situ single-crystal and powder X-ray diffraction measurements at high pressure and room temperature. A diamond-anvil cell with a wide opening angle and cell-assembly was improved for single-crystal X-ray diffraction experiments, which allowed us to successfully observe Bragg reflections in a wide range of reciprocal space. The transition occurred at 6 GPa and the crystal structure of the high-pressure phase was determined to be monoclinic at 8.9 GPa and room temperature [I121; a = 5.8882(10), b = 6.8408(9), c = 8.9334(15) angstrom, beta = 104.798(15)degrees]. The transition involved a decrease in molar volume by approximately 5.8%. A comparison of the structures of the low- and high-pressure phases indicates that the transition occurs by a shift of CaO6 octahedral layers in the a-b plane along the a-axis, accompanied by up-and-down displacements of Ca atoms from the a-b plane. The crystal structure of this high-pressure phase is considered to be an intermediate state between the low-pressure phase and the high-pressure-high-temperature phase. The complicated diffraction patterns of the high-pressure phase suggest that the phase transition occurred toward three directions around the c-axis of the low-pressure phase. This explains the difficulties encountered in previous structural analyses. The present results will provide key information for discussing the behavior of hydrogen bonds in these hydrous minerals under pressure.
  • Taku Tsuchiya, Kenji Kawai, Shigenori Maruyama
    GEOSCIENCE FRONTIERS 4 3 341 - 347 2013年05月 [査読有り]
     研究論文(学術雑誌) 
    The Earth was born from a giant impact at 4.56 Ga. It is generally thought that the Earth subsequently cooled, and hence shrunk, over geologic time. However, if the Earth's convection was double-layered, there must have been a peak of expansion during uni-directional cooling. We computed the expansion-contraction effect using first principles mineral physics data. The result shows a radius about 120 km larger than that of the present Earth immediately after the consolidation of the magma-ocean on the surface, and subsequent shrinkage of about 110 km in radius within about 10 m.y., followed by gradual expansion of 11 km in radius due to radiogenic heating in the lower mantle in spite of cooling in the upper mantle in the Archean. This was due to double-layered convection in the Archean with final collapse of overturn with contraction of about 8 km in radius, presumably by the end of the Archean. Since then, the Earth has gradually cooled down to reduce its radius by around 12 km. Geologic evidence supports the late Archean mantle overturn ca. 2.6 Ga, such as the global distribution of super-liquidus flood basalts on nearly all cratonic fragments (>35 examples). If our inference is correct, the surface environment of the Earth must have undergone extensive volcanism and emergence of local landmasses, because of the thin ocean cover (3-5 km thickness). Global unconformity appeared in cratonic fragments with stromatolite back to 2.9 Ga with a peak at 2.6 Ga. The global magmatism brought extensive crustal melting to yield explosive felsic volcanism to transport volcanic ash into the stratosphere during the catastrophic mantle overturn. This event seems to be recorded by sulfur mass-independent fractionation (SMIF) at 2.6 Ga. During the mantle overturn, a number of mantle plumes penetrated into the upper mantle and caused local upward doming of by ca. 2-3 km which raised local landmasses above sea-level. The consequent increase of atmospheric oxygen enabled life evolution from prokaryotes to eukaiyotes by 2.1 Ga, or even earlier in the Earth history. (C) 2013, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.
  • Exploring High-energy Density Material with High-Power Laser
    N. Ozaki, G. Gregori, H. Uranishi, A. Benuzzi-Mounaix, K. Falk, Y. Inubushi, T. Kimura, M. Koenig, M. Makita, K. Miyanishi, C. Murphy, D. Riley, T. Sano, Y. Sakawa, T. Tsuchiya, T. Vinci, R. Kodama
    2013年04月
  • Taku Tsuchiya, Kenji Kawai
    Physics and Chemistry of the Deep Earth 213 - 243 2013年03月 [査読有り]
     論文集(書籍)内論文 
    Recent progress in theoretical mineral physics based on the ab initio quantum mechanical computation method has been dramatic in conjunction with the rapid advancement of computer technologies. This chapter briefly reviews recent progress in studying high-pressure elasticity of lower mantle minerals including silicates, oxides, and some hydrous phases, and then summarizes current knowledge on the aggregate elasticity of representative lithology closely related to the mantle and slab materials. The analyses presented in the chapter indicate that the pyrolitic composition can describe the Earth's properties quite well in terms of density, P and S wave velocity, and bulk sound velocity. The overall agreements are better than those expected in more silicic compositions. Computations also suggest that cumulated basaltic piles are unsuitable to explain the LLSVP. © 2013 John Wiley & Sons, Ltd.
  • パワーレーザーを用いた極超高圧力ショック下の物質の振舞いに関する実験的研究
    尾崎典雅, 兒玉了祐, 佐野智一, 宮西宏併, 浦西宏幸, Gianluca GREGORI, Katerina FALK, Thomas WHITE, 関根利守, 犬伏雄一, 木村友亮, 土屋卓久, 佐野孝好, 坂和洋一, Alessandra BENUZZI-MOUNAIX,Michel KOENIG, David RILEY, 牧田美香子
    2013年03月 研究論文(その他学術会議資料等)
  • Taku Tsuchiya, Xianlong Wang
    Journal of Geophysical Research: Solid Earth 118 1 83 - 91 2013年01月 [査読有り]
     研究論文(学術雑誌) 
    High-pressure (P) and high-temperature (T) thermodynamics and spin transition of Fe3+-bearing MgSiO3 perovskite (Pv) are investigated by means of the internally consistent LDA + U method combined with the lattice dynamics method. Fe3+ is found to contribute mainly to the low frequency phonons. The spin transition of iron in the B site occurs at 55 GPa at 300 K and from ~75 to ~90 GPa at lower mantle temperatures. Although high-spin Fe3+ expands the volume of Pv, most of the bulk thermodynamic properties of Pv are insensitive to Fe3+ incorporation at least at XFe2O3 = 0.0625, with the exception of the Grüneisen parameter. The calculated properties are in good agreement with room temperature experimental data, but a significant increase suggested in the isothermal bulk modulus is not predicted. Results clearly demonstrate that Fe3+-bearing perovskite alone does not reproduce the density and the bulk sound velocity of the Earth's lower mantle simultaneously. Key Points The spin transition of Fe3+ in Pv occurs from ~75 GPa to ~90 GPa at ~2000 K Most of the thermodynamic properties of Pv are insensitive to Fe3+ Fe3+-bearing Pv alone does not reproduce the Earth's rho and Vf simultaneously ©2012. American Geophysical Union. All Rights Reserved.
  • Arnaud Metsue, Taku Tsuchiya
    PROCEEDINGS OF THE JAPAN ACADEMY SERIES B-PHYSICAL AND BIOLOGICAL SCIENCES 89 1 51 - 58 2013年01月 [査読有り]
     研究論文(学術雑誌) 
    We investigate the shear response of possible slip systems activated in pure and Fe-bearing MgSiO3 post-perovskite (PPv) through ab initio generalized stacking fault (GSF) energy calculations. Here we show that the [100](001) slip system has the easiest response to plastic shear among ten possible slip systems investigated. Incorporation of Fe2+ decreases the strength of all slip systems but does not change the plastic anisotropy style. Therefore, pure and Fe-bearing MgSiO3 PPv should demonstrate similar LPO patterns with a strong signature of the [100](001) slip system. An aggregate with this deformation texture is expected to produce a V-SH > V-SV type polarization anisotropy, being consistent with seismological observations.
  • Kenji Kawai, Shinji Yamamoto, Taku Tsuchiya, Shigenori Maruyama
    GEOSCIENCE FRONTIERS 4 1 1 - 6 2013年01月 [査読有り]
     研究論文(学術雑誌) 
    It has been thought that granitic crust, having been formed on the surface, must have survived through the Earth's evolution because of its buoyancy. At subduction zones continental crust is predominantly created by arc magmatism and is returned to the mantle via sediment subduction, subduction erosion, and continental subduction. Granitic rocks, the major constituent of the continental crust, are lighter than the mantle at depths shallower than 270 km, but we show here, based on first principles calculations, that beneath 270 km they have negative buoyancy compared to the surrounding material in the upper mantle and transition zone, and thus can be subducted in the depth range of 270-660 km. This suggests that there can be two reservoirs of granitic material in the Earth, one on the surface and the other at the base of the mantle transition zone (MTZ). The accumulated volume of subducted granitic material at the base of the MTZ might amount to about six times the present volume of the continental crust. Our calculations also show that the seismic velocities of granitic material in the depth range from 270 to 660 km are faster than those of the surrounding mantle. This could explain the anomalous seismic-wave velocities observed around 660 km depth. The observed seismic scatterers and reported splitting of the 660 km discontinuity could be due to jadeite dissociation, chemical discontinuities between granitic material and the surrounding mantle, or a combination thereof. (C) 2012, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved.
  • Kenji Kawai, Taku Tsuchiya
    AMERICAN MINERALOGIST 98 1 207 - 218 2013年01月 [査読有り]
     研究論文(学術雑誌) 
    To understand the fate of the host phase for potassium subducted into the deep Earth's interior, we have studied the high-pressure stability and elastic properties of KAlSi3O8 hollandite (K-hollandite) by means of the first-principles computation method. Based on experimental observations, the tetragonal K-hollandite I phase was found to undergo a ferroelastic second-order phase transition to the monoclinic K-hollandite II phase at 14.9 GPa. This K-hollandite II phase was mechanically stable up to 150 GPa (i.e., entirely in the Earth's lower mantle), being consistent with previous studies. The Born's elastic stability criteria indicate that the tetragonal mechanical instability occurs at similar pressure of 16.9 GPa with shear softening. This causes anomalous pressure dependence of the wave velocities across the instability. Taking a Clapeyron slope of 7 MPa/K and a temperature of 1800 K, the transition pressure becomes similar to 28 GPa corresponding to about 770 km depth, which would be seismologically detectable and could be comparable to seismic scatterers observed at the shallowest lower mantle. Next, we studied the solid-solution effect of sodium to K-hollandite, indicating that it is very limited on the phase stability, although the Na-end-member phase was found to be metastable. Elasticity demonstrates strong anisotropy around 15 GPa due to its ferroelastic nature.
  • Renata M. Wentzcovitch, Koichiro Umemoto, Taku Tsuchiya, Jun Tsuchiya
    Post-Perovskite: The Last Mantle Phase Transition 79 - 97 2013年 [査読有り]
     研究論文(学術雑誌) 
    A high-pressure phase transition in iron free MgSiO3 perovskite (pv), the most abundant Earth forming mineral phase, was discovered and reported in 2003- 2004. A subsequent dissociation transition in the newly found polymorph was predicted in 2006. Here, we summarize our theoretical and computational studies of these phase transitions and of the physical properties of the newly found postperovskite (ppv) and post-ppv phases. Our approach is based on density functional theory, on the plane-wave pseudopotential method, and on quasiharmonic free energy computations. We focus here on the structural, vibrational, and thermodynamic properties, and on the stability field of the ppv phase. The predicted Clapeyron slope of the ppv transition and several properties of the ppv phase strongly suggest that this is an important candidate for a primary constituent in D". We also review the post-ppv transition and the properties of the resulting aggregate. They are important for modeling and advancing our understanding of the mantle of terrestrial exoplanets and of the gas giants' cores.
  • Dekura, H., Tsuchiya, T., Tsuchiya, J.
    Physical Review Letters 110 2 2013年 研究論文(学術雑誌) 
    The lattice thermal conductivity (κlat) of MgSiO 3 perovskite (Mg-Pv) under high-pressure and high-temperature conditions was computed based on the ab initio anharmonic lattice dynamics method with the density functional perturbation theory. κlat of Mg-Pv is found to increase with increasing pressure from 9.8 (at 23.5 GPa) to 43.6 W m-1 K-1 (at 136 GPa) at 300 K, while decreasing with increasing temperature from 28.1 (at 300 K) to 2.3 W m-1 K -1 (at 4000 K) at 100 GPa. A multiphase composite average yielded a mantle Rayleigh number adequate to promote the vigorous thermal convection of the mantle that is expected geophysically. © 2013 American Physical Society.
  • Hiroshi Fukui, Taku Tsuchiya, Alfred Q. R. Baron
    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 117 12 2012年12月 [査読有り]
     研究論文(学術雑誌) 
    Vibrational densities of states and phonon dispersion relations for Mg0.875Fe0.125O ferropericlase in the high- and low-spin (HS and LS) states were calculated from first principles lattice dynamics using the internally consistent LDA+U technique. Finite-temperature thermodynamic properties were determined based on the quasi-harmonic approximation including the HS and LS mixing entropy and the magnetic entropy effects, which gave pressure and temperature variations of the low-spin fraction. Our results suggest that for thermodynamic modeling of the earth's interior, the effect of the mixed spin state cannot be ignored in the lower mantle, especially the lowermost part. The anomaly in the seismic wave velocity due to the spin crossover transition of ferropericlase, if it exists, is difficult to detect because of the wide pressure range of the transition, which is broadened by the temperature effect and the damping of the amplitude of the slow seismic wave. Citation: Fukui, H., T. Tsuchiya, and A. Q. R. Baron (2012), Lattice dynamics calculations for ferropericlase with internally consistent LDA+U method, J. Geophys. Res., 117, B12202, doi: 10.1029/2012JB009591.
  • Arnaud Metsue, Taku Tsuchiya
    GEOPHYSICAL JOURNAL INTERNATIONAL 190 1 310 - 322 2012年07月 [査読有り]
     研究論文(学術雑誌) 
    The thermodynamic properties of (Mg0.9375Fe2+0.0625)SiO3 perovskite have been investigated at the pressure and temperature conditions of the lower mantle by first-principles calculations where iron is incorporated in the high and low-spin states for the first time. The electronic structure of ferrous Fe-bearing perovskite is modelled within the internally consistent local spin density approximation with a Hubbard correction U. The thermodynamic properties are derived from the calculation of the Helmholtz free energy within the quasi-harmonic approximation, which requires the phonon frequencies determined by direct calculations of the dynamic matrices. Incorporation of iron, irrespective of its spin states, decreases the acoustic phonon mode frequencies, but less affects high-energy optic modes, leading to decreasing of the acoustic wave velocities in Fe-bearing MgSiO3 perovskite, consistent with previous studies on the elasticity of this phase. This study suggests that the thermodynamic properties of silicate perovskite, such as the equation of state and isothermal bulk modulus, are not largely modified by the incorporation of 6.25 per cent of ferrous iron. Calculations of the static enthalpy of the iron-bearing perovskite in the 0150-GPa-pressure range demonstrate that low-spin ferrous iron is unstable at the pressure conditions of the lower mantle. Finally, we clarify the perovskite-to-post-perovskite phase transition boundary in an (Mg0.9375Fe0.0625)SiO3 composition. Ferrous iron is found to decrease the transition pressure between the two phases with a small binary phase loop of 34 GPa at the lowermost mantle conditions from 111 to 115 GPa at 2500 K and from 116 to 119 GPa at 3000 K.
  • Kenji Kawai, Taku Tsuchiya
    PHYSICS AND CHEMISTRY OF MINERALS 39 4 305 - 310 2012年04月 [査読有り]
     研究論文(学術雑誌) 
    Vibrational density of states of the NaAlSi2O6 jadeite and NaAlSiO4 calcium ferrite (CF)-type, and SiO2 stishovite is calculated as a function of pressure up to 50 GPa using density functional perturbation theory. The calculated frequencies are used to determine the thermal contribution to the Helmholtz free energy within the quasi-harmonic approximation and to derive the equation of state and several thermodynamic properties of interest. A dissociation of jadeite into a mixture of a CF-type phase and stishovite is predicted to occur at 23.4 GPa and 1,800 K with a positive Clapeyron slope of 2.8 MPa/K. Elastic anisotropy for jadeite, the CF-type phase, and stishovite also computed clearly shows that stishovite and the CF-type phase are the most anisotropic and isotropic in these three phases, respectively.
  • Arnaud Metsue, Taku Tsuchiya
    PHYSICS AND CHEMISTRY OF MINERALS 39 3 177 - 187 2012年03月 [査読有り]
     研究論文(学術雑誌) 
    In this study, we report the elastic properties of three ultrahigh-pressure phases of SiO2: pyrite, cotunnite and Fe2P types between 300 and 1,500 GPa calculated by means of the density functional ab initio method. It is generally thought that materials tend to be more compact and isotropic with increasing pressure. These three ultrahigh-pressure phases of silica are mechanically stable in the investigated pressure range according to the Born criteria, while the cotunnite and Fe2P types are unstable at lower pressure. The elastic azimuthal anisotropy of these ultrahigh-pressure phases of silica shows that all the structures counterintuitively have considerable anisotropies even at multimegabar pressures. Among the three investigated structures, the cotunnite type of SiO2 is the most elastically anisotropic phase due to a soft compression along the b axis combined with a large distortion of the polyhedrons that make the structure. This might also be related to its thermodynamic unfavorability compared to the Fe2P type under extreme pressure condition. The bond property analyses clearly show that the Si-O bond remains an ionic-covalent mixed bond even at multimegabar pressures with an invariable ionicity with pressure. This argument can explain the monotonously pressure dependence of the elastic anisotropy in the case of pyrite, while the changes in the velocity distribution patterns out of the thermodynamic instability range largely contribute to those of the cotunnite and Fe2P types.
  • Kenji Kawai, Taku Tsuchiya
    AMERICAN MINERALOGIST 97 2-3 305 - 314 2012年02月 [査読有り]
     研究論文(学術雑誌) 
    New hexagonal aluminous (NAL) phase and orthorhombic calcium-ferrite (CF) type phase are considered to be major mantle components of the mid-ocean ridge basalt (MORB) at pressure and temperature conditions in the lower mantle, which can potentially host alkali elements with large ionic radii. The high-pressure stability and elastic properties of both NAL and CF phases are therefore of fundamental importance for understanding the fate of subducted MORB. Here we report those properties of the NaMg2Al5SiO12 system studied by means of the first-principles computation method. NAL was found to transform to the CF phase at 39.6 G Pa, accompanied by discontinuities in density (+1.8%), as well as compressional wave (-0.2%), shear wave (+0.9%), and bulk sound (-1.0%) velocities. The property of subducted MORB was evaluated using these results, and the velocity contrast between pyrolite and MORB of similar to-5% was found to be quite comparable to the shear velocity anomaly observed for seismic scatterers at depths from 1100 to 1800 km. However, since the transformation of the NAL to CF phase within MORB produces insignificant increases in the seismic velocities, it would be seismologically undetectable. On the other hand, the anisotropy change associated with the phase transition is significant and could be seismically detectable using observations such as shear wave splitting measurements since the CF phase is considerably more anisotropic compared to the NAL phase.
  • Kenji Kawai, Taku Tsuchiya
    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 117 2012年02月 [査読有り]
     研究論文(学術雑誌) 
    In order to understand the fate of subducted continental materials by means of mechanisms such as tectonic erosion and sediment subduction, it is important to understand the high-pressure stability and elastic properties of grossular garnet. We study these questions using the first principles computation method. Grossular garnet was found to dissociate into an assemblage of CaSiO3 Ca-perovskite (Pv) and Al2O3 corundum (Cor) at about 23.4 GPa, accompanied by remarkable jumps of compressional wave (8.0%), shear wave (11.6%), bulk sound (5.7%) velocities, and density (12.1%). Although Pv with the grossular garnet composition was suggested experimentally after the decomposition reaction, this phase was found to be less stable than an assemblage of CaPv and Cor at pressures higher than 20 GPa. This indicates that observed Pv with the grossular garnet composition is metastable but can be obtained because of the slow kinetics of the garnet decomposition reaction. Our results imply that the dissociation of grossular garnet (as well as that of jadeite) included in continental materials subducted into the deep mantle increases the complexity of the 660 km discontinuity and can explain seismically observed multiple reflections. We have also investigated the anisotropy of elastic velocities of grossular garnet, CaPv, and Cor and found that CaPv is the most anisotropic mineral. This implies that CaPv could produce seismic anisotropy in the uppermost lower mantle.
  • Taku Tsuchiya
    PHYSICS OF THE EARTH AND PLANETARY INTERIORS 188 3-4 142 - 149 2011年10月 研究論文(学術雑誌) 
    The origin of the large low velocity structures observed in the lowermost mantle is still unclear. To make new insights into deep mantle heterogeneity, we performed ab initio modeling of the elasticity of representative petrology with the pyrolitic and basaltic compositions based on the elasticities of the following mineral phases: magnesium silicate perovskite (post-perovskite), ferropericlase, calcium silicate perovskite, stishovite (CaCl2), and calcium ferrite (titanate)-type MgAl2O4. Calculations elucidated that the basalt composite is similar to 2% denser than the pyrolitic one through all of the pressures in the lower mantle. In addition, the shear (V-S) and bulk sound (V-Phi) velocities were found to be similar to 2% slower and faster in the basalt composition in particular at similar to 30 GPa and >120 GPa respectively, while both the pyrolitic and basaltic composites have almost the same compressional wave speed (V-P). Thermochemically distinct piles which are thought to be related to accumulated hot and dense subducted crusts would therefore be expected to produce as much as a -5% to -6% low velocity anomaly in the S wave but only similar to-1% in the P wave. These suggest that the basaltic pile seems less compatible to the seismological signatures of the large low velocity structures, if accompanied by thermal anomalies reaching +1000 to +1500 K. (C) 2011 Elsevier B.V. All rights reserved.
  • Arnaud Metsue, Taku Tsuchiya
    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 116 2011年08月 研究論文(学術雑誌) 
    Phonon dispersion relations and vibrational density of states of (Mg0.9375Fe0.0625)SiO3 postperovskite have been determined by direct first-principles calculations of the dynamical matrix up to 150 GPa. Incorporation of iron in the postperovskite phase, irrespective of the two investigated configurations and the spin state, was found to decrease the acoustic phonon frequencies but to have a minor effect on the optic modes at high frequencies. The phonon dispersion curves exhibit negative phonon frequencies below 10 GPa when iron is incorporated in the high or low spin state and indicate unstable dynamic structures. Then, the calculated phonon frequencies of dynamically stable structures are used to determine vibrational contributions to the Helmholtz free energy within the quasi-harmonic approximation. The high temperature equation of state and several thermodynamic properties are then derived for (Mg0.9375Fe0.0625)SiO3 postperovskite and compared with those of pure MgSiO3 postperovskite. The results show that a low concentration of iron, irrespective of high spin or low spin, in MgSiO3 postperovskite has a minor effect on the thermodynamic properties at pressure-temperature conditions of the lowermost part of the Earth's mantle.
  • Jun Tsuchiya, Taku Tsuchiya
    Physical Review B - Condensed Matter and Materials Physics 83 13 2011年 [査読有り]
     研究論文(学術雑誌)
  • Dekura, H., Tsuchiya, T., Kuwayama, Y., Tsuchiya, J.
    Physical Review Letters 107 4 2011年 研究論文(学術雑誌)
  • 石河 孝洋, 土屋 卓久
    日本高圧力学会高圧力の科学と技術 accepted 2011年
  • Ishikawa, T., Tsuchiya, T., Tsuchiya, J.
    Physical Review B - Condensed Matter and Materials Physics 83 21 212101  2011年 研究論文(学術雑誌)
  • Dekura, H., Tsuchiya, T., Tsuchiya, J.
    Physical Review B - Condensed Matter and Materials Physics 83 13 134114  2011年 研究論文(学術雑誌)
  • Tsuchiya, J., Tsuchiya, T.
    Physical Review B - Condensed Matter and Materials Physics 83 5 054115  2011年 研究論文(学術雑誌)
  • 日本結晶学会日本結晶学会誌 53 1 2 - 7 2011年
  • 東京地学協会地学雑誌 119 6 1197 - 1214 2011年
  • Tsuchiya, T., Tsuchiya, J.
    Proceedings of the National Academy of Sciences of the United States of America 108 4 1252 - 1255 2011年 研究論文(学術雑誌)
  • 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年01月 研究論文(学術雑誌) 
    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's core may be composed of an Fe-S-H system. According to our results, hydrogen dissolved in Ganymede's core lowers the melting temperature of the core composition, and so today, the core could have solid 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.
  • Yusuke Usui, Taku Tsuchiya
    JOURNAL OF EARTH SCIENCE 21 5 801 - 810 2010年10月 研究論文(学術雑誌) 
    Ab initio two-phase molecular dynamics simulations were performed on silica at pressures of 20-160 GPa and temperatures of 2 500-6 000 K to examine its solid-liquid phase boundary. Results indicate a melting temperature (T-m) of 5 900 K at 135 GPa. This is 1 100 K higher than the temperature considered for the core-mantle boundary (CMB) of about 3 800 K. The calculated melting temperature is fairly consistent with classical MD (molecular dynamics) simulations. For liquid silica, the O-O coordination number is found to be 12 along the T-m and is almost unchanged with increasing pressure. The self-diffusion coefficients of O and Si atoms are determined to be 1.3x10(-9)-3.3x10(-9) m(2)/s, and the viscosity is 0.02-0.03 Pas along the T-m. We find that these transport properties depend less on pressure in the wide range up of more than 135 GPa. The eutectic temperatures in the MgO-SiO2 systems were evaluated and found to be 700 K higher than the CMB temperature, though they would decrease considerably in more realistic mantle compositions.
  • Kenji Kawai, Taku Tsuchiya
    GEOPHYSICAL RESEARCH LETTERS 37 17 L17302  2010年09月 研究論文(学術雑誌) 
    Subducted crusts contain aluminous phases with incompatible elements such as sodium. In order to understand the fate of subducted crusts and how they recycle within the Earth, it is important to investigate high-pressure stability and elastic properties of host phases. Here we have studied NaAlSi2O6 jadeite, a NaAlSiO4 calcium ferrite (CF)-type phase, and SiO2 stishovite by means of a first principles computation method. Jadeite was found to dissociate into an assemblage of the CF-type phase and stishovite at about 18 GPa, associated with remarkable increases of compressional wave (18.7%), shear wave (26.4%), bulk sound (13.3%) velocities, and density (15.1%). Proximity of this transition condition to the 660 km discontinuity in the mantle transition zone suggests that seismically observed splitting of the reflection could be related to this phase transition, implying subduction of crustal materials down to the mantle transition zone. Citation: Kawai, K., and T. Tsuchiya (2010), Ab initio investigation of high-pressure phase relation and elasticity in the NaAlSi2O6 system, Geophys. Res. Lett., 37, L17302, doi: 10.1029/2010GL044310.
  • Hitoshi Yusa, Taku Tsuchiya, Nagayoshi Sata, Yasuo Ohishi
    INORGANIC CHEMISTRY 49 10 4478 - 4485 2010年05月 研究論文(学術雑誌) 
    In situ X-ray diffraction experiments and ab initio calculations elucidated the high-pressure phase transition properties of yttrium sesquioxides. The C-, B-, and A-type sesquioxides structure sequence observed in the room-temperature compression does not coincide with the high-pressure phase sequence of yttrium sesquioxides at high temperature. A reconstructive-type transformation taking place at high temperature yields the Gd2S3 structure around 8 GPa with a drastic change in cation-oxygen coordinations. Ab initio structural optimization suggests that a displacive-type transformation from B- to A-type sesquioxides structure metastably occurs under pressure at room temperature. The calculated density of states indicates that the transition to the Gd2S3 structure causes a significant decrease in the band gap. The Gd2S3 phase was also found to be partially recovered at ambient pressure. We briefly discuss the quenchability of the Gd2S3 structure in sesquioxides on the basis of the enthalpy differences between the ambient phase and the recovered products.
  • Yusuke Usui, Jun Tsuchiya, Taku Tsuchiya
    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 115 2010年03月 [査読有り]
     研究論文(学術雑誌) 
    Elastic, vibrational and thermodynamic properties of MgGeO3 perovskite (Pv) and postperovskite (PPv) were calculated based on the density functional first principles methods. We found that the calculated properties of MgGeO3 are quite similar to those of MgSiO3 in particular for anomalously large c(66) and small c(55) of PPv, but not fully comparable in particular for the velocity contrasts across the phase change, which are all negative in compressional, shear and bulk velocities at the transition pressure unlike the typical features of the D '' seismic discontinuity. MgGeO3 PPv has larger elastic anisotropy than MgSiO3, but their style is quite similar. Significant orientational preference is needed for PPv polycrystalline aggregate to reproduce seismic shear wave polarization anisotropy observed in D '' except for a case with the c direction aligned vertically. Lattice dynamics calculations indicate that the both phases are vibrationally stable under high pressure, and quasi-harmonic thermodynamics provides the Clapeyron slope of PPv phase boundary of similar to+7.8 MPa/K, which is quite comparable to that reported for MgSiO3. While the calculated Raman frequencies are in excellent agreement with experimental values in Pv, those are found less consistent in PPv.
  • Ishikawa, T., Nagara, H., Suzuki, N., Tsuchiya, J., Tsuchiya, T.
    Journal of Physics: Conference Series 215 1 012105  2010年 研究論文(学術雑誌)
  • Ishikawa, T., Nagara, H., Suzuki, N., Tsuchiya, T., Tsuchiya, J.
    Physical Review B - Condensed Matter and Materials Physics 81 9 092104  2010年 研究論文(学術雑誌)
  • 日本高圧力学会高圧力の科学と技術 20 3 210 - 220 2010年
  • Usui, Y., Tsuchiya, J., Tsuchiya, T.
    Journal of Geophysical Research: Solid Earth 115 3 B03201  2010年 研究論文(学術雑誌)
  • Kenji Kawai, Taku Tsuchiya
    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 106 52 22119 - 22123 2009年12月 研究論文(学術雑誌) 
    The internal structure of the core-mantle boundary (CMB) region of the Earth plays a crucial role in controlling the dynamics and evolution of our planet. We have developed a comprehensive model based on the radial variations of shear velocity in the D '' layer (the base of the lower mantle) and the high-P, T elastic properties of major candidate minerals, including the effects of post-perovskite phase changes. This modeling shows a temperature profile in the lowermost mantle with a CMB temperature of 3,800 +/- 200 K, which suggests that lateral temperature variations of 200-300 K can explain much of the large velocity heterogeneity observed in D ''. A single-crossing phase transition model was found to be more favorable in reproducing the observed seismic wave velocity structure than a double-crossing phase transition model.
  • Manabu Yokoo, Nobuaki Kawai, Kazutaka G. Nakamura, Ken-Ichi Kondo, Yoshinori Tange, Taku Tsuchiya
    Physical Review B - Condensed Matter and Materials Physics 80 10 104114  2009年09月 研究論文(学術雑誌) 
    Equation of state of gold (Au) is revised using the remeasured shock compression data at pressures up to 580 GPa with including the electronic free-energy contribution. The model, even though determined only using pressure-scale-free data, can reproduce not only the shock compression data but also the zero-pressure thermodynamic properties with remarkable accuracy. Previous models for the EOS of copper, silver, and MgO that were constructed using as a basis old shock compression data are found to underestimate the pressure seriously (up to ∼12% at 200 GPa and 300 K). Moreover, we redetermine the EOS model of platinum (Pt) through the same procedure. The determined models of Au and Pt are found mutually highly consistent, which provide quite comparable pressure values in extensive P, T range. These are expected to be more reliable primary pressure standards than previous models. © 2009 The American Physical Society.
  • Manabu Yokoo, Nobuaki Kawai, Kazutaka G. Nakamura, Ken-ichi Kondo, Yoshinori Tange, Taku Tsuchiya
    PHYSICAL REVIEW B 80 10 2009年09月 [査読有り]
     研究論文(学術雑誌) 
    Equation of state of gold (Au) is revised using the remeasured shock compression data at pressures up to 580 GPa with including the electronic free-energy contribution. The model, even though determined only using pressure-scale-free data, can reproduce not only the shock compression data but also the zero-pressure thermodynamic properties with remarkable accuracy. Previous models for the EOS of copper, silver, and MgO that were constructed using as a basis old shock compression data are found to underestimate the pressure seriously (up to similar to 12% at 200 GPa and 300 K). Moreover, we redetermine the EOS model of platinum (Pt) through the same procedure. The determined models of Au and Pt are found mutually highly consistent, which provide quite comparable pressure values in extensive P, T range. These are expected to be more reliable primary pressure standards than previous models.
  • Hitoshl Yusa, Taku Tsuchiya, Nagayoshi Sata, Yasuo Ohishi
    INORGANIC CHEMISTRY 48 16 7537 - 7543 2009年08月 研究論文(学術雑誌) 
    In situ X-ray diffraction experiments using a laser-heated diamond anvil cell revealed a novel dense phase with the Gd2S3 structure stabilizing in Sc2O3 at pressures over 19 GPa. Although no phase transformation was induced during room-temperature compression up to 31 GPa, the C rare earth sesquioxide structure transformed into the B rare earth sesquioxicle structure at 10 GPa after laser annealing and subsequently into the Gd2S3 structure at 19 GPa. Neither the A rare earth sesquioxicle structure nor the U2S3 structure was found in Sc2O3. Static density functional lattice energy calculations demonstrated that the C structure prefers Gd2S3 over U2S3 as the post phase. Sc2O3 is the second sesquioxicle, after In2O3, to crystallize into a Gd2S3 structure at high pressures and high temperatures.
  • Taku Tsuchiya, Mika Fujibuchi
    PHYSICS OF THE EARTH AND PLANETARY INTERIORS 174 1-4 212 - 219 2009年05月 研究論文(学術雑誌) 
    We investigate the effects of silicon incorporation on the structural stability and elasticity of iron at the Earth's inner core pressures by means of the density functional calculation method in order to clarify the acceptability of silicon to the possible light elements dissolving in the inner core. Calculations show that (1) silicon incorporation enhances the bcc stability field as experimental understandings but hcp phase is the most stable at the inner core pressures even in Fe0.875Si0.125, (2) silicon less affects to the elasticity of bcc iron but decreases shear moduli of hcp and fcc phases, (3) it does not drastically change the elastic wave velocities of iron due to the cancellation of associated changes in density and elastic moduli, (4) both P and S wave velocities for each phase and compound linearly depend on the density. and (5) fcc phase is more elastically anisotropic than hcp phase and the anisotropy is enhanced by silicon. We apply two different high-temperature corrections to the wave velocities. Inner core P-wave velocity is well reproduced in the both models, whereas the calculated S-wave velocities significantly depend on the temperature correction. Small effects of silicon on the density-velocity relations are found in both models. (C) 2009 Elsevier B.V. All rights reserved.
  • Yoshinori Tange, Yu Nishihara, Taku Tsuchiya
    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 114 2009年03月 [査読有り]
     研究論文(学術雑誌) 
    In order to determine an accurate and reliable high-pressure and high-temperature equation of state (EOS) of MgO, unified analyses were carried out for various pressure-scale-free experimental data sets measured at 1 atm to 196 GPa and 300-3700 K, which are zero-pressure thermal expansion data, zero-pressure and high-temperature adiabatic bulk modulus (K-S) data, room temperature and high-pressure KS data, and shock compression data. After testing several EOS models based on the Mie-Gruneisen-Debye description for the thermal pressures with the Vinet and the third-order Birch-Murnaghan equations for the 300-K isothermal compression, we determined the K'(T0) and gamma(V) using a new functional form gamma = gamma(0){1 + a[(V/V-0)(b)-1]} to express the volume dependence of the Gruneisen parameter. Through least squares analyses with prerequisite zero-pressure and room temperature properties of V-0, K-S0, alpha(0), and C-P0, we simultaneously optimized a set of parameters of K'(T0), gamma(0), alpha, and b required to represent the P-V-T EOS. Determined new EOS models of MgO successfully reproduced all the analyzed P-V-T-K-S data up to 196 GPa and 3700 K within the uncertainties, and the total residuals between calculated and observed pressures were found to be 0.8 GPa in root mean squares. These EOS models, even though very simple, are able to reproduce available data quite accurately in the wide pressure-temperature range and completely independent from other pressure scales. We propose these models for primary pressure calibration standards applicable to quantitative high-pressure and high-temperature experiments.
  • Kawai, K., Tsuchiya, T., Tsuchiya, J., Maruyama, S.
    Gondwana Research 16 3-4 581 - 586 2009年 研究論文(学術雑誌)
  • TSUCHIYA Jun, TSUCHIYA Taku
    ElsevierPhysics of Earth and Planetary Interiors 174 1-4 122 - 127 2009年 研究論文(学術雑誌)
  • TANGE Yoshinori, NISHIHARA Yu, TSUCHIYA Taku
    American Geophysical UnionJournal of Geophysical Research 114 B3 B03208  2009年
  • Tsuchiya, J., Tsuchiya, T.
    Journal of Geophysical Research: Solid Earth 114 2 B02206  2009年 研究論文(学術雑誌)
  • Jung-Fu Lin, Taku Tsuchiya
    PHYSICS OF THE EARTH AND PLANETARY INTERIORS 170 3-4 248 - 259 2008年11月 研究論文(学術雑誌) 
    Electronic spin-pairing transitions of iron and associated effects on the physical properties of host phases have been reported in lower-mantle minerals including ferropericlase, silicate perovskite, and possibly in post-perovskite at lower-mantle pressures. Here we evaluate current understanding of the spin and valence states of iron in the lower-mantle phases, emphasizing the effects of the spin transitions on the density, sound velocities, chemical behavior, and transport properties of the lower-mantle phases. The spin transition of iron in ferropericlase occurs at approximately 50 GPa and room temperature but turns into a wide spin crossover under lower-mantle temperatures. Current experimental results indicate a continuous nature of the spin crossover in silicate perovskite at high pressures, but Which valence state of iron undergoes the spin crossover and what is its associated crystallographic site remain uncertain. The spin transition of iron results in enhanced density, incompressibility, and sound velocities, and reduced radiative thermal conductivity and electrical conductivity in the low-spin ferropericlase, which should be considered in future geophysical and geodynamic modeling of the Earth's lower mantle. In addition, a reduction in sound velocities within the spin transition is recently reported. Our evaluation of the experimental and theoretical pressure-volume results shows that the spin crossover of iron results in a density increase of 2-4% in ferropericlase containing 17-20% FeO. Here we have modeled the density and bulk modulus profiles of ferropericlase across the spin crossover under lower-mantle pressure-temperature conditions and shown how the ratio of the spin states of iron affects our understanding of the state of the Earth's lower mantle. (C) 2008 Elsevier B.V. All rights reserved.
  • Hitoshi Yusa, Taku Tsuchiya, Nagayoshi Sata, Yasuo Ohishi
    Physical Review B - Condensed Matter and Materials Physics 77 6 2008年02月 [査読有り]
     研究論文(学術雑誌) 
    High-pressure transitions of Ga2 O3 and In2 O3 were examined by using a laser-heated diamond-anvil cell combined with in situ x-ray diffractometry at pressures up to 108 GPa and 20 GPa, respectively. To predict the transition pressure to high-pressure phases, first principles static lattice energy calculations based on the density functional theory were also performed. Rh2 O3 (II) phases were confirmed as post corundum phases for both Ga2 O3 and In2 O3 at about 37 GPa and 7 GPa, respectively. The transition pressures determined by high-pressure experiments are almost consistent with those by theoretical computations. In regard to the present sesquioxides, a link of transition from corundum to perovskite was not confirmed. The Rh2 O3 (II) phases converted to corundum phases under decompression at room temperature. The bulk modulus of Rh2 O3 (II) phase in Ga2 O3 and In2 O3 were determined as 271±10 GPa and 169±4 GPa with their pressure derivatives fixed at 4, respectively. © 2008 The American Physical Society.
  • TSUCHIYA Jun, TSUCHIYA Taku
    The National Academy of Sciences of the United States of AmericaProceedings of the National Academy of Sciences of the United States of America 105 49 19160 - 19164 2008年 研究論文(学術雑誌)
  • Yusa, H., Tsuchiya, T., Tsuchiya, J., Sata, N., Ohishi, Y.
    American Physical SocietyPhysical Review B 78 9 092107  2008年 研究論文(学術雑誌)
  • Tsuchiya, J., Tsuchiya, T.
    Physics of the Earth and Planetary Interiors 170 3-4 215 - 220 2008年 研究論文(学術雑誌)
  • Tsuchiya, J., Tsuchiya, T., Sano, A., Ohtani, E.
    Journal of Mineralogical and Petrological Sciences 103 2 116 - 120 2008年 研究論文(学術雑誌)
  • Rh2O3(II)-type structures in Ga2O3 and In2O3 under high pressure
    American Physical SocietyPhysical Review B 77 064107  2008年
  • Tsuchiya, J., Tsuchiya, T., Wentzcovitch, R.M.
    Mineralogical Society of AmericaAmerican Mineralogist 93 2-3 477 - 482 2008年 研究論文(学術雑誌)
  • Yonggang G. Yu, Renata M. Wentzcovitch, Taku Tsuchiya, Koichiro Umemoto, Donald J. Weidner
    GEOPHYSICAL RESEARCH LETTERS 34 10 L10306 doi:10.1029/2007GL029462  2007年05月 研究論文(学術雑誌) 
    We have investigated the dissociation of iron free ringwoodite, Mg2SiO4 gamma-spinel, into MgO periclase and MgSiO3 perovskite using quasi-harmonic free energy computations within the local density approximation (LDA) and generalized gradient approximation (GGA). The transition pressure, P-tr, obtained from GGA is higher and in much better agreement with experimental measurements than its LDA counterpart. This can be rationalized by close inspection of GGA and LDA functional forms. The Clapeyron slope obtained from this calculation is - 2.9 - - 2.6 MPa/K. Surprisingly, we find a small decrease in bulk sound velocity across this transition. Our results are consistent with 64 +/- 12% ringwoodite volume fraction at the bottom of the transition zone.
  • Wentzcovitch, R.M., Umemoto, K., Tsuchiya, T., Tsuchiya, J.
    Geophysical Monograph Series 174 2007年 [査読有り]
     研究論文(学術雑誌)
  • Taku Tsuchiya, Jun Tsuchiya, Renata M. Wentzcovitch
    Superplumes: Beyond Plate Tectonics 83 - 103 2007年 [査読有り]
     研究論文(学術雑誌) 
    A high-pressure phase transition in iron free MgSiO3 perovskite, the most abundant Earth forming mineral phase, was discovered and reported in 2003-2004. Here, we summarize our theoretical and computational studies on this phase transition and on the physical properties of the newly found post-perovskite phase. The theoretical approach is based on density functional theory and on the plane-wave pseudopotential method. We focus here on the structural, elastic, vibrational, and thermodynamic properties of the post-perovskite phase. The predicted Clapeyron slope of this transition and several elastic properties of the highpressure phase strongly suggest that this new phase is an important candidate for a primary constituent in D″. © 2007 Springer.
  • Tsuchiya, T., Tsuchiya, J.
    Physical Review B - Condensed Matter and Materials Physics 76 14 144119  2007年 研究論文(学術雑誌)
  • Tsuchiya, T., Yusa, H., Tsuchiya, J.
    Physical Review B - Condensed Matter and Materials Physics 76 17 174108  2007年 研究論文(学術雑誌)
  • Tsuchiya, T., Tsuchiya, J.
    Physical Review B - Condensed Matter and Materials Physics 76 9 092105  2007年 研究論文(学術雑誌)
  • T Tsuchiya, RM Wentzcovitch, CRS da Silva, S de Gironcoli
    PHYSICAL REVIEW LETTERS 96 19 198501  2006年05月 研究論文(学術雑誌) 
    Iron in the major lower mantle (LM) minerals undergoes a high spin (HS) to low spin (LS) transition at relevant pressures (23-135 GPa). Previous failures of standard first principles approaches to describe this phenomenon have hindered its investigation and the clarification of important consequences. Using a rotationally invariant formulation of LDA+U we report a successful study of this transition in low solute concentration magnesiowustite, (Mg1-xFex)O, (x < 0.2), the second most abundant LM phase. We show that the HS-LS transition goes through an insulating (semiconducting) intermediate mixed spins (MS) state without discontinuous changes in properties, as seen experimentally. We show that the HS state crosses over smoothly to the LS state passing through an insulating MS state where properties change continuously, as seen experimentally.
  • Tsuchiya, T., Tsuchiya, J.
    American Mineralogist 91 11-12 1879 - 1887 2006年 研究論文(学術雑誌)
  • Tsuchiya, T., Wentzcovitch, R.M., Da Silva, C.R.S., De Gironcoli, S., Tsuchiya, J.
    Physica Status Solidi (B) Basic Research 243 9 2111 - 2116 2006年 研究論文(学術雑誌)
  • Tsuchiya, T., Tsuchiya, J.
    Geophysical Research Letters 33 12 L12S04 doi:10.1029/2006GL025706  2006年 研究論文(学術雑誌)
  • Wentzcovitch, R.M., Tsuchiya, T., Tsuchiya, J.
    Proceedings of the National Academy of Sciences of the United States of America 103 3 543 - 546 2006年 研究論文(学術雑誌)
  • MgSiO3 post-perovskite at D" conditions
    ElsevierGeochimica et Cosmochimica Acta 69 A508  2005年
  • Lay, T., Heinz, D., Ishii, M., Shim, S.-H., Tsuchiya, J., Tsuchiya, T., Wentzcovitch, R., Yuen, D.
    Eos 86 1 1 - 3 2005年 研究論文(学術雑誌)
  • Tsuchiya, J., Tsuchiya, T., Tsuneyuki, S.
    American Mineralogist 90 1 44 - 49 2005年 研究論文(学術雑誌)
  • Tsuchiya, J., Tsuchiya, T., Wentzcovitch, R.M.
    Journal of Geophysical Research: Solid Earth 110 2 B02204  2005年 研究論文(学術雑誌)
  • Tsuchiya, J., Tsuchiya, T., Wentzcovitch, R.M.
    Physical Review B - Condensed Matter and Materials Physics 72 2 020103(R)  2005年 研究論文(学術雑誌)
  • Hiroshi Sakuma, Taku Tsuchiya, Katsuyuki Kawamura, Kenshiro Otsuki
    Molecular Simulation 30 13-15 861 - 871 2004年11月 研究論文(国際会議プロシーディングス) 
    The structural and dynamic properties of water between brucite (0001), talc (001), and halite (100) surfaces have been calculated by classical molecular dynamics (MD) simulations at ambient conditions. The interaction potential models between water and the minerals have been developed by the energy curves obtained from the ab initio electronic state calculations. Orientational anisotropy of water molecules is almost limited in the vicinity of all the surfaces. The significant different properties of water between the surfaces are observed in the density profiles and self-diffusion coefficients. The density profile of water between talc surfaces is flat and the density is equivalent to the bulk one, while those of water between brucite and halite surfaces strongly oscillate with the distance from the surfaces. The self-diffusion coefficients parallel to the surfaces are enhanced in the vicinity of brucite and talc surfaces, and reduced on halite surface compared with that in bulk.
  • K Harafuji, T Tsuchiya, K Kawamura
    JOURNAL OF APPLIED PHYSICS 96 5 2501 - 2512 2004年09月 研究論文(学術雑誌) 
    A two-phase molecular dynamics simulation of coexisting solid and liquid has been carried out to investigate the melting point of wurtzite-type GaN crystals. The melting point is determined by examining the movement of the interface between the solid and liquid during the simulation. The potential is a two-body interatomic one composed of the long-range Coulomb interaction, the Gilbert-type short-range repulsion, the covalent bonding and covalent repulsion of the modified Morse type, and the van der Waals interaction. The melting point and the interface morphology depend on the crystallization direction. The melting point T-m (K) increases with pressure P (GPa), but there appears a discontinuity in the vicinity of 8-9 GPa. This is due to the solid-electrolyte-like behavior of Ga atoms with a partial charge in the high-pressure region. The discontinuity has not yet been confirmed by experiment. The least-squares fitted result is T-m=2538+177P-4.62P(2) at pressures lower than 8 GPa and T-m=2825+210P-5P(2) at pressures higher than 9 GPa. The Clausius-Clapeyron relation is confirmed using calculated thermodynamic data. (C) 2004 American Institute of Physics.
  • K Harafuji, T Tsuchiya, K Kawamura
    JOURNAL OF APPLIED PHYSICS 96 5 2513 - 2524 2004年09月 研究論文(学術雑誌) 
    Microscopic dislocation structures in wurtzite-type GaN crystal have been studied by the use of molecular dynamics simulation. Parameters for a two-body interatomic potential are determined by the Hartree-Fock ab initio method. A dislocation is generated by the coalescence of the facing planes of a semi-infinite trench structure in the crystal. Six types of trench structures with different depth-directions and extension-directions are examined. Temperatures of 1000 and 1500 K are considered. A core structure with an eightfold ring has been confirmed for edge dislocations along the c axis, though there appear a few atoms that are shifted from the ring core structure. The ring core structure is consistent with reported theoretical expectations and experimental observations. A tenfold ring core structure is also observed for edge dislocations along the c axis. A screw dislocation is generated by an attracting force between gallium and nitrogen atoms across the trench space when the attracting force has a large component parallel to the trench extension direction. (C) 2004 American Institute of Physics.
  • M Murakami, K Hirose, S Ono, T Tsuchiya, M Isshiki, T Watanuki
    PHYSICS OF THE EARTH AND PLANETARY INTERIORS 146 1-2 273 - 282 2004年08月 研究論文(学術雑誌) 
    We investigated the phase transitions of FeO at high pressure and high temperature up to 87 GPa and 1730 K by in situ synchrotron X-ray diffraction measurements in a laser-heated diamond anvil cell (DAC). The results demonstrated that the NaCl-type (B1) structure of FeO undergoes transition to the NiAs-type (B8) structure above 70 GPa at 1600 K. The density increase across this transition is about 2%. Present B1-B8 transition pressure is consistent with the previous shock-induced transition pressure. The relative intensities of diffraction peaks of the B8 phase may suggest a polytype normal/inverse NiAs structure, which has a metallic nature that could promote the oxygen incorporation into the iron-rich core. Transition to the metallic B8 phase above 70 GPa is also consistent with the earlier electrical resistance measurements. The hexagonal close-packed (hcp) epsilon-phase of Fe coexisted with FeO both at room temperature and high temperatures above 44-87 GPa. (C) 2004 Elsevier B.V. All rights reserved.
  • K Harafuji, T Tsuchiya, K Kawamura
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 43 2 522 - 531 2004年02月 研究論文(学術雑誌) 
    The behaviors of Ga and N vacancies (Schottky defects, Frenkel defects), lattice-site and interstitial Mg atoms, and interstitial H atoms are studied in the wurtzite-type GaN crystal by molecular dynamic simulation. Parameters for a two-body interatomic potential are determined by the Hartree-Fock ab initio method. When there are Schottky defects, Ga and N vacancies are often paired, and the paired vacancies repeatedly form and disappear during the simulation. When there are Frenkel defects, interstitial Ga or N atoms become lattice-site ones by the substitutional-interstitial mechanism. The lattice-site Mg atom shows a very stable state, stays there for a long period and undergoes thermal vibration. The interstitial Mg atom is in a semistable state at the cage center of a hexagonal crystal structure. The Mg atom undergoes thermal vibration there, then hops from one cage center to an adjacent one. The diffusivity of interstitial Mg atoms on the (0001) plane is predominant compared with the diffusivity along the [0001] direction.
  • 日本高圧力学会高圧力の科学と技術 14 61 - 67 2004年
  • 土屋 卓久
    日本高圧力学会高圧力の科学と技術 14 2 173 - 183 2004年
  • Tsuchiya, T., Caracas, R., Tsuchiya, J.
    Geophysical Research Letters 31 11 L11610 doi:10.1029/2004GL019649  2004年 研究論文(学術雑誌)
  • Tsuchiya, T., Tsuchiya, J., Umemoto, K., Wentzcovitch, R.M.
    Earth and Planetary Science Letters 224 3-4 241 - 248 2004年 研究論文(学術雑誌)
  • Tsuchiya, T., Tsuchiya, J., Umemoto, K., Wentzcovitch, R.M.
    Geophysical Research Letters 31 14 L14603 doi:10.1029/2004GL020278  2004年 研究論文(学術雑誌)
  • K Shiraki, T Tsuchiya, S Ono
    ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS 59 701 - 708 2003年12月 研究論文(学術雑誌) 
    Recently, there has been substantial interest in the new high-pressure polymorphs of GeO2 synthesized in the laboratory. Previous investigators reported the synthesis of 'CaCl2-type', 'alpha-PbO2-type' and 'pyrite-type (modfied-fluorite-type)' GeO2 at pressures of 30 - 130 GPa in laser-heated diamond anvil cells. In order to provide definitive information about the new high-pressure polymorphs, we performed Rietveld refinements of the structures. The structure refinements confirm that two of these high-pressure phases do have the alpha-PbO2-type and pyrite-type (modified-fluorite-type) structures.
  • T Tsuchiya
    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH 108 B10 2462 doi:10.1029/2003JB002446  2003年10月 研究論文(学術雑誌) 
    [1] The P-V-T equation of state (EOS) of gold is the most frequently used pressure calibration standard in high-P-T in situ experiments. Empirically proposed EOS models, however, severely scatter under high-P-T conditions, which is a serious problem for studies of the deep Earth. In this study, the EOS of gold is predicted using a first-principles electronic structure calculation method without any empirical parameters. The calculated thermoelastic properties of gold compare favorably to experimental data at ambient conditions so that B-T0 and B'(T0) are 166.7 GPa and 6.12, respectively. Up to V/V-a = 0.7, the calculated Gruneisen parameter of gold depends on volume according to the function gamma/gamma(a) = (V/V-a)(zeta) with gamma(a) of 3.16 and zeta of 2.15. On the basis of these data, the validity of previous EOS models is discussed. It is found that the present ab initio EOS provides a 1.3 GPa higher pressure than Anderson's scale at 23 GPa and 1800 K and largely reduces the discrepancy observed between conditions at the transition of Mg2SiO4 and the 660-km seismic discontinuity. However, a discrepancy of about 0.7 GPa still remains between the 660-km discontinuity and the postspinel transition.
  • S Ono, T Tsuchiya, K Hirose, Y Ohishi
    American Physical SocietyPhysical Review B 68 13 134108  2003年10月 研究論文(学術雑誌) 
    Observations of the phase transition between the CaCl2-type (Pnnm) and alpha-PbO2-type (Pbcn) structures of germanium dioxide (GeO2) were carried out using quench and in situ x-ray diffraction methods in a laser-heated diamond anvil cell (LHDAC). First-principle theoretical simulations were also performed to complement the experimental results. The experiments showed that the transition had a positive dP/dT dependence. The phase boundary between the CaCl2-type and alpha-PbO2-type structures in the temperature range 1500-2400 K was determined to be P (GPa)=(53+/-3)+(0.011+/-0.005)(T-1800) (K) based on the equation of state of platinum and the ruby scale. The positive slope of the transition is consistent with the known phase boundary between the CaCl2-type and alpha-PbO2-type structures of tin dioxide (SnO2) as germanium dioxide analog and theoretical simulation results. However, our results do not agree with the slope of the phase boundary of silica (SiO2), which has been reported to have a negative slope.
  • S Ono, T Tsuchiya, K Hirose, Y Ohishi
    PHYSICAL REVIEW B 68 1 014103  2003年07月 研究論文(学術雑誌) 
    Structural phase transitions of germanium dioxide (GeO2) have been investigated at pressures up to 120 GPa, which was heated to a temperature above 2000 K, using a laser-heated diamond anvil cell technique. A phase transition between CaCl2-type and alpha-PbO2-type phases was observed at about 50 GPa. At pressures higher than 90 GPa, we also observed the occurrence of a new high-pressure phase of pyrite-type (modified-fluorite type) structure (Pa (3) over bar) that is denser than other known GeO2 phases. Our results were consistent with the high-pressure transition sequence of tin dioxide (SnO2) as analog of GeO2. The new structure of the GeO2 high-pressure phase may be that of high-pressure silica (SiO2) phase predicted by the theoretical investigations.
  • K. Harafuji, T. Tsuchiya, K. Kawamura
    Physica Status Solidi C: Conferences 7 2420 - 2423 2003年 [査読有り]
     研究論文(国際会議プロシーディングス) 
    A two-phase molecular dynamic simulation of coexisting solid and liquid has been made for a wurtzite-type GaN crystal. The melting point is determined by examining the movement of the interface between solid and liquid during the calculation. The pressure dependence of the melting point is systematically obtained for the first time. The melting point Tm increases linearly with pressure P as Tm(K) = 2513 + 186 × P(GPa). © 2003 WILEY-VCH Verlag GmbH & Co. KGaA.
  • Shigeaki Ono, Taku Tsuchiya, Kei Hirose, Yasuo Ohishi
    Physical Review B - Condensed Matter and Materials Physics 68 13 2003年 [査読有り]
     研究論文(学術雑誌) 
    Observations of the phase transition between the CaCl2-type (Pnnm) and α-PbO2-type (Pbcn) structures of germanium dioxide (GeO2) were carried out using quench and in situ x-ray diffraction methods in a laser-heated diamond anvil cell (LHDAC). First-principle theoretical simulations were also performed to complement the experimental results. The experiments showed that the transition had a positive dP/dT dependence. The phase boundary between the CaCl2-type and α-PbO2-type structures in the temperature range 1500–2400 K was determined to be P (GPa)=(53±3)+(0.011±0.005)(T-1800) (K) based on the equation of state of platinum and the ruby scale. The positive slope of the transition is consistent with the known phase boundary between the CaCl2-type and α-PbO2-type structures of tin dioxide (SnO2) as germanium dioxide analog and theoretical simulation results. However, our results do not agree with the slope of the phase boundary of silica (SiO2), which has been reported to have a negative slope. © 2003 The American Physical Society.
  • Shigeaki Ono, Taku Tsuchiya, Kei Hirose, Yasuo Ohishi
    Physical Review B - Condensed Matter and Materials Physics 68 1 2003年 [査読有り]
     研究論文(学術雑誌) 
    Structural phase transitions of germanium dioxide (GeO2) have been investigated at pressures up to 120 GPa, which was heated to a temperature above 2000 K, using a laser-heated diamond anvil cell technique. A phase transition between CaCl2-type and α-PbO2-type phases was observed at about 50 GPa. At pressures higher than 90 GPa, we also observed the occurrence of a new high-pressure phase of pyrite-type (modified-fluorite type) structure (Pa3−) that is denser than other known GeO2 phases. Our results were consistent with the high-pressure transition sequence of tin dioxide (SnO2) as analog of GeO2. The new structure of the GeO2 high-pressure phase may be that of high-pressure silica (SiO2) phase predicted by the theoretical investigations. © 2003 The American Physical Society.
  • ブルーサイト(Mg(OH)2)-水系の分子シミュレーション
    分子シミュレーション研究会分子シミュレーション研究会Newsletter 21 2003年
  • 高圧下における含水鉱物の第一原理計算による研究
    分子シミュレーション研究会分子シミュレーション研究会Newsletter 21 2003年
  • Precise measurement of equation-of-state and elastic properties for GaN up to 16 GPa
    PFPF Activity Report Highlight 27 - 28 2003年
  • SAKUMA H, TSUCHIYA T, KAWAMURA K, OTSUKI K
    ElsevierSurface Science 536 1/3 L396 - L402 2003年
  • K Harafuji, T Tsuchiya, K Kawamura
    5TH INTERNATIONAL CONFERENCE ON NITRIDE SEMICONDUCTORS (ICNS-5), PROCEEDINGS 0 7 2420 - 2423 2003年 研究論文(国際会議プロシーディングス) 
    A two-phase molecular dynamic simulation of coexisting solid and liquid has been made for a wurtzite-type GaN crystal. The melting point is determined by examining the movement of the interface between solid and liquid during the calculation. The pressure dependence of the melting point is systematically obtained for the first time. The melting point To, increases linearly with pressure P as T-m(K) = 2513 + 186 x P(GPa). (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • K Harafuji, T Tsuchiya, K Kawamura
    5TH INTERNATIONAL CONFERENCE ON NITRIDE SEMICONDUCTORS (ICNS-5), PROCEEDINGS 0 7 2240 - 2243 2003年 研究論文(国際会議プロシーディングス) 
    The behaviors of Ga and N vacancies (Schottky defects, Frenkel defects), lattice-site and interstitial Mg atoms, and interstitial H atoms have been studied in the wurtzite-type GaN crystal by molecular dynamic simulation. The diffusivity of interstitial Mg atoms on the (0001) plane is predominant compared with the diffusivity along the [0001] direction. Diffusion coefficients of interstitial Mg atoms are composed of two Arrhenius formula for temperatures from 850 K to 2000 K. The one reflects the high-possibility occurrence of jumping movements among cage centers of hexagonal crystal structure for higher temperature. The other reflects the thermal vibration at the cage center for lower temperature. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  • Taku Tsuchiya, Katsuyuki Kawamura
    Physical Review B - Condensed Matter and Materials Physics 66 9 941151 - 941155 2002年09月 [査読有り]
     研究論文(学術雑誌) 
    Electronic thermal pressures (ETP's) of metal Au and Pt are predicted by first-principles electronic structure calculations based on the density functional theory in order to refine their thermal equations of state (EOS) which are frequently used as pressure scales in in situ high-pressure and high-temperature experiment. We find a large difference in the magnitude of ETP's for Au and Pt, which can be attributed to the different positions of the Fermi level. The ETP for Au is considerably smaller than it for Pt. The latter reaches 0.85 GPa at 2000 K, whereas the former is only 0.05 GPa at the same temperature. We also find a different temperature dependence of the ETP's of Au and Pt under high temperature, which arises from the different manner of thermal excitation. It is illustrated that the corrections of the ETP for known EOS of Au and Pt becomes substantially important with increasing temperature, and the ETP can perfectly compensate for the measured discrepancy of pressure values determined by previous EOS of Au and Pt.
  • T Tsuchiya, K Kawamura
    JOURNAL OF CHEMICAL PHYSICS 117 12 5859 - 5865 2002年09月 研究論文(学術雑誌) 
    Elastic properties and their pressure dependence of rare gas solids (RGSs) Ne, Ar, Kr, and Xe are calculated using the ab initio full-potential linear muffin-tin-orbital method to study their systematics. Though the local density approximation (LDA) underestimates volume of these substances, especially Ne, equations of state and elastic constants are well reproduced in the entire pressure range up to a megabar. The Cauchy deviation, the Zener anisotropy ratio, and the normalized elastic constant are investigated as a function of pressure. It is found that many-body contribution to the interatomic force surprisingly increases with increasing pressure even in all RGSs and it is larger in the heavier element. The elastic anisotropy of all four RGSs gradually decreases with increasing pressure. The normalized elastic constants c(11)' and c(12)' largely deviate from the ideal values, and c(ij)''s are remarkably insensitive to pressure over 10 GPa. Moreover, no elastic instability appears under high pressure in all RGSs. Consequently, LDA is sufficiently valid even for RGS since the van der Waals interaction becomes minor with increasing pressure. These trends of high-pressure elastic property are quite different from those of ionic solid and metal. (C) 2002 American Institute of Physics.
  • T Tsuchiya, K Kawamura
    PHYSICAL REVIEW B 66 9 094115  2002年09月 研究論文(学術雑誌) 
    Electronic thermal pressures (ETP's) of metal Au and Pt are predicted by first-principles electronic structure calculations based on the density functional theory in order to refine their thermal equations of state (EOS) which are frequently used as pressure scales in in situ high-pressure and high-temperature experiment. We find a large difference in the magnitude of ETP's for Au and Pt, which can be attributed to the different positions of the Fermi level. The ETP for Au is considerably smaller than it for Pt. The latter reaches 0.85 GPa at 2000 K, whereas the former is only 0.05 GPa at the same temperature. We also find a different temperature dependence of the ETP's of Au and Pt under high temperature, which arises from the different manner of thermal excitation. It is illustrated that the corrections of the ETP for known EOS of Au and Pt becomes substantially important with increasing temperature, and the ETP can perfectly compensate for the measured discrepancy of pressure values determined by previous EOS of Au and Pt.
  • T Tsuchiya, K Kawamura
    JOURNAL OF CHEMICAL PHYSICS 116 5 2121 - 2124 2002年02月 研究論文(学術雑誌) 
    Pressure dependence of elastic properties of crystalline Au is calculated based on the first-principles method within the local density approximation for the first time. The calculated equation of state agrees quite well with the results of previous high-pressure experiments. From the present study we find several unique features of the elasticity of Au as follows. (1) The calculated dependence of elastic constants on pressure supports the experiments demonstrating relatively smaller pressure derivatives. (2) The small tetragonal shear constant c(s)=(c(11)-c(12))/2 in Au is remarkably insensitive to pressure, but elastic instability does not appear in the calculated pressure range. This feature is inferred to result from a small covalent nature in the chemical bonding in Au. (3) The elastic anisotropy increases with pressure. The normalized elastic constants considerably deviate from the ideal values and keep almost constant in wide volume variations. (C) 2002 American Institute of Physics.
  • Taku Tsuchiya, Katsuyuki Kawamura
    Physical Review B - Condensed Matter and Materials Physics 66 9 1 - 5 2002年 [査読有り]
     研究論文(学術雑誌) 
    Electronic thermal pressures (ETP’s) of metal Au and Pt are predicted by first-principles electronic structure calculations based on the density functional theory in order to refine their thermal equations of state (EOS) which are frequently used as pressure scales in in situ high-pressure and high-temperature experiment. We find a large difference in the magnitude of ETP’s for Au and Pt, which can be attributed to the different positions of the Fermi level. The ETP for Au is considerably smaller than it for Pt. The latter reaches 0.85 GPa at 2000 K, whereas the former is only 0.05 GPa at the same temperature. We also find a different temperature dependence of the ETP’s of Au and Pt under high temperature, which arises from the different manner of thermal excitation. It is illustrated that the corrections of the ETP for known EOS of Au and Pt becomes substantially important with increasing temperature, and the ETP can perfectly compensate for the measured discrepancy of pressure values determined by previous EOS of Au and Pt. © 2002 The American Physical Society.
  • 佐藤 久子, 土屋 卓久, 河村 雄行
    日本粘土学会粘土科学 41 4 190 - 195 2002年
  • T Tsuchiya, K Kawamura, O Ohtaka, H Fukui, T Kikegawa
    SOLID STATE COMMUNICATIONS 121 9-10 555 - 559 2002年 研究論文(学術雑誌) 
    To determine the bulk modulus (B-0) and its pressure derivative (B'(0)) of wurtzite-type GaN, the room temperature pressure (P)-volume (V) equation-of-state (EOS) is precisely measured up to 16 GPa by quasihydrostatic compression experiments with in situ energy-dispersive X-ray diffraction. In the present experiments we especially pay attention to the hydrostaticity of pressure conditions since previous studies implied that it largely affected to B-0 and B-0'. Nonhydrostatic effect is eliminated by enough annealing at each pressure. We find B-0 = 202.4 GPa and B-0' = 4.5 by fitting to the third-order Birch-Murnaghan EOS. Though being different from the earlier experimental results using diamond-anvil cells, these values are quite concordant with recent data from Brillouin spectroscopies and ab initio calculations. Furthermore, we confirm that linear compressibilities (beta) along a and c directions are almost same in GaN as beta(a) = 1.481 X 10(-3) and beta(c) = 1.402 X 10(-3), differing from other wurtzite-type group III nitrides. This corresponds to a small pressure dependence of the axial ratio c/a and the high ideality of the GaN lattice not only at ambient pressure but also under high pressures. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • Tsuchiya, J.M., Tsuchiya, T., Tsuneyuki, S., Yamanaka, T.
    American Geophysical UnionGeophysical Research Letters 29 19 1909 doi:10.1029/2002GL015417  2002年 研究論文(学術雑誌)
  • T Tsuchiya, K Kawamura
    JOURNAL OF CHEMICAL PHYSICS 114 22 10086 - 10093 2001年06月 研究論文(学術雑誌) 
    The elastic properties and their pressure dependence of four B1-type alkaline earth oxides, MgO, CaO, SrO, and BaO, are calculated using the ab initio full-potential linear muffin-tin-orbital (FP-LMTO) generalized gradient approximated (GGA) method to elucidate their systematics. The calculated results agree quite well with the comparable experimental data. The large pressure dependence of c(11) and c(44) of MgO observed over 25 GPa is not predicted as well as the previous local-density approximation (LDA) calculations. It is inferred that the high-pressure measurement of elastic constant is quite sensitive to nonhydrostaticity. The deviation from the Cauchy relation and the elastic anisotropy are investigated. It is found that the interatomic interaction in SrO is nearest to the two-body force and the many-body contribution is largest in MgO. The elastic anisotropy in SrO and BaO are almost the same and only MgO has a large positive anisotropy under low pressure. The normalized elastic constants c(ij)' are introduced for more detail analysis. It is found that while there is no substantial difference in c(11)' and c(12)' of the four oxides, only c(44)' and its pressure dependence vary systematically. The difference in the Cauchy deviation and elastic anisotropy of alkaline earth oxides under pressure is characterized by c(44). (C) 2001 American Institute of Physics.
  • HATTORI T, TSUCHIYA T, NAGAI T, YAMANAKA T
    SpringerPhysics and Chemistry of Minerals 28 6 377 - 387 2001年
  • T Tsuchiya, T Yamanaka, M Matsui
    PHYSICS AND CHEMISTRY OF MINERALS 27 3 149 - 155 2000年02月 研究論文(学術雑誌) 
    We simulated quartz-type GeO2 and investigated its high-pressure transformation using the molecular dynamics (MD) simulation method with a model potential, The calculated results under hydrostatic compression indicated that a pi pressure-induced amorphization of quartz-type GeO2 originated from the mechanical instability of the quartz lattice as, in previous theoretical studies of SiO2. Furthermore, quartz-type GeO2 directly transformed to a rutile-like structure with only subtle displacements of ions under sigma(xy) imposed shear stressed decompression. This is the first reproduction of the quartz-to-rutile transformation. A possible pathway of this transition is proposed in this study.
  • 酸化物鉱物の圧力誘起構造相転移と弾性安定性に関する分子動力学計算
    分子シミュレーション研究会分子シミュレーション研究会Newsletter 10 2000年
  • The bond character of rutile type SiO2, GeO2 and SnO2 investigated by molecular orbital calculation
    J Mimaki, T Tsuchiya, T Yamanaka
    ZEITSCHRIFT FUR KRISTALLOGRAPHIE 215 7 419 - 423 2000年 研究論文(学術雑誌) 
    Molecular orbital calculations using descrete-variational Xa method were carried out in order to investigate the bond nature of SiO2, GeO2 and SnO2. The bond overlap populations and the d-orbital populations of cations were decreased with increasing the atomic number. The deformation density maps of electronic charge show the accumulation of electron in interatomic region which is most dominant in SiO2. The calculated density of states indicates that the bond character of SiO2 is more covalent than that of GeO2 and SnO2. From the excited d-electron partial density of states, it is inferred that the Si excited-3d has some connection with the bond nature of SiO2 covalency.
  • T Hattori, T Matsuda, T Tsuchiya, T Nagai, T Yamanaka
    PHYSICS AND CHEMISTRY OF MINERALS 26 3 212 - 216 1999年02月 研究論文(学術雑誌) 
    In order to confirm the possible existence of FeGeO3 perovskite, we have performed in situ X-ray diffraction measurements of FeGeO3 clinopyroxene at pressures up to 40 GPa at room temperature. The transition of FeGeO3 clinopyroxene into orthorhombic perovskite is observed at about 33GPa. The cell parameters of FeGeO3 perovskite are a=4.93(2) Angstrom, b=5.06(6) Angstrom, c=6.66(3) Angstrom and V=166(3) Angstrom(3) at 40 GPa. On release of pressure, the perovskite phase transformed into lithium niobate structure. The previously reported decomposition process of clinopyroxene into Fe2GeO4 (spinel)+GeO2 (rutile) or FeO (wustite) +GeO2 (rutile) was not observed. This shows that the transition of pyroxene to perovskite is kinetically accessible compared to the decomposition processes un der low-temperature pressurization.
  • GeO2の高圧誘起構造相転移のMD
    海洋出版月刊地球 21 116 - 121 1999年
  • Dynamical observation of the pressure-induced structure change
    KEKKEK Proceedings 14 99 - 102 1999年
  • 土屋 卓久, 山中 高光
    日本鉱物学会鉱物学雑誌 27 3 137 - 145 1998年
  • T Tsuchiya, T Yamanaka, M Matsui
    PHYSICS AND CHEMISTRY OF MINERALS 25 2 94 - 100 1998年01月 研究論文(学術雑誌) 
    A two-body interatomic potential model for GeO2 polymorphs has been determined to simulate the structure change of them by semi-empirical procedure, total lattice energy minimization of GeO2 polymorphs. Based on this potential, two polymorphs of GeO2; alpha-quartz-type and rutile-type, have been reproduced using the molecular dynamics (MD) simulation techniques. Crystal structures, bulk moduli, volume thermal expansion coefficients and enthalpies of these polymorphs of Ge0(2) were simulated. In spite of the simple form of the potential, these simulated structural values, bulk moduli and thermal expansivities are in excellent agreement with the reliable experimental data in respect to both polymorphs. Using this potential, MD simulation was further used to study the structural changes of Ge02 under high pressure. We have investigated the pressure-induced amorphization. As reported in previous experimental studies, quartz-type GeO2 undergoes pressure-induced crystalline-to-amorphous transformation at room temperature, the same as other quartz compounds; SiO2, AlPO4. Under hydrostatic compression, in this study, alpha-quartz-type GeO2 transformed to a denser amorphous state at 7.4 GPa with change of the packing of oxygen ions and increase of germanium coordination. At higher pressure still, rutile-type GeO2 transformed to a new phase of CaCl2-type structure as a post-rutile candidate.
  • T Nagai, T Hattori, T Tsuchiya, T Yamanaka
    SOLID STATE COMMUNICATIONS 107 5 223 - 225 1998年 研究論文(学術雑誌) 
    Pressure-induced phase transition from high pressure clinopyroxene type FeGeO3 to its perovskite polymorph has been observed for the first time. X-ray measurements were conducted at 40 GPa and at room temperature. The material is indexed on an orthorhombic lattice, with unit cell parameters a = 4.93 +/- 0.02 Angstrom, b = 5.06 +/- 0.05 Angstrom, c = 6.66 +/- 0.03 Angstrom and V = 166.1 +/- 0.8 Angstrom(3) at 40 GPa. The pressure-induced transition to FeGeO3-perovskite occurs during room temperature compression of the high pressure clinopyroxene type of FeGeO3. Furthermore, FeGeO3-perovskite was transformed into the lithium niobate structure during decompression This phase was indexed on a hexagonal lattice, with unit cell parameters a = 5.05 +/- 0.04 Angstrom, c = 14.2 +/- 0.2 Angstrom and V = 313.6 +/- 1.2 Angstrom(3) at ambient pressure. (C) 1998 Elsevier Science Ltd. All rights reserved.
  • EXAFS study on the anharmonic effective pair potential in rutile type, α-quartz type GeO2
    EDP SciencesJournal de Physique IV, Colloque 7 C2-1175-1176  1997年
  • Mechanism of pressure-induced amorphization
    T Yamanaka, T Nagai, T Tsuchiya
    ZEITSCHRIFT FUR KRISTALLOGRAPHIE 212 6 401 - 410 1997年 
    Several crystalline substances have been found to be transformed into the amorphous state under compressed condition at kinetically low temperature. Dynamical lattice-instability due to elastic deformation by shear and stress induces the reversible amorphization, some of which produces memory glass. On the other hand the irreversible modes are attributed to the plastic deformation by the nucleation of high-pressure form in the parent lattice but thermal energy is not kinetically high enough to provide the large crystallite size coherent to the X-ray radiation. They can be defined as X-ray amorphous. These reversible and irreversible transformations arise from the hindrance to sufficient atomic mobility. These pressure-induced amorphizations are the precursor phenomena of the phase transformation to high-pressure polymorphs. Successive structure changes of the pressure-induced amorphization are investigated under various pressure and temperature by X-ray diffractometry, EXAFS and Raman spectroscopy. The amorphization has been also simulated by the molecular dynamics.
  • GEL-FORMING CHARACTERISTICS OF FISH MEAT PROTEINS
    T TSUCHIYA, T SANO
    JOURNAL OF THE JAPANESE SOCIETY FOR FOOD SCIENCE AND TECHNOLOGY-NIPPON SHOKUHIN KAGAKU KOGAKU KAISHI 35 5 367 - 376 1988年 [査読有り]
     研究論文(学術雑誌)

書籍

  • Post-Perovskite: The Last Mantle Phase Transition (AGU Geophysical Monograph Series 174)
    American Geophysical Union 2007年
  • Treatise on Geophysics
    Elsevier 2007年
  • Superplumes: Beyond Plate Tectonics
    Springer 2007年
  • Post-Perovskite: The Last Mantle Phase Transition (AGU Geophysical Monograph Series 174)
    American Geophysical Union 2007年
  • Treatise on Geophysics
    Elsevier 2007年
  • Superplumes: Beyond Plate Tectonics
    Springer 2007年
  • Physicochemistry of Water in Geological and Biological Systems
    Universal Academy Press 2004年
  • Physicochemistry of Water in Geological and Biological Systems
    Universal Academy Press 2004年
  • Physicochemistry of Water in Geological and Biological Systems
    Universal Academy Press 2004年
  • Physicochemistry of Water in Geological and Biological Systems
    Universal Academy Press 2004年
  • Physics Meets Mineralogy
    Cambridge University Press 2000年
  • Physics Meets Mineralogy
    Cambridge University Press 2000年

講演・口頭発表等

  • Deep Earth science from quantum physics  [招待講演]
    T. Tsuchiya
    Physics Summer Research Experience 2019年08月 公開講演,セミナー,チュートリアル,講習,講義等
  • Ab initio molecular dynamics study of atomic diffusion in covalent liquid under high pressure  [招待講演]
    S. Omura, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 口頭発表(招待・特別)
  • First-principles prediction of hydrogen partitioning between the core and mantle  [通常講演]
    S. Ritterbex, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 口頭発表(一般)
  • Structural and transport properties of liquid iron-light-element mixtures under outer core conditions
    S. Omura, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 口頭発表(一般)
  • Origin and role of lost continents  [通常講演]
    S. Maruyama, K. Kawai, S. Gréaux, T. Tsuchiya, T. Cho
    日本地球惑星科学連合2019年大会 2019年05月 口頭発表(一般)
  • First-principles prediction of hydrogen partitioning between the core and mantle  [通常講演]
    A. Ohba, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 ポスター発表
  • Ab initio anharmonic lattice dynamics for Fe-bearing lower mantle minerals  [通常講演]
    H. Dekura, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 口頭発表(一般)
  • Stable carbon isotope fractionation in Fe-C system from first principles  [通常講演]
    H. Dekura, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 ポスター発表
  • Lateral heterogeneity in the lowermost outer core (F layer) of the Earth revealed by seismic analyses  [通常講演]
    T. Otaki, S. Kaneshima, T. Tsuchiya
    日本地球惑星科学連合2019年大会 2019年05月 ポスター発表
  • Elasticity of Fe-Si Alloy  [通常講演]
    T. Tsuchiya, Y. Fukunaga
    日本地球惑星科学連合2019年大会 2019年05月 口頭発表(一般)
  • Ab initio anharmonic lattice dynamics for Fe-bearing lower mantle minerals  [通常講演]
    H. Dekura, T. Tsuchiya
    Joint symposium of Misasa 2019 & Core-Mantle Coevolution 2019年03月 ポスター発表
  • Ab-Initio Investigation of Iron Self-Diffusion: Implications for the Plasticity of Earth’s Inner Core  [通常講演]
    S. Ritterbex, T. Tsuchiya
    Joint symposium of Misasa 2019 & Core-Mantle Coevolution 2019年03月 口頭発表(一般)
  • Ab Initio Applications to the Element Partitioning between Core and Mantle  [通常講演]
    T. Tsuchiya, A. Ohba, Z. Xiong
    Joint symposium of Misasa 2019 & Core-Mantle Coevolution 2019年03月 口頭発表(一般)
  • Ab-initio Study of Iron Diffusion Properties with Implications to Inner Core Plasticity  [通常講演]
    S. Ritterbex, T. Tsuchiya
    AGU Fall Meeting 2018 2018年12月 ポスター発表
  • High-P,T elasticity of Fe-Si and Fe-S alloys  [通常講演]
    T. Tsuchiya
    AGU Fall Meeting 2018 2018年12月 ポスター発表
  • He and Ar partitioning between liquid iron and molten silicate at high pressure  [通常講演]
    Z. Xiong, T. Tsuchiya
    IMA 22nd Meeting 2018年08月 口頭発表(一般)
  • How the B1-B2 phase transition changes diffusion properties of MgO in super-Earth mantles  [通常講演]
    S. Ritterbex, T. Harada, T. Tsuchiya
    IMA 22nd Meeting 2018年08月 口頭発表(一般) メルボルン IMA
  • First principles investigation of the high-pressure behavior of the FeOOH-AlOOH-phase H (MgSiO4H2) system  [通常講演]
    土屋旬, 土屋卓久, 西真之, 桑山 靖弘
    IMA 22nd Meeting 2018年08月 口頭発表(一般)
  • He and Ar partitioning between liquid iron and molten silicate at high pressure  [通常講演]
    T. Tsuchiya, Z. Xiong
    AOGS 15th Annual Meeting 2018年06月 口頭発表(一般)
  • First principles investigation of the high-pressure behavior of the FeOOH-AlOOH-Phase H system  [通常講演]
    J. Tsuchiya, T. Tsuchiya, M. Nishi, Y. Kuwayama
    AOGS 15th Annual Meeting 2018年06月 口頭発表(一般)
  • 第一原理物性計算による地球深部科学  [招待講演]
    土屋 卓久
    日本地球惑星科学連合ランチタイムスペシャルレクチャー 2018年05月 公開講演,セミナー,チュートリアル,講習,講義等
  • Ab-initio study of Earth's inner core diffusion properties and the effect of light elements  [通常講演]
    S. Ritterbex, T. Tsuchiya
    日本地球惑星科学連合2018年大会 2018年05月 口頭発表(一般)
  • He and Ar partitioning between liquid iron and molten silicate at high pressure  [通常講演]
    Z. Xiong, T. Tsuchiya
    日本地球惑星科学連合2018年大会 2018年05月 口頭発表(一般)
  • Implication of the B1-B2 phase transition on MgO diffusion properties in super-Earth mantles  [通常講演]
    S. Ritterbex, T. Harada, T. Tsuchiya
    日本地球惑星科学連合2018年大会 2018年05月 口頭発表(一般)
  • High-P,T easticity of Fe-Si and Fe-S alloys  [通常講演]
    土屋 卓久
    日本地球惑星科学連合2018年大会 2018年05月 口頭発表(一般)
  • Effects of iron on the lattice thermal conductivity of lower mantle minerals evaluated by Ab initio anharmonic lattice dynamics simulations  [通常講演]
    H. Dekura, T. Tsuchiya
    日本地球惑星科学連合2018年大会 2018年05月 口頭発表(一般)
  • Effects of light elements on transport properties of liquid Fe alloys under high pressure  [通常講演]
    S. Ohmura, T. Tsuchiya, H. Ichikawa
    日本地球惑星科学連合2018年大会 2018年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合
  • Ferric iron in MgO  [通常講演]
    土屋 卓久
    日本地球惑星科学連合2018年大会 2018年05月 ポスター発表
  • Ab initio lattice thermal conductivity of MgSiO3 post-perovskite  [通常講演]
    H. Dekura, T. Tsuchiya
    日本地球惑星科学連合2018年大会 2018年05月 ポスター発表
  • 地球深部の理解はどこまで進んでいるのか  [招待講演]
    土屋 卓久
    一般公開講演会「物理で明かす地球の深部,化学でひも解く地球の歴史,地震で探る日本の地下」 2018年03月 公開講演,セミナー,チュートリアル,講習,講義等 愛媛大学 愛媛大学
  • Ab Initio Predictions of K, He and Ar Partitioning Between Silicate Melt and Liquid Iron Under High Pressure  [通常講演]
    Z. Xiong, T. Tsuchiya, T. Taniuchi
    AGU Fall Meeting 2017 2017年12月 口頭発表(一般) ニューオーリンズ、アメリカ アメリカ地球物理学連合
  • Atomic scale study of vacancies in Earth’s inner core: effect of pressure and chemistry  [通常講演]
    S. Ritterbex, T. Tsuchiya
    AGU Fall Meeting 2017 2017年12月 口頭発表(一般) ニューオーリンズ、アメリカ アメリカ地球物理学連合
  • First principles investigation of high pressure behavior of FeOOH-AlOOH-phase H (MgSiO4H2) system  [招待講演]
    J. Tsuchiya, E. C. Thompson, T. Tsuchiya, M. Nishi, Y. Kuwayama
    AGU Fall Meeting 2017 2017年12月 口頭発表(招待・特別) ニューオーリンズ、アメリカ アメリカ地球物理学連合
  • High-P,T elasticity of iron-light element alloys  [通常講演]
    T. Tsuchiya, Y. Kuwayama, M. Ishii, K. Kawai
    AGU Fall Meeting 2017 2017年12月 口頭発表(一般) ニューオーリンズ、アメリカ アメリカ地球物理学連合
  • The high-pressure phase transitions of hydroxides  [招待講演]
    M. Nishi, Y. Kuwayama, J. Tsuchiya, T. Tsuchiya, T. Irifune
    AGU Fall Meeting 2017 2017年12月 口頭発表(招待・特別) ニューオーリンズ、アメリカ アメリカ地球物理学連合
  • High-pressure phase transitions in AlOOH and FeOOH, High-Pressure Mineral Physics Seminar (HPMPS-9)  [招待講演]
    西 真之, 桑山 靖弘, 土屋 旬, 土屋 卓久, 入舩徹男
    High-Pressure Mineral Physics Seminar (HPMPS-9) 2017年09月 口頭発表(招待・特別) サンマロ(フランス)
  • Theory and computation for high-pressure mineral physics  [招待講演]
    Taku Tsuchiya, Jun Tsuchiya, Haruhiko Dekura, Zhihua Xiong, Sebastian Arthur Willem Ritterbex, Xianlong Wang, Hiroki Ichikawa
    High-Pressure Mineral Physics Seminar (HPMPS-9) 2017年09月 口頭発表(基調) サンマロ(フランス)
  • Theoretical mineral physics for mantle science  [通常講演]
    土屋 卓久
    AIRAPT26 Joint with ACHPR 8 & CHPC 19 2017年08月 口頭発表(一般) 中国ナショナルコンベンションセンター、北京、中国
  • Lattice thermal conductivity of Earth's lower mantle minerals from first principles  [通常講演]
    Haruhiko Dekura, Taku Tsuchiiya
    AIRAPT26 Joint with ACHPR 8 & CHPC 19 2017年08月 ポスター発表 中国ナショナルコンベンションセンター、北京、中国
  • First principles investigation of the high-pressure behavior of the FeOOH-AlOOH- phase H (MgSiO4H2) system  [招待講演]
    Jun Tsuchiya, Elizabeth C. Thompson, Taku Tsuchiya, Masayuki Nishi, Yasuhiro Kuwayama
    IAG-IASPEI 2017 2017年08月 口頭発表(招待・特別) 神戸コンベンションションセンター(兵庫県神戸市)
  • 土屋 卓久, 桑山 靖弘, 石井 水晶, 河合 研志
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 大滝 壽樹, 金嶋 聰, 市川 浩樹, 土屋 卓久
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 大村 訓史, 土屋 卓久, 市川 浩樹
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 大村 訓史, 土屋 卓久
    JpGU-AGU Joint Meeting 2017 2017年05月 ポスター発表 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 市川 浩樹, 土屋 卓久
    JpGU-AGU Joint Meeting 2017 2017年05月 ポスター発表 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 出倉 春彦, 土屋 卓久
    JpGU-AGU Joint Meeting 2017 2017年05月 ポスター発表 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • Sebastian Arthur Willem Ritterbex, Taku Tsuchiya
    JpGU-AGU Joint Meeting 2017 2017年05月 ポスター発表 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • TSUCHIYA Taku
    西 真之、桑山 靖弘、土屋 旬、土屋 卓久 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 土屋 旬, 土屋 卓久, 西 真之, 桑山 靖弘
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 出倉 春彦, 土屋 卓久
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • Zhihua Xiong, Taku Tsuchiya, Takashi Taniuchi
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(一般) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • Xianlong Wang, Taku Tsuchiya, Zhi Zeng
    JpGU-AGU Joint Meeting 2017 2017年05月 口頭発表(招待・特別) 幕張メッセ(千葉県千葉市) 日本地球惑星連合、アメリカ地球物理学連合
  • 地球中心にはどのような物質があるのか?  [招待講演]
    土屋 卓久
    第55回玉城嘉十郎教授記念公開学術講演会 -明らかにされる太陽系と地球深部の固体物質- 2016年12月 公開講演,セミナー,チュートリアル,講習,講義等 京都大学(京都府)
  • 第一原理計算による地球内部物理学  [招待講演]
    土屋 卓久
    日本地球化学会年会 2016年09月 口頭発表(招待・特別) 大阪市立大学(大阪府大阪市)
  • 地球深部の理解はどこまで進んでいるのか  [招待講演]
    土屋 卓久
    愛媛大GRC・東大地震研協定記念講演会 2016年04月 公開講演,セミナー,チュートリアル,講習,講義等 愛媛大学(愛媛県松山市)

MISC

受賞

  • 2019年11月 日本高圧力学会 日本高圧力学会賞
     第一原理計算に基づく独自の計算技術の開発と高圧地球科学の新しい展開への多大な貢献
  • 2017年05月 日本地球惑星科学連合 地球惑星科学振興西田賞
     第一原理計算による地球深部ダイナミクスの研究 
    受賞者: 土屋 卓久
  • 2014年09月 日本鉱物科学会 日本鉱物科学会賞
     第一原理計算による理論高圧鉱物物性学の開拓 
    受賞者: 土屋 卓久
  • 2011年03月 日本学術振興会 日本学術振興会賞
     地球惑星深部物質および関連物質の理論的計算物理学的研究 JPN 
    受賞者: 土屋 卓久
  • 2009年04月 文部科学省 文部科学大臣表彰若手科学者賞
     第一原理シミュレーションによる地球下部マントル物質の研究 JPN 
    受賞者: 土屋 卓久
  • 2006年01月 Thomson-Reuters New Hot Papers
  • 2004年08月 American Geophysical Union AGU Journal Highlights
  • 2003年11月 日本高圧力学会 奨励賞
     地球内部物質と関連物質の電子状態理論研究 JPN 
    受賞者: 土屋卓久
  • 2003年09月 日本粘土学会 論文賞
     JPN

委員歴

  • 2008年 - 2009年   日本高圧力学会   AIRAPT組織委員会 プログラム委員   日本高圧力学会
  • 2006年 - 2008年   日本高圧力学会   渉外幹事   日本高圧力学会
  • 2006年 - 2008年   日本高圧力学会   評議員   日本高圧力学会

愛媛大学教員活動実績

教育活動(B)

担当授業科目(B01)

  • 2019, 前期, 学部, 地球科学実験Ⅰ
  • 2019, 前期, 修士, 地球科学高等実験Ⅰ
  • 2019, 前期, 修士, 地球科学高等実験Ⅱ
  • 2019, 前期, 修士, 地球科学高等実験Ⅴ
  • 2019, 前期, 修士, 地球科学高等実験Ⅵ
  • 2019, 前期, 修士, 地球科学プレゼンテーション特別実習Ⅰ
  • 2019, 前期, 修士, 地球科学プレゼンテーション特別実習Ⅲ
  • 2019, 前期, 修士, 地球科学ゼミナールⅠ
  • 2019, 前期, 修士, 地球科学プレゼンテーション特別実習Ⅱ
  • 2019, 前期, 修士, 地球科学高等実験Ⅲ
  • 2019, 前期, 学部, 地球科学実験I


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