Faculty Profiles - Ishii Takayuki

Papers - Ishii Takayuki

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High-Pressure Phase Relations and Element Partitioning of Minerals in Hydrous Systems Invited Reviewed

Takayuki ISHII, Eiji OHTANI

The Review of High Pressure Science and Technology 33 ( 3 ) 179 - 186 2023.9

Buoyancy of slabs and plumes enhanced by curved post-garnet phase boundary Reviewed

Takayuki Ishii, Daniel J. Frost, Eun Jeong Kim, Artem Chanyshev, Keisuke Nishida, Biao Wang, Rintaro Ban, Jianing Xu, Jin Liu, Xiaowan Su, Yuji Higo, Yoshinori Tange, Ho-kwang Mao, Tomoo Katsura

Nature Geoscience 2023.9

High-pressure phase transition and equation of state of hydrous Al-bearing silica Reviewed

Giacomo Criniti, Takayuki Ishii, Alexander Kurnosov, Konstantin Glazyrin, Tiziana Boffa Ballaran

American Mineralogist 108 ( 8 ) 1558 - 1568 2023.8

Iron and aluminum substitution mechanism in the perovskite phase in the system MgSiO3-FeAlO3-MgO Reviewed

Takayuki Ishii, Catherine McCammon, Tomoo Katsura

American Mineralogist 108 ( 4 ) 738 - 743 2023.4

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

Abstract

Fe,Al-bearing MgSiO3 perovskite (bridgmanite) is considered to be the most abundant mineral in Earth’s lower mantle, hosting ferric iron in its structure as charge-coupled (Fe2O3 and FeAlO3) and vacancy components (MgFeO2.5 and Fe2/3SiO3). We examined concentrations of ferric iron and aluminum in the perovskite phase as a function of temperature (1700–2300 K) in the MgSiO3-FeAlO3-MgO system at 27 GPa using a multi-anvil high-pressure apparatus. We found a LiNbO3-structured phase in the quenched run product, which was the perovskite phase under high pressures and high temperatures. The perovskite phase coexists with corundum and a phase with (Mg,Fe3+,☐)(Al,Fe3+)2O4 composition (☐ = vacancy). The FeAlO3 component in the perovskite phase decreases from 69 to 65 mol% with increasing temperature. The Fe2O3 component in the perovskite phase remains unchanged at ~1 mol% with temperature. The A-site vacancy component of Fe2/3SiO3 in the perovskite phase exists as 1–2 mol% at 1700–2000 K, whereas 1 mol% of the oxygen vacancy component of MgFeO2.5 appears at higher temperatures, although the analytical errors prevent definite conclusions. The A-site vacancy component might be more important than the oxygen vacancy component for the defect chemistry of bridgmanite in slabs and for average mantle conditions when the FeAlO3 charge-coupled component is dominant.

DOI： 10.2138/am-2022-8457

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Equation of State and Spin Crossover of (Al, Fe)‐Phase H Reviewed

Benjamin Strozewski, Johannes Buchen, Wolfgang Sturhahn, Takayuki Ishii, Itaru Ohira, Stella Chariton, Barbara Lavina, Jiyong Zhao, Thomas S. Toellner, Jennifer M. Jackson

Journal of Geophysical Research: Solid Earth 128 ( 4 ) 2023.4

Ferric Iron Substitution Mechanism in Bridgmanite under SiO₂-Saturated Conditions at 27 GPa Reviewed

Artem Chanyshev, Hongzhan Fei, Dmitry Bondar, Biao Wang, Zhaodong Liu, Takayuki Ishii, Robert Farla, Catherine McCammon, Tomoo Katsura

ACS Earth and Space Chemistry 7 ( 2 ) 471 - 478 2023.2

Stability of Fe5O6 and its relation to other Fe-Mg-oxides at high pressures and temperatures Reviewed

Alan B. Woodland, Laura Uenver-Thiele, Tiziana Boffa Ballaran, Nobuyoshi Miyajima, Kevin Rosbach, Takayuki Ishii

American Mineralogist 108 ( 1 ) 140 - 149 2023.1

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

Abstract

The stability of Fe5O6 has been experimentally determined under pressure-temperature conditions relevant for the Earth’s deeper upper mantle down to the upper portion of the lower mantle (to 28 GPa). In addition, we investigated the incorporation of Mg into Fe5O6 and its systematics, which allows us to discuss the relevance of this phase for the mantle. Experiments were performed from 8–28 GPa and 900–1600 °C. Additional oxide phases may appear if the bulk composition does not maintain the Fe32+Fe23+O6 stoichiometry during the experiment, including coexisting Fe4O5 or Fe9O11. Unfortunately, the similarities in Raman spectra between several high-pressure Fe-oxide phases make this method unsuitable for distinguishing which phase is present in a given sample. The stability field for Fe5O6 extends from ~9 to at least 28 GPa but is truncated at lower temperatures by the assemblage Fe4O5 + wüstite. Refined thermodynamic properties for Fe5O6 are presented. The range of redox stability of Fe5O6 appears to be more limited than that of Fe4O5.

Solid solution along the Fe5O6-Mg3Fe2O6 binary is quite limited, reaching a maximum Mg content of ~0.82 cations per formula unit (i.e., XMg3Fe2O6 ≈ 0.27) at 1400 °C and 10 GPa. The observed sharp decrease in molar volume of the O6-phase with Mg content could be a possible explanation for the limited range of solid solution. A phase diagram has been constructed for a composition of approximately Mg0.5Fe2.52+Fe23+O6 stoichiometry. This small amount of Mg causes a significant change in the relations between the O6-structured phase and the assemblage O5-structured phase + (Mg,Fe)O. Several experiments were performed to test whether the O6-phase can coexist with mantle silicates like wadsleyite and ringwoodite. In all cases, the run products contained (Mg,Fe)2Fe2O5 rather than the O6-phase, further underlining the limited ability of Fe5O6 to accommodate enough Mg to be stable in a mantle assemblage.

The large stability field of Fe5O6 implies that this phase could likely occur in locally Fe-rich environments, like those sampled by some “deep” diamonds. However, the limited solubility of Mg in the O6-phase leads us to conclude that the O5-phase should be of much more relevance as an accessory phase in a peridotitic mantle assemblage.

DOI： 10.2138/am-2022-8370

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Synthesis and structural analysis of CaFe2O4-type single crystals in the NaAlSiO4-MgAl2O4-Fe3O4 system Reviewed

Takayuki Ishii, Giacomo Criniti, Xiaoyu Wang, Konstantin Glazyrin, Tiziana Boffa Ballaran

American Mineralogist 108 ( 1 ) 217 - 221 2023.1

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

Abstract

Orthorhombic CaFe2O4-structured (Cf) Na-rich aluminous silicate (space group Pbnm) is a major mineral of metabasaltic rocks at lower mantle conditions and can, therefore, significantly affect the physical properties of subducted oceanic crusts. We attempted to synthesize single crystals of Cf-type phases in the systems NaAlSiO4, NaAlSiO4-MgAl2O4, NaAlSiO4-MgAl2O4-Fe3O4, and NaAlSiO4-MgAl2O4-Fe3O4-H2O at 23–26 GPa and 1100–2200 °C. Under dry conditions, single crystals of Cf-type phase up to 100–150 μm in size were recovered from 23 GPa and 2000–2200 °C. Single-crystal X-ray diffraction and composition analyses suggest that the synthesized Cf-type phases have a few percent of vacancies in the eightfold-coordinated site with Na, Mg, and Fe2+ and partially disordered Al and Si in the octahedral sites. Iron-bearing Cf-type phases have 32–34% Fe3+ that is hosted both in the octahedral sites and in the eightfold-coordinated site. In NaAlSiO4-MgAl2O4-Fe3O4-H2O system, no formation of Cf-type phase was observed at 24 GPa and 1100–2000 °C due to the formation of hydrous Na-rich melt and Al-rich oxides or hydroxides, suggesting the possible absence of Cf-type phase in the hydrous basaltic crust. The single-crystal syntheses of Cf-type phases will be useful for investigating their physical properties, potentially improving models of lower mantle structure and dynamics.

DOI： 10.2138/am-2022-8748

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The influence of Al2O3 on the structural properties of MgSiO3 akimotoite Reviewed

Nicki C. Siersch, Giacomo Criniti, Alexander Kurnosov, Tiziana Boffa Ballaran, Zhaodong Liu, Takayuki Ishii, Daniel J. Frost, Tony Yu, Yanbin Wang

American Mineralogist 108 ( 1 ) 100 - 109 2023.1

Publishing type：Research paper (scientific journal) Publisher：Mineralogical Society of America

Abstract

Akimotoite, a MgSiO3 polymorph present in the lower transition zone within ultramafic portions of subducting slabs and potentially also in the ambient mantle, will partition some amount of Al, raising the question of how this will affect its crystal structure and properties. In this study, a series of samples along the MgSiO3-Al2O3 (akimotoite-corundum) solid solution have been investigated by means of single-crystal X-ray diffraction to examine their crystal chemistry. Results show a strong nonlinear behavior of the a- and c-axes as a function of Al content, which arises from fundamentally different accommodation mechanisms in the akimotoite and corundum structures. Furthermore, two Al2O3-bearing akimotoite samples were investigated at high pressure to determine the different compression mechanisms associated with Al substitution. Al2O3-bearing akimotoite becomes more compressible at least up to 20 mol% Al2O3, due likely to an increase in compressibility as the Al cation is incorporated into the SiO6 octahedron. This observation is in strong contrast to the stiffer corundum end-member having a KT = 250 GPa, which is larger than that of the akimotoite end-member [KT = 205(1) GPa]. These findings have implications for mineral physics models of elastic properties, which have in the past assumed linear mixing behavior between the MgSiO3 akimotoite and Al2O3 corundum end-members to calculate sound wave velocities for Al-bearing akimotoite at high pressure and temperature.

DOI： 10.2138/am-2022-8257

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Superhydrous aluminous silica phases as major water hosts in high-temperature lower mantle Reviewed

Takayuki Ishii, Giacomo Criniti, Eiji Ohtani, Narangoo Purevjav, Hongzhan Fei, Tomoo Katsura, Ho-kwang Mao

Proceedings of the National Academy of Sciences 119 ( 44 ) 2022.10

Authorship：Lead author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：Proceedings of the National Academy of Sciences

Water transported by subducted oceanic plates changes mineral and rock properties at high pressures and temperatures, affecting the dynamics and evolution of the Earth’s interior. Although geochemical observations imply that water should be stored in the lower mantle, the limited amounts of water incorporation in pyrolitic lower-mantle minerals suggest that water in the lower mantle may be stored in the basaltic fragments of subducted slabs. Here, we performed multianvil experiments to investigate the stability and water solubility of aluminous stishovite and CaCl ₂ -structured silica, referred to as poststishovite, in the SiO ₂ -Al ₂ O ₃ -H ₂ O systems at 24 to 28 GPa and 1,000 to 2,000 °C, representing the pressure–temperature conditions of cold subducting slabs to hot upwelling plumes in the top lower mantle. The results indicate that both alumina and water contents in these silica minerals increase with increasing temperature under hydrous conditions due to the strong Al ³⁺ -H ⁺ charge coupling substitution, resulting in the storage of water up to 1.1 wt %. The increase of water solubility in these hydrous aluminous silica phases at high temperatures is opposite of that of other nominally anhydrous minerals and of the stability of the hydrous minerals. This feature prevents the releasing of water from the subducting slabs and enhances the transport water into the deep lower mantle, allowing significant amounts of water storage in the high-temperature lower mantle and circulating water between the upper mantle and the lower mantle through subduction and plume upwelling. The shallower depths of midmantle seismic scatterers than expected from the pure SiO ₂ stishovite–poststishovite transition pressure support this scenario.

DOI： 10.1073/pnas.2211243119

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Sound Velocity Measurements of B2‐Fe‐Ni‐Si Alloy Under High Pressure by Inelastic X‐Ray Scattering: Implications for the Composition of Earth's Core Reviewed

S. Dominijanni, C. A. McCammon, E. Ohtani, D. Ikuta, T. Sakamaki, T. Ishii, G. Criniti, L. S. Dubrovinsky, S. Khandarkhaeva, T. Fedotenko, K. Glazyrin, H. Uchiyama, H. Fukui, A. Q. R. Baron

Geophysical Research Letters 49 ( 15 ) 2022.8

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

Abstract

Elastic properties of B2‐Fe_0.67Ni_0.06Si_0.27 (15 wt.% Si) alloy have been investigated by combined high‐resolution inelastic X‐ray scattering and powder X‐ray diffraction in diamond anvil cells up to 100 GPa at room temperature. Densities (ρ), compressional (V_P) and shear (V_S) wave velocities were extrapolated to inner core conditions to enable comparison with the preliminary reference Earth model. The modeled aggregate compressional and shear wave velocities and densities of the two‐phase mixture of B2‐Fe_0.67Ni_0.06Si_0.27 and hcp‐Fe‐Ni are consistent with inner core PREM values of V_P,V_S, and ρ based on a linear mixing model with 30(5) vol % B2‐Fe_0.67Ni_0.06Si_0.27 and 70(5) vol % hcp Fe‐Ni, which corresponds to ∼3–5 wt.% Si and ∼5–12 wt.% Ni.

DOI： 10.1029/2021gl096405

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Other Link： https://onlinelibrary.wiley.com/doi/full-xml/10.1029/2021GL096405

A New Approach Determining a Phase Transition Boundary Strictly Following a Definition of Phase Equilibrium: An Example of the Post-Spinel Transition in Mg2SiO4 System Invited Reviewed

Takayuki Ishii, Artem Chanyshev, Tomoo Katsura

Minerals 12 ( 7 ) 820 - 820 2022.6

Authorship：Lead author,　Corresponding author Publishing type：Research paper (scientific journal) Publisher：MDPI AG

The Clapeyron slope is the slope of a phase boundary in P–T space and is essential for understanding mantle dynamics and evolution. The phase boundary is delineating instead of balancing a phase transition’s normal and reverse reactions. Many previous high pressure–temperature experiments determining the phase boundaries of major mantle minerals experienced severe problems due to instantaneous pressure increase by thermal pressure, pressure drop during heating, and sluggish transition kinetics. These complex pressure changes underestimate the transition pressure, while the sluggish kinetics require excess pressures to initiate or proceed with the transition, misinterpreting the phase stability and preventing tight bracketing of the phase boundary. Our recent study developed a novel approach to strictly determine phase stability based on the phase equilibrium definition. Here, we explain the details of this technique, using the post-spinel transition in Mg2SiO4 determined by our recent work as an example. An essential technique is to observe the change in X-ray diffraction intensity between ringwoodite and bridgmanite + periclase during the spontaneous pressure drop at a constant temperature and press load with the coexistence of both phases. This observation removes the complicated pressure change upon heating and kinetic problem, providing an accurate and precise phase boundary.

DOI： 10.3390/min12070820

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Low Thermal Conductivity of Hydrous Phase D Leads to a Self‐Preservation Effect Within a Subducting Slab Reviewed

Wen‐Pin Hsieh, Enrico Marzotto, Takayuki Ishii, Leonid Dubrovinsky, Alena A. Aslandukova, Giacomo Criniti, Yi‐Chi Tsao, Chun‐Hung Lin, Jun Tsuchiya, Eiji Ohtani

Journal of Geophysical Research: Solid Earth 127 ( 6 ) 2022.6

Structural independence of hydrogen-bond symmetrisation dynamics at extreme pressure conditions Reviewed

Thomas Meier, Florian Trybel, Saiana Khandarkhaeva, Dominique Laniel, Takayuki Ishii, Alena Aslandukova, Natalia Dubrovinskaia, Leonid Dubrovinsky

Nature Communications 13 ( 1 ) 2022.6

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

Abstract

The experimental study of hydrogen-bonds and their symmetrization under extreme conditions is predominantly driven by diffraction methods, despite challenges of localising or probing the hydrogen subsystems directly. Until recently, H-bond symmetrization has been addressed in terms of either nuclear quantum effects, spin crossovers or direct structural transitions; often leading to contradictory interpretations when combined. Here, we present high-resolution in-situ ¹H-NMR experiments in diamond anvil cells investigating a range of systems containing linear O-H ⋯ O units at pressure ranges of up to 90 GPa covering their respective H-bond symmetrization. We found pronounced minima in the pressure dependence of the NMR resonance line-widths associated with a maximum in hydrogen mobility, precursor to a localisation of hydrogen atoms. These minima, independent of the chemical environment of the O-H ⋯ O unit, can be found in a narrow range of oxygen oxygen distances between 2.44 and 2.45 Å, leading to an average critical oxygen-oxygen distance of $${\bar{r } }_{ { { { { { { { \rm{OO } } } } } } } } }^{ { { { { { { { \rm{crit } } } } } } } } }=2.443(1)$$ Å.

DOI： 10.1038/s41467-022-30662-4

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Other Link： https://www.nature.com/articles/s41467-022-30662-4

The electrical conductivity of Fe4O5, Fe5O6, and Fe7O9 up to 60 GPa Reviewed

Shuhou Maitani, Ryosuke Sinmyo, Takayuki Ishii, Saori I. Kawaguchi, Naohisa Hirao

Physics and Chemistry of Minerals 49 ( 5 ) 2022.5

Equations of state of α-SiC (6H) and βʹ-Mg2Si1.1 from single-crystal X-ray diffraction data and novel high-pressure magnesium silicide Mg2Si7 Reviewed

Iuliia Koemets, Takayuki Ishii, Michael Hanfland, Leonid Dubrovinsky

Physics and Chemistry of Minerals 49 ( 5 ) 2022.5

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

Abstract

SiC and (Fe, Mg)-silicide are candidate phases forming under reducing conditions in the Earth and planetary interiors. However, structural studies of SiC and Mg₂Si at high pressure and their thermal stability are presently lacking. In this work, we applied single-crystal X-ray diffraction in a diamond anvil cell at high pressure and determined the equations of state of α-SiC (6H) and βʹ-Mg₂Si_1.1 up to 60 and 40 GPa, respectively, yielding bulk moduli of 226.0(4) and 56(1) GPa. We also report the formation of a novel orthorhombic Mg₂Si₇ phase upon laser heating βʹ-Mg₂Si_1.1 at ~ 45 GPa and 2000 °C [Pbam, a = 7.16(1) Å, b = 12.490(3) Å, c = 2.6545(3) Å, V = 237.5(3) Å³]. The structure of this compound contains layers formed by irregular 12-member silicon rings, which are arranged in channels filled with both Mg and Si atoms. No signs of the Mg₂Si₇ phase were detected upon releasing the pressure in the DAC, which suggests that this phase is unstable under ambient conditions.

DOI： 10.1007/s00269-022-01189-3

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Other Link： https://link.springer.com/article/10.1007/s00269-022-01189-3/fulltext.html

Aluminum and hydrogen partitioning between bridgmanite and high-pressure hydrous phases: Implications for water storage in the lower mantle Reviewed

Takayuki Ishii, Eiji Ohtani, Anton Shatskiy

Earth and Planetary Science Letters 583 117441 - 117441 2022.4

High pressure-temperature phase relations of basaltic crust up to mid-mantle conditions Reviewed

Takayuki Ishii, Nobuyoshi Miyajima, Giacomo Criniti, Qingyang Hu, Konstantin Glazyrin, Tomoo Katsura

Earth and Planetary Science Letters 584 117472 - 117472 2022.4

Extreme conditions research using the large-volume press at the P61B endstation, PETRA III Reviewed

Robert Farla, Shrikant Bhat, Stefan Sonntag, Artem Chanyshev, Shuailing Ma, Takayuki Ishii, Zhaodong Liu, Adrien Néri, Norimasa Nishiyama, Guilherme Abreu Faria, Thomas Wroblewski, Horst Schulte-Schrepping, Wolfgang Drube, Oliver Seeck, Tomoo Katsura

Journal of Synchrotron Radiation 29 ( 2 ) 409 - 423 2022.2

Publishing type：Research paper (scientific journal) Publisher：International Union of Crystallography (IUCr)

Penetrating, high-energy synchrotron X-rays are in strong demand, particularly for high-pressure research in physics, chemistry and geosciences, and for materials engineering research under less extreme conditions. A new high-energy wiggler beamline P61 has been constructed to meet this need at PETRA III in Hamburg, Germany. The first part of the paper offers an overview of the beamline front-end components and beam characteristics. The second part describes the performance of the instrumentation and the latest developments at the P61B endstation. Particular attention is given to the unprecedented high-energy photon flux delivered by the ten wigglers of the PETRA III storage ring and the challenges faced in harnessing this amount of flux and heat load in the beam. Furthermore, the distinctiveness of the world's first six-ram Hall-type large-volume press, Aster-15, at a synchrotron facility is described for research with synchrotron X-rays. Additionally, detection schemes, experimental strategies and preliminary data acquired using energy-dispersive X-ray diffraction and radiography techniques are presented.

DOI： 10.1107/s1600577522001047

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Depressed 660-km discontinuity caused by akimotoite–bridgmanite transition Reviewed

Artem Chanyshev, Takayuki Ishii, Dmitry Bondar, Shrikant Bhat, Eun Jeong Kim, Robert Farla, Keisuke Nishida, Zhaodong Liu, Lin Wang, Ayano Nakajima, Bingmin Yan, Hu Tang, Zhen Chen, Yuji Higo, Yoshinori Tange, Tomoo Katsura

Nature 601 ( 7891 ) 69 - 73 2022.1

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

Abstract

The 660-kilometre seismic discontinuity is the boundary between the Earth’s lower mantle and transition zone and is commonly interpreted as being due to the dissociation of ringwoodite to bridgmanite plus ferropericlase (post-spinel transition)^1–3. A distinct feature of the 660-kilometre discontinuity is its depression to 750 kilometres beneath subduction zones^4–10. However, in situ X-ray diffraction studies using multi-anvil techniques have demonstrated negative but gentle Clapeyron slopes (that is, the ratio between pressure and temperature changes) of the post-spinel transition that do not allow a significant depression^11–13. On the other hand, conventional high-pressure experiments face difficulties in accurate phase identification due to inevitable pressure changes during heating and the persistent presence of metastable phases^1,3. Here we determine the post-spinel and akimotoite–bridgmanite transition boundaries by multi-anvil experiments using in situ X-ray diffraction, with the boundaries strictly based on the definition of phase equilibrium. The post-spinel boundary has almost no temperature dependence, whereas the akimotoite–bridgmanite transition has a very steep negative boundary slope at temperatures lower than ambient mantle geotherms. The large depressions of the 660-kilometre discontinuity in cold subduction zones are thus interpreted as the akimotoite–bridgmanite transition. The steep negative boundary of the akimotoite–bridgmanite transition will cause slab stagnation (a stalling of the slab’s descent) due to significant upward buoyancy^14,15.

DOI： 10.1038/s41586-021-04157-z

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Other Link： https://www.nature.com/articles/s41586-021-04157-z

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Papers - Ishii Takayuki