Faculty Profiles - Ishii Takayuki

Papers - Ishii Takayuki

Division display 1 - 20 of about 83 ／ All the affair displays >>

Synthesis, Stability, and Crystal Structure of CaTi₂O₄-Type ZnCr₂O₄: High-Pressure Crystal Chemistry of Postspinel Phases Reviewed

Takayuki Ishii, Yudai Masaki, Alan B. Woodland, Yoshiyuki Inaguma, Hiroshi Kojitani, Masaki Akaogi

Inorganic Chemistry 2025.6

Stability and water solubility of calcium ferrite-type aluminum-rich phase: implications for deep water cycle caused by subducting basaltic crusts

Xinyue Zhang, Izumi Mashino, Takayuki Ishii

Progress in Earth and Planetary Science 2025.5

Limited water contents of wadsleyite and ringwoodite coexisting with hydrous minerals in cold subducting slabs

Takayuki Ishii, Jintao Zhu, Eiji Ohtani

Earth and Planetary Science Letters 2025.5

Iron hydride (FeHx) as a crucial intermediate in transformation of subducted H2O to abiotic H2 in Earth’s deep mantle Reviewed

Jintao Zhu, Renbiao Tao, Takayuki Ishii, Daijo Ikuta, Wenbo Xu, Lifei Zhang, Yutong Su, Runchao Liu, Zhijun Jin

Science China Earth Sciences 68 ( 5 ) 1485 - 1496 2025.4

The effect of Fe incorporation on the single-crystal elasticity of δ-AlOOH Reviewed

Niccolò Satta, Giacomo Criniti, Tiziana Boffa Ballaran, Alexander Kurnosov, Takayuki Ishii, Johannes Buchen, Hauke Marquardt

Physics and Chemistry of Minerals 52 ( 2 ) 2025.4

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

Abstract

The seismic mapping of hydrous materials in the Earth’s deep interior requires experimental constraints on the elastic anisotropy of hydrous minerals and phases. Oxyhydroxides like δ-(Al,Fe)OOH are arguably the main hosts of water in the lower mantle. Therefore, constraints on the single-crystal elastic tensor of δ-(Al,Fe)OOH solid solutions are crucial to quantify the elastic anisotropy of this material, and advance the current understanding of the recycling of water into the lower mantle. Yet, experimental data for intermediate compositions are scarce, limiting the understanding of how Fe incorporation affects the single-crystal elastic properties of δ-AlOOH. In this study, we provide experimental constraints on the single-crystal elasticity of two δ-(Al,Fe)OOH solid solutions, with Fe/(Al + Fe) of 0.06(1) and 0.133(3). Large single-crystal samples of δ-(Al,Fe)OOH were synthetized at high pressures and temperatures using a multi-anvil press, and the full elastic stiffness tensors were determined at ambient conditions by combining X-ray diffraction and Brillouin scattering measurements. We show that replacing Al³⁺ with Fe³⁺ in δ-(Al,Fe)OOH lowers the magnitude of most coefficients of the elastic stiffness tensor (c _ij), which translates into a substantial reduction of aggregate moduli and acoustic wave velocities. We further show that, at ambient conditions, the acoustic anisotropy of δ-(Al,Fe)OOH displays no sensitivity to Fe–Al substitution.

DOI： 10.1007/s00269-025-01319-7

researchmap

Other Link： https://link.springer.com/article/10.1007/s00269-025-01319-7/fulltext.html

Effect of chemistry on the compressibility and high-pressure structural evolution of the CaFe2O4-type aluminous silicate phase Reviewed

Giacomo Criniti, Tiziana Boffa Ballaran, Alexander Kurnosov, Takayuki Ishii, Elena-Marie Rogmann, Konstantin Glazyrin, Timofey Fedotenko, Daniel J. Frost

Physics of the Earth and Planetary Interiors 361 107331 - 107331 2025.4

Development of high pressure-temperature experimental techniques and studies of phase relations and crystal chemistry of mantle minerals Reviewed

Takayuki ISHII

Japanese Magazine of Mineralogical and Petrological Sciences 54 ( 1 ) n/a - n/a 2025.2

Reduced Thermal Conductivity of Hydrous Aluminous Silica and Calcium Ferrite‐Type Phase Promote Water Transportation to Earth's Deep Mantle

Wen‐Pin Hsieh, Takayuki Ishii, Frédéric Deschamps, Yi‐Chi Tsao, Jen‐Wei Chang, Giacomo Criniti

Journal of Geophysical Research: Solid Earth 2025.1

Enhanced optical anisotropy of six-coordinated silica polymorphs via high-pressure hydrothermal treatment Reviewed

Junwei Li, Yanqiang Li, Weiqi Huang, Takayuki Ishii, Yanhao Lin, Binbin Yue, Sangen Zhao, Qingyang Hu

Journal of Materials Chemistry C 13 ( 3 ) 1499 - 1506 2025

Role of water in dynamics of slabs and surrounding mantle Reviewed

Eiji Ohtani, Takayuki Ishii

Progress in Earth and Planetary Science 11 ( 1 ) 2024.12

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

Abstract

Water bound to various hydrous minerals can be transported deep into the mantle by slab subduction. Serpentine is one of most important hydrous minerals in the crust and shallow upper mantle. A partially serpentinized slab mantle limits the amount of water that can enter deep into the mantle. The partitioning of water between hydrous minerals and nominally anhydrous minerals (NAMs) is a crucial factor in controlling the physical properties and dynamics of slabs. Recent experiments on water partitioning have revealed that water strongly partitions to coexisting hydrous minerals. NAMs, such as olivine and its high-pressure polymorphs, have limited water content in water-undersaturated wet slabs. Metastable olivine wedges are not a feature of dry slabs, but can be of wet slabs that are not saturated with water. The transformation kinetics of the dry state, which generates deep-focus earthquakes and produces significant deformation in the slab, can work under wet slabs. Water bound to hydrous minerals is transported by the slab to the mantle transition zone and lower mantle. Hydrous minerals in stagnant slabs over 660 km depth release water as the slab warms, producing locally hydrated mantle transition zones and dense water-bearing magmas at the base of the upper mantle, and generating intraplate volcanism, which are referred to as the big mantle wedge model. Seismic scatterers are observed in the lower mantle at depths from 700 to 1900 km. These scatterers may be caused by water release at the top of the lower mantle by dehydration of hydrous minerals such as dense hydrous magnesium silicates. The shear instability due to the second order phase transformation from stishovite to CaCl₂-type phase in hydrous aluminous SiO₂ also causes the depth variation of seismic scatterers in the lower mantle. The high-pressure polymorphs of aluminous SiO₂ contain a large amount of water more than 1 wt%, which can be important water carriers under lower mantle conditions.

DOI： 10.1186/s40645-024-00670-7

researchmap

Other Link： https://link.springer.com/article/10.1186/s40645-024-00670-7/fulltext.html

Elastic anomalies across the P21nm→Pnnm structural phase transition in δ-(Al,Fe)OOH Reviewed

Niccolò Satta, Giacomo Criniti, Alexander Kurnosov, Tiziana Boffa Ballaran, Takayuki Ishii, Hauke Marquardt

American Mineralogist 109 ( 11 ) 1934 - 1944 2024.11

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

Abstract

Hydrogen may be recycled into the Earth’s lower mantle by subduction and stabilized in solid solutions between phase H (MgSiO4H2), δ-AlOOH, ε-FeOOH, and SiO2 post-stishovite. In high-pressure oxyhydroxide phases, hydrogen is incorporated following the typical (OHO) sequence, adopting the asymmetric configuration O-H···O that evolves into a symmetric disordered state upon compression. Moreover, these iron-bearing aluminum oxyhydroxides [δ-(Al,Fe)OOH] present a structural phase transition from P21nm to Pnnm as pressure increases. Here, the single-crystal elasticity of the P21nm phase of δ-(Al0.97Fe0.03)OOH has been experimentally determined across the P21nm→Pnnm transition up to 7.94(2) GPa by simultaneous single-crystal X-ray diffraction (XRD) and Brillouin scattering at high pressures. The transition appears to be continuous, and it can be described with a second-, fourth-, and sixth-order terms Landau potential. Our results reveal an enhanced unit-cell volume compressibility, which is linked to an increase of the b- and a-axes linear compressibility in the P21nm phase of δ-(Al0.97Fe0.03)OOH prior to the transition. In addition, we observed the presence of elastic softening in the P21nm phase that mostly impacts the elastic stiffness coefficients c12, c22, and c23. The observed elastic anomalies cause a significant change in the pressure dependence of the adiabatic bulk modulus (KS). These results provide a better understanding of the relation between elasticity, P21nm→Pnnm structural phase transition, and hydrogen dynamics in δ-(Al0.97Fe0.03)OOH, which may be applied to other O-H···O-bearing phases.

DOI： 10.2138/am-2023-9129

researchmap

Post-spinel-type AB2O4 high-pressure phases in geochemistry and materials science

Masaki Akaogi, Takayuki Ishii, Kazunari Yamaura

Communications Chemistry 7 ( 1 ) 2024.8

Synthesis and Crystal Structure of Ilmenite-Type Silicate with Pyrope Composition

Takayuki Ishii, Ryosuke Sinmyo, Tomoo Katsura

Solids 2024.8

Melting at the base of a terrestrial magma ocean controlled by oxygen fugacity Reviewed

Yanhao Lin, Takayuki Ishii, Wim van Westrenen, Tomoo Katsura, Ho-Kwang Mao

Nature Geoscience 17 ( 8 ) 803 - 808 2024.7

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

Abstract

Heat delivered from accretionary impacts is thought to have led to extensive melting of early Earth’s silicate mantle, resulting in a deep magma ocean covering the surface. The mantle’s oxygen fugacity is thought to have increased over accretion and core formation due to increasingly oxidated impactors and lower mantle self-oxidation, but the influence of this on the solidus of deep primitive mantle materials has not been well constrained. Here we assess the effect of oxygen fugacity on conditions at the bottom of a magma ocean by experimentally determining the solidus of mantle pyrolite at pressures of 16–26 GPa at high oxygen fugacities. We find that over this pressure range, the solidus in experiments conducted under oxidizing conditions is at least 230–450 °C lower than in experiments conducted under more reducing conditions. Assuming constant magma ocean temperature, this would imply a magma ocean floor that deepens by about 60 km for each log unit increase in mantle oxygen fugacity. The strong influence of oxygen fugacity on mantle melting suggests that models of early Earth thermal evolution and geochemical models of core formation should be reassessed.

DOI： 10.1038/s41561-024-01495-1

researchmap

Other Link： https://www.nature.com/articles/s41561-024-01495-1

K- and Na-rich davemaoite inclusion in diamond is not inherited from deeply subducted oceanic crusts Reviewed

Wenqing Sun, Renbiao Tao, Jintao Zhu, Chao Wang, Takayuki Ishii, Yunxiu Li

Earth and Planetary Science Letters 637 118741 - 118741 2024.7

Inert structural transition in 4H and 6H SiC at high pressure and temperature: a Raman spectroscopy study

Shuhou Maitani, Ryosuke Sinmyo, Takayuki Ishii, Kenji Yoza

Journal of Physics Communications 8 ( 6 ) 2024.6

Hydrogen partitioning between stishovite and hydrous phase δ: implications for water cycle and distribution in the lower mantle Reviewed

Takayuki Ishii, Giacomo Criniti, Narangoo Purevjav, Tomoo Katsura, Eiji Ohtani

Progress in Earth and Planetary Science 2024.2

Temperature Dependence of H₂O Solubility in Al‐Free Stishovite Reviewed

Narangoo Purevjav, Hongzhan Fei, Takayuki Ishii, Giacomo Criniti, Yanhao Lin, Ho‐Kwang Mao, Tomoo Katsura

Geophysical Research Letters 51 ( 3 ) 2024.2

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

Abstract

The role of stishovite in transporting water in subducting slabs has been a subject of debate for several decades. Here we investigated stishovite's water solubility and its potential role in water transportation as a function of temperature from 1300 to 2100°C at 22 GPa. Under water‐saturated conditions, high‐quality, Al‐free stishovite single crystals were synthesized with multi‐anvil press, and their water contents were measured using infrared spectroscopy. The H₂O solubility in stishovite increases from 128(20) to 521(47) wt. ppm with increasing temperature from 1300 to 1700°C and decreased to 145(26) wt. ppm at 2100°C. The maximum H₂O content was about seven times larger than earlier high‐temperature multi‐anvil studies but significantly lower than recent laser‐heated diamond anvil cell and low‐temperature multi‐anvil studies. We suggest that Al‐free stishovite may not be a significant H₂O carrier in subducting slabs, at least at the topmost lower mantle corresponding to our experimental conditions.

DOI： 10.1029/2023gl104029

researchmap

Crystal chemistry and compressibility of Fe0.5Mg0.5Al0.5Si0.5O3 and FeMg0.5Si0.5O3 silicate perovskites at pressures up to 95 GPa Reviewed

Iuliia Koemets, Biao Wang, Egor Koemets, Takayuki Ishii, Zhaodong Liu, Catherine McCammon, Artem Chanyshev, Tomo Katsura, Michael Hanfland, Alexander Chumakov, Leonid Dubrovinsky

Frontiers in Chemistry 11 2023.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Frontiers Media SA

Silicate perovskite, with the mineral name bridgmanite, is the most abundant mineral in the Earth’s lower mantle. We investigated crystal structures and equations of state of two perovskite-type Fe³⁺-rich phases, FeMg_0.5Si_0.5O₃ and Fe_0.5Mg_0.5Al_0.5Si_0.5O₃, at high pressures, employing single-crystal X-ray diffraction and synchrotron Mössbauer spectroscopy. We solved their crystal structures at high pressures and found that the FeMg_0.5Si_0.5O₃ phase adopts a novel monoclinic double-perovskite structure with the space group of P21/n at pressures above 12 GPa, whereas the Fe_0.5Mg_0.5Al_0.5Si_0.5O₃ phase adopts an orthorhombic perovskite structure with the space group of Pnma at pressures above 8 GPa. The pressure induces an iron spin transition for Fe³⁺ in a (Fe_0.7,Mg_0.3)O₆ octahedral site of the FeMg_0.5Si_0.5O₃ phase at pressures higher than 40 GPa. No iron spin transition was observed for the Fe_0.5Mg_0.5Al_0.5Si_0.5O₃ phase as all Fe³⁺ ions are located in bicapped prism sites, which have larger volumes than an octahedral site of (Al_0.5,Si_0.5)O₆.

DOI： 10.3389/fchem.2023.1258389

researchmap

Structure and compressibility of Fe-bearing Al-phase D Reviewed

Giacomo Criniti, Takayuki Ishii, Alexander Kurnosov, Konstantin Glazyrin, Rachel J. Husband, Tiziana Boffa Ballaran

American Mineralogist 108 ( 9 ) 1764 - 1772 2023.9

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

Abstract

Due to its large thermal stability, Al-phase D, the (Al,Fe3+)2SiO6H2 member of the dense hydrous magnesium silicate (DHMS) phase D, may survive along hot subduction geotherms or even at ambient mantle temperatures in the Earth’s transition zone and lower mantle, therefore potentially playing a major role as a water reservoir and carrier in the Earth’s interior. We have investigated the crystal structure and high-pressure behavior of Fe-bearing Al-phase D with a composition of Al1.53(2)Fe0.22(1) Si0.86(1)O6H3.33(9) by means of single-crystal X-ray diffraction. While the structure of pure Al-phase D (Al2SiO6H2) has space group P63/mcm and consists of equally populated and half-occupied (Al,Si)O6 octahedra, Fe-incorporation in Al-phase D seems to induce partial ordering of the cations over the octahedral sites, resulting in a change of the space group from P63/mcm to P6322 and in well-resolved diffuse scattering streaks observed in X-ray images. The evolution of the unit-cell volume of Fe-bearing Al-phase D between room pressure and 38 GPa, determined by means of synchrotron X-ray diffraction in a diamond anvil cell, is well described by a third-order Birch-Murnaghan equation of state having an isothermal bulk modulus KT0 = 166.3(15) GPa and first pressure derivative KT0′ = 4.46(12). Above 38 GPa, a change in the compression behavior is observed, likely related to the high-to-low spin crossover of octahedrally coordinated Fe3+. The evolution of the unit-cell volume across the spin crossover was modeled using a recently proposed formalism based on crystal-field theory, which shows that the spin crossover region extends from approximately 30 to 65 GPa. Given the absence of abrupt changes in the compression mechanism of Fe-bearing Al-phase D before the spin crossover, we show that the strength of H-bonds and likely their symmetrization do not greatly affect the elastic properties of phase D solid solutions, independently of their compositions.

DOI： 10.2138/am-2022-8559

researchmap

　 PREV - NEXT 　

< Ishii Takayuki >

Papers - Ishii Takayuki