A5005567936- High-pressure geophysics and materials
- Diamond and Carbon-based Materials Research
- Geological and Geochemical Analysis
- Crystal Structures and Properties
- Metal and Thin Film Mechanics
- Boron and Carbon Nanomaterials Research
- Force Microscopy Techniques and Applications
- earthquake and tectonic studies
- Advanced materials and composites
- Magnetic and transport properties of perovskites and related materials
- Glass properties and applications
- Rare-earth and actinide compounds
- Electronic and Structural Properties of Oxides
- Nuclear materials and radiation effects
- Solid-state spectroscopy and crystallography
- Astro and Planetary Science
- Advanced Surface Polishing Techniques
- Iron-based superconductors research
- Magnesium Alloys: Properties and Applications
- ZnO doping and properties
- X-ray Diffraction in Crystallography
- Metallurgical Processes and Thermodynamics
- Advanced Materials Characterization Techniques
- Advanced Condensed Matter Physics
- Advanced ceramic materials synthesis
Ehime University
2016-2025
Matsuyama University
2017-2021
Dynamic Research (United States)
2015-2020
Warsaw University of Technology
2016
Yanshan University
2012
Yale University
2003-2008
Okayama University
1999-2004
Hokkaido University
1998-1999
University of Tsukuba
1998
Tohoku University
1998
Phase relations of the olivine‐wadsleyite transition in system (Mg,Fe) 2 SiO 4 have been determined at 1600 and 1900 K using quench method a Kawai‐type high‐pressure apparatus. Pressure was precision better than 0.2 GPa situ X‐ray diffraction with MgO as pressure standard. The pressures end‐member Mg are estimated to be 14.2 15.4 K, respectively. Partition coefficients for Fe between olivine wadsleyite 0.51 0.61 K. By comparing depth discontinuity pressure, temperature 410 km is 1760 ± 45...
Phase transitions and the chemical composition of minerals in Earth's interior influence geophysical interpretations its deep structure dynamics. A pressure-induced spin transition olivine has been suggested to iron partitioning depletion, resulting a distinct layered lower mantle. For more realistic mantle (pyrolite), we observed considerable change iron-magnesium partition coefficient at about 40 gigapascals that is explained by much pressures. However, only small depletion major...
In experiments at 13.5 gigapascals and 1030 degreesC, the growth rate of wadsleyite, which forms from transformation olivine, was substantially enhanced by presence water. Wadsleyite had a low dislocation density subgrain boundaries in wet runs. Water recovery wadsleyite therefore caused inelastic relaxation localized pressure drop associated with transformation, resulting an increase These results imply that even small amount water 0. 05 weight percent can weaken mantle.
X ray diffraction and transmission electron microscopy on laser‐heated diamond cell samples show that with increasing pressure MgAl 2 O 4 spinel transforms first to Al 3 corundum + MgO periclase, then the CaFe ‐structured phase, finally a new phase having CaTi structure above ∼40 GPa. The structures are closely related have almost same densities bulk moduli. Transformation from would be expected take place in oceanic crust is subducted deep into lower mantle.
Abstract Transparent ceramics are important for scientific and industrial applications because of the superior optical mechanical properties. It has been suggested that transparency strength substantially enhanced if transparent with nano-crystals available. However, synthesis highly nano-crystalline difficult using conventional sintering techniques at relatively low pressures. Here we show direct conversion from bulk glass starting material in mutianvil high-pressure apparatus leads to...
Hydrogen bond symmetrisation is the phenomenon where a hydrogen atom located at centre of bond. Theoretical studies predict that bonds in ice VII eventually undergo upon increasing pressure, involving nuclear quantum effect with significant isotope and drastic changes elastic properties through several intermediate states varying distribution. Despite numerous experimental conducted, location hence transition pressures reported up to date remain inconsistent. Here we report atomic...
Elastic wave velocities of synthetic polycrystalline Mg3Al2(SiO4)3 garnet have been successfully measured to 20 GPa and temperatures up 1700 K by ultrasonic interferometry combined with energy-dispersive synchrotron x-ray diffraction in a Kawai-type multi-anvil apparatus. Compressional (Vp) shear (Vs) as well the adiabatic bulk (Ks) (G) moduli exhibit monotonic increase increasing pressure decrease temperature, respectively. Two-dimensional (P-T) linear fittings present data yield following...
Crystal structures and phase transitions of enstatite (MgSiO 3 ) were studied by in situ X-ray diffraction experiments using synchrotron radiation a multi-anvil high-pressure apparatus at pressures to 12 GPa temperatures 1473 K. Low clinoenstatite with space group P2 1 /c transforms C2/c high temperatures, accompanied volume reduction about 2.5%.The β angle this ranges from 101.4° 101.7°, shows almost no variation pressure temperature, is 8° smaller than that the high-temperature previously...
The phase relations in boron have been investigated at high pressure and temperature using a multianvil apparatus, the quenched sample has analyzed by x-ray diffraction, Raman spectra, transmission electron microscopy. We demonstrate that $\ensuremath{\gamma}$-B${}_{28}$ can be synthesized over wide range, $\ensuremath{\alpha}$-tetragonal B${}_{50}$ (T-B${}_{50}$) is obtained higher temperatures similar pressures. boundary of $\ensuremath{\beta}$-B${}_{106}$,...
We investigated the pressure effects of a superconductivity on thin films Sn. Elemental superconductor Sn with body-centered tetragonal structure, $\beta$-Sn, exhibits below superconducting transition temperature ($T_{\rm c}=3.72$ K) at ambient pressure. $T_{\rm c}$ increases lowering dimension such as in film and nanowire growth, or by high-pressure application. For films, slight increase up to approximately 4 K compared bulk value, attributable crystalline size lattice disorder. By...
A large-strain, torsional deformation apparatus has been developed based on diamond anvil cells at high pressures, up to 135 GPa with a help of hard nano-polycrystalline anvils. These pressure conditions correspond the base Earth’s mantle. An X-ray laminography technique is introduced for high-pressure in situ 3D observations strain markers. The this study introduces possibility rheological measurements deep Earth materials under ultrahigh-pressure conditions.
Stability relations of iron have been studied by means in situ X‐ray observations using an eight cubic anvil system (Kawai‐type apparatus) equipped with sintered diamond (SD), order to explore the stability β‐iron. By observing forward and reverse transitions, it has confirmed that ε‐iron directly transforms into γ phase up ca. 44 GPa 2100 K, excluding β phase. The constrained ε‐γ boundary is expressed equation T (K) = 25 × P (GPa) + 540.
The effect of chemical environment on the hydrogen-related defect chemistry in wadsleyite was investigated using Fourier-transform infrared (FTIR) spectroscopy. Samples were annealed at P = 14-16 GPa and T 1230-1973 K Kawai-type multi-anvil apparatus. oxygen fugacity (fO₂) three metal-oxide buffers (Mo-MoO2, Ni-NiO, Re-ReO2). water (fH₂₂O) studied two different capsule assemblies (“nominally dry” “dry” assemblies). A range total OH concentration (COH,Total) wadslyeites varies between <50...