Kazuhiko Otsuka

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Sheardeformationexperimentsondryhot-pressedpolycrystallineSanCarlosolivinehavebeenconducted at 4.9–9.6GPa, 1300–1870K and strain rates of 0.6–7.4×10−5 s−1 using a rotational Drickamer apparatus (RDA) at a synchrotron facility. The stress was measured from the orientational dependence of lattice spacing for the (130), (1 31), (1 12), (1 22), (1 40) and (241)(More)
The core-mantle boundary of Earth is a region where iron-rich liquids interact with oxides and silicates in the mantle. Iron enrichment may occur at the bottom of the mantle, leading to low seismic-wave velocities and high electrical conductivity, but plausible physical processes of iron enrichment have not been suggested. Diffusion-controlled iron(More)
We report the results of plastic deformation experiments on polycrystalline wadsleyite and ringwoodite performed at 15–23 GPa and 1300–2100 K conducted using the rotational Drickamer apparatus (RDA). Wadsleyite was synthesized from fine-grained ( 2 mm) San Carlos olivine in a Kawai-type multianvil apparatus; the average grain size of the resulting(More)
We investigated the ferric iron (Fe3þ) concentration in (Mg,Fe)O ferropericlase using the flank method applied to Mg–Fe interdiffusion couples of ferropericlase. Diffusion couples with Mg/(MgþFe) in the range 0.44 to 1 were annealed at temperatures of 1673–1873 K and pressures of 5–24 GPa over a wide range of oxygen fugacities. Oxygen fugacity was(More)
[1] Shear deformation experiments on polycrystalline wadsleyite (water content, ∼200– 2200 H/10 Si) have been conducted at 14.4–17.0 GPa, 1690–2100 K, and strain rates of 2.6–16 × 10 s using a rotational Drickamer apparatus (RDA) at a synchrotron facility. The stress was measured from the orientation dependence of lattice spacing for the (013), (211),(More)
A new method is developed to control water fugacity at a fixed pressure and temperature. We use two divariant phase assemblages (clinohumite–periclase–forsterite and brucite–periclase) in the MgO– SiO2–H2O system and the chemical reactions among co-existing phases buffer the water fugacity. In order to avoid a reaction between the water fugacity buffer and(More)
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