担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MDPI AG  

The structure of hydrous amorphous SiO2 is fundamental in order to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO2 glass with 13 wt.% D2O was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into two phases: a major phase rich in SiO2 and a minor phase rich in D2O molecules distributed as small domains with dimensions of less than 100 Å. Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO2 glass by disruption of SiO4 linkage due to the formation of Si–OD deuterioxyl, while the response of its structure to pressure is almost the same as that of the anhydrous SiO2 glass. Most of D2O molecules are in the small domains and hardly penetrate into the void space in the ring consisting of SiO4 tetrahedra.

DOI： 10.3390/min10010084

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/2019JE005936

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1016/j.crte.2018.04.005

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER  

The phase relationships of the Fe-Ni-S system at 15 GPa were studied by high pressure quench experiments. The stability fields of (Fe,Ni)(3)S and (Fe,Ni)(3)S-2 and the melting relationships of the Fe-Ni-S system were determined as a function of Ni content. The (Fe,Ni)(3)S solid solution is stable in the composition of Ni/(Fe + Ni) > 0.7 and melts incongruently into an Fe-Ni alloy + liquid. The (Fe,Ni)(3)S-2 makes a complete solid solution and melts incongruently into (Fe,Ni)S + liquid, whose structure was determined to show Cmcm-orthorhombic symmetry by in situ synchrotron X-ray diffraction experiments. The eutectic contains about 30 at.% of S, and its temperature decreases with increasing Ni content with a rate of similar to 5 K/at.% from 1175 K. The density of the Fe-FeS eutectic composition (Fe70S30) liquid is evaluated to be 6.93 +/- 0.08 g/cm(3) at 15 GPa and 1200 K based on the Clausius-Clapeyron relations and densities of subsolidus phases. The Fe-Ni-S liquids are a primary sulfur-bearing phase in the deep mantle with a reducing condition (250-660 km depth), and they would play a significant role in the carbon cycle as a carbon host as well as in the generation of diamond.

DOI： 10.1016/j.pepi.2018.01.007

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担当区分：責任著者   記述言語：英語  

DOI： 10.18957/rr.6.2.208

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Carbon is one of the possible light elements in the cores of the terrestrial planets. The P wave velocity (V-P) and density (rho) are important factors for estimating the chemical composition and physical properties of the core. We simultaneously measured the V-P and rho of Fe-3.5 wt % C up to 3.4 GPa and 1850 K by using ultrasonic pulse-echo method and X-ray absorption methods. The V-P of liquid Fe-3.5 wt % C decreased linearly with increasing temperature at constant pressure. The addition of carbon decreased the V-P of liquid Fe by about 2% at 3 GPa and 1700 K and decreased the Fe density by about 2% at 2 GPa and 1700 K. The bulk modulus of liquid Fe-C and its pressure (P) and temperature (T) effects were precisely determined from directly measured rho and V-P data to be K-0,K-1700 K = 83.9 GPa, dK(T)/dP = 5.9(2), and dK(T)/dT = -0.063(8) GPa/K. The addition of carbon did not affect the isothermal bulk modulus (K-T) of liquid Fe, but it decreased the dK/dT of liquid Fe. In the rho-V-P relationship, V-P increases linearly with rho and can be approximated as V-P (m/s) = -6786(506) + 1537(71) x rho (g/cm(3)), suggesting that Birch's law is valid for liquid Fe-C at the present P-T conditions. Our results imply that at the conditions of the lunar core, the elastic properties of an Fe-C core are more affected by temperature than those of Fe-S core.

DOI： 10.1002/2016JB012968

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER  

The sound velocity (V (P)) of liquid Fe-10 wt% Ni and Fe-10 wt% Ni-4 wt% C up to 6.6 GPa was studied using the ultrasonic pulse-echo method combined with synchrotron X-ray techniques. The obtained V (P) of liquid Fe-Ni is insensitive to temperature, whereas that of liquid Fe-Ni-C tends to decrease with increasing temperature. The V (P) values of both liquid Fe-Ni and Fe-Ni-C increase with pressure. Alloying with 10 wt% of Ni slightly reduces the V (P) of liquid Fe, whereas alloying with C is likely to increase the V (P). However, a difference in V (P) between liquid Fe-Ni and Fe-Ni-C becomes to be smaller at higher temperature. By fitting the measured V (P) data with the Murnaghan equation of state, the adiabatic bulk modulus (K (S0)) and its pressure derivative (K (S) (') ) were obtained to be K (S0) = 103 GPa and K (S) (') = 5.7 for liquid Fe-Ni and K (S0) = 110 GPa and K (S) (') = 7.6 for liquid Fe-Ni-C. The calculated density of liquid Fe-Ni-C using the obtained elastic parameters was consistent with the density values measured directly using the X-ray computed tomography technique. In the relation between the density (rho) and sound velocity (V (P)) at 5 GPa (the lunar core condition), it was found that the effect of alloying Fe with Ni was that rho increased mildly and V (P) decreased, whereas the effect of C dissolution was to decrease rho but increase V (P). In contrast, alloying with S significantly reduces both rho and V (P). Therefore, the effects of light elements (C and S) and Ni on the rho and V (P) of liquid Fe are quite different under the lunar core conditions, providing a clue to constrain the light element in the lunar core by comparing with lunar seismic data.

DOI： 10.1007/s00269-015-0789-y

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：NATURE PUBLISHING GROUP  

The boundary between Earth's rigid lithosphere and the underlying, ductile asthenosphere is marked by a distinct seismic discontinuity(1). A decrease in seismic-wave velocity and increase in attenuation at this boundary is thought to be caused by partial melt(2). The density and viscosity of basaltic magma, linked to the atomic structure(3,4), control the process of melt separation from the surrounding mantle rocks(5-9). Here we use high-pressure and high-temperature experiments and in situ X-ray analysis to assess the properties of basaltic magmas under pressures of up to 5.5 GPa. We find that the magmas rapidly become denser with increasing pressure and show a viscosity minimum near 4 GPa. Magma mobility-the ratio of the melt-solid density contrast to the magma viscosity-exhibits a peak at pressures corresponding to depths of 120150 km, within the asthenosphere, up to an order of magnitude greater than pressures corresponding to the deeper mantle and shallower lithosphere. Melts are therefore expected to rapidly migrate out of the asthenosphere. The diminishing mobility of magma in Earth's asthenosphere as the melts ascend could lead to excessive melt accumulation at depths of 80-100 km, at the lithosphere-asthenosphere boundary. We conclude that the observed seismic discontinuity at the lithosphere-asthenosphere boundary records this accumulation of melt.

DOI： 10.1038/NGEO1982

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER  

Carbon is a plausible light element candidate in the Earth's outer core. We measured the density of liquid Fe-3.5 wt% C up to 6.8 GPa and 2200 K using an X-ray absorption method. The compression curve of liquid Fe-C was fitted using the third-order Birch-Murnaghan equation of state. The bulk modulus and its pressure derivative are K-0.1500K = 55.3 +/- 2.5 GPa and (dK(o)/dP)(T) = 5.2 +/- 1.5, and the thermal expansion coefficient is alpha = 0.86 +/- 0.04 x 10(-4) K-1. The Fe-C density abruptly increases at pressures between 4.3 and 5.5 GPa in the range of present temperatures. Compared with the results of previous density measurements of liquid Fe-C, the effect of carbon on the density of liquid Fe shows a nonideal mixing behavior. The abrupt density increase and nonideal mixing behavior are important factors in determining the light element content in the Earth's core. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.pepi.2013.08.003

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The interfacial tension of Fe-Si liquid was measured using in situ X-ray radiography at high pressure and temperatures using the sessile drop method. The interfacial tension of Fe-Si liquid decreases (from 665 to 407 mN/m) with increasing temperature (1673-2173 K) at 1.5 GPa. The interfacial tension also decreases gradually with increasing Si content (0-25 at%), suggesting that Si behaves as a "moderately" surface-active element. Comparing the effects of different light elements on the interfacial tension of liquid iron, the most effective elements for reducing the interfacial tension lie in the order S > Si > P. although P has almost no effect. The droplet size of emulsified Fe-alloys in a magma ocean are estimated to be larger for Fe-Si and Fe-P liquids and smaller for Fe-S (S > 10 at%) liquid compared with that for pure Fe liquid. Therefore, if droplets in a magma ocean are enriched in S, chemical equilibrium between droplets and silicate melt is established faster in the magma ocean compared to Fe, Fe-Si and Fe-P liquids. (c) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.pepi.2012.05.002

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We investigated the pressure-induced structural changes in hydrous forsterite and enstatite melts using in situ synchrotron X-ray diffraction. Diffraction data was collected up to 6.9 GPa at superliquidus temperatures. At pressures below 3 GPa, the first sharp diffraction peak (FSDP), which reflects the silicate network ordering in the silicate melts that consist of (center dot center dot center dot)-Si-O-Si-(center dot center dot center dot) linkages, is shifted notably toward higher Q (scattering vector [angstrom(-1)]) in both melt compositions. This observation indicates that water has a depolymerizing effect on the silicate network below 3 GPa, which means that (center dot center dot center dot)-Si-O-Si-(center dot center dot center dot) linkages are partially disrupted by hydroxyl species (Si-OH units). In contrast, the peaks move to lower Qat pressures above 3 GPa in spite of the compression, which indicates lengthening of the silicate network ordering (i.e., polymerization of silicate network). This observation indicates that water changes to have a polymerizing effect on the silicate network above 3 GPa by a new free hydroxyl group such as Mg-OH, which was previously proposed in the study on hydrous silicate glasses structure. In fact, the structural changes in the present study are more pronounced in the hydrous Mg(2)SiO(4) melt, suggesting that the MgO component has an important influence on the polymerization of hydrous melt structure at 3-5 GPa. The present structural change, re-polymerization at high pressure, in hydrous silicate melt can influence the viscosity. Such a relatively high-viscosity hydrous magma may be able to stay (or be decreased in the rising velocity) at a depth of 100-180 km, which can enhance the decrease in a seismological wave velocity in the Earth's asthenosphere as proposed in previous seismological observations. (C) 2011 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2011.05.036

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MINERALOGICAL SOC AMER  

The density of liquid iron sulfide (FeS) was measured up to 3.8 GPa and 1800 K using an X-ray absorption method. The compression curve of liquid FeS was fitted using the Vinet equation of state. The isothermal bulk modulus and its temperature and pressure derivatives were determined using a nonlinear least-squares fit. The parameter sets determined were: K(0T) = 2.5 +/- 0.3 GPa at T = 1500 K, (dK(0)/dT)(P) = 0.0036 +/- 0.0003 GPa/K, and (dK(0)/dP)(T) = 24 +/- 2. These results suggest that liquid FeS is more compressible than Fe-rich liquid Fe-S.

DOI： 10.2138/am.2011.3616

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MINERALOGICAL SOC AMER  

The density of carbonated peridotite magma was measured up to 3.8 GPa and 2100 K using an X-ray absorption method. A fit of the pressure-density-temperature data to the high-temperature Birch-Murnaghan equation of state yielded the isothermal bulk modulus, K(T0) = 22.9 +/- 1.4 GPa, its pressure derivative, K'(0) = 7.4 +/- 1.4, and the temperature derivative of the bulk modulus (partial derivative K(T)/partial derivative T)(P) = -0.006 +/- 0.002 GPa/K at 1800 K. The bulk modulus of carbonated peridotite magma is larger than that of hydrous peridotite magma. The partial molar volume of CO, in magma under high pressure and temperature conditions was calculated and fit using the Vinet equation of state. The isothermal bulk modulus was K(T0) = 8.1 +/- 1.7GPa, and its pressure derivative was K'0 = 7.2 +/- 2.0 at 2000 K. Our results show that the partial molar volume of CO(2) is less compressible than that of H(2)O, suggesting that, on an equal molar basis, CO(2) is more effective than H(2)O in reducing peridotite melt density at high pressure.

DOI： 10.2138/am.2011.3577

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担当区分：筆頭著者,　責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MINERALOGICAL SOC AMER  

We found a new nickel sulfide that is isostructural with Fe3S. The synthesized nickel sulfide is a non-stoichiometric compound with a Ni deficiency and its composition is Ni2.90 +/- 0.5S. In situ synchrotron X-ray observations indicate that Ni3-xS forms above 5.1 GPa and melts incongruently into Ni+liquid up to 10 GPa. The bulk modulus of Ni3-xS at 300 K was determined to be 140 +/- 2 GPa with a fixed K' = 4 by static compression with a liquid pressure medium. The eutectic point of the Ni-NiS system lies between Ni3S and Ni3S2 up to 10 GPa and its composition changes from Ni66.6S33.4 at 0.1 MPa to Ni70.7S29.3 at 10 GPa. The eutectic melting temperature of the Ni-NiS system decreases to 5.1 GPa and 720 K as the pressure increases where Ni and alpha-Ni3S2 are the eutectic solids. On the other hand, the eutectic melting temperature increases with a positive slope above 5.1 GPa where Ni3S+alpha-Ni3S2 is stable under subsolidus conditions. Intermediate compounds appear at a lower pressure in the Ni-NiS system than that for the Fe-FeS system. Ni3S2 is stable at atmospheric pressure and Ni3S forms at 5.1 GPa, whereas Fe3S2 and Fe3S form at 14 and 20 GPa, respectively. The addition of Ni coomplicates the melting relationship in the Fe-FeS system at high pressure because of the wider stability field of Ni3S. The low-melting temperature of the Fe-Ni-S system plays an important role in the percolative core-formation of planetesimals during planetary accretion.

DOI： 10.2138/am.2011.3578

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The density of the Apollo 14 black glass melt, which has the highest TiO(2) content of pristine mare glasses, was measured to 4.8 GPa and 2100 K using an X-ray absorption method. A fit of the pressure-density-temperature data to the high-temperature Birch-Murnaghan equation of state yielded the isothermal bulk modulus K(T0) = 9.0 +/- 1.2 GPa, its pressure derivative K(0)' = 16.0 +/- 3.4, and the temperature derivative of the bulk modulus (partial derivative K(T)/partial derivative T)(P) = -0.0030 +/- 0.0008 GPa/K at 1700 K. The high-Ti basalt magma is less dense than the lunar mantle below about 1.0 GPa. Therefore, the high-Ti basalt magma produced in the hybridized source (100-200 km) can ascend to the lunar surface. The basalt formed at the higher pressure could not ascend but move downwards, and solidify in the lunar mantle. The solidified high-Ti basalt components can create chemical heterogeneities in the lunar mantle and can cause the low-velocity anomalies observed seismologically. (C) 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2010.09.007

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MINERALOGICAL SOC AMER  

The density of a peridotite magma was measured up to 2.5 GPa and 2300 K using an X-ray absorption method. The method allowed measurement of the density of a peridotite melt under seven different conditions and clarified the pressure and temperature dependence of the density. A fit of the pressure-density-temperature data to the high-temperature Birch-Mumaghan equation of state yielded the isothermal bulk modulus, K(T0) = 24.0 +/- 1.3 GPa. its pressure derivative, K(0)' = 7.3 +/- 0.8, and the derivative of bulk modulus (partial derivative K(T)/partial derivative T)(P) = -0.0027 +/- 0.0017 GPa/K at 2100 K. The large bulk modulus and its pressure derivative of the peridotite melt compared with that of basaltic melt is consistent with previous results from sink-float experiments.

DOI： 10.2138/am.2010.3143

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IOP PUBLISHING LTD  

A new high-pressure apparatus has been developed for studies of synchrotron radiation-based X-ray microtomography at SPring-8 of Japan. The high pressure tomography apparatus at SPring-8 is a compact hydraulic press with a 0.8 MN capacity and is equipped with an opposed anvil device. It has two wide windows for X-ray access with a 160-degree opening in the equatorial plane to the compression axis. Radiographs are acquired over 180 degree rotation for reconstruction of 3D image, in which some shadows occur, because the press frame blocks a 20-degree angular region. 3D tomography image computed from radiographs obtained using the high pressure tomography apparatus has a reasonably good quality enough to measure physical properties of materials.

DOI： 10.1088/1742-6596/215/1/012026

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The density of hydrous peridotite magma containing 5 wt.% H(2)O Was measured at pressures and temperatures up to 4.3 GPa and 2073 K, respectively, using the X-ray absorption method. A fit of pressure-density-temperature data to the high-temperature Birch-Murnaghan equation of state yields isothermal bulk modulus K(T) = 8.8 +/- 1.9 GPa. its pressure derivative K' = 9.9 +/- 3.6 and the temperature derivative of the bulk modulus (partial derivative K(T)/partial derivative T)(p) = -0.0022 +/- 0.0015 GPa/K at 1773 K. The small bulk modulus of the hydrous peridotite magma compared with that of the dry peridotite magma reflects the effect of water, which is more compressible than the silicate melt. The partial molar volume of H(2)O in magma under high pressure conditions was calculated and fitted using the Vinet equation of state. The isothermal bulk modulus was K(T) = 2.4 +/- 1.0 GPa, and its pressure derivative was K' = 5.7 +/- 1.5 at 1973 K. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.epsl.2009.07.030

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Interfacial tension is one of the most important properties of the liquid iron alloy that controls the core formation process in the early history of the Earth and planets. In this study, we made high-pressure X-ray radiography and micro-tomography measurements to determine the interfacial tension between liquid iron alloys and silicate melt using the sessile drop method. The measured interfacial tension of liquid Fe-S decreased significantly (802-112 mN/m) with increasing sulphur content (0-40 at%) at 1.5 GPa. In contrast, the phosphorus content of Fe had an almost negligible effect on the interfacial tension of liquid iron. These tendencies in the effects of light elements are consistent with those measured at ambient pressure. Our results suggest that the effect of sulphur content on the interfacial tension of liquid Fe-S (690 mN/m reduction with the addition of 40 at% S) is large compared with the effect of temperature (similar to 273 mN/m reduction with an increase of 200 K). The three-dimensional structure of liquid Fe-S was obtained at similar to 2 GPa and 1373-1873 K with a high-pressure tomography technique. The Fe-S droplet was quite homogeneous when evaluated in a slice of the three-dimensional image. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.pepi.2009.01.004

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

High-pressure, high-temperature X-ray tomography experiments have been carried out using a large volume toroidal cell, which is optimized for interfacial tension measurements. A wide anvil gap, which corresponds to a field of view in the radiography imaging, was successively maintained to high pressures and temperatures using a composite plastic gasket. Obtained interfacial tensions of Ni-S liquid against Na, K-disilicate melt, were 414 and 336 mN/m at 1253 and 1293 K, respectively. Three-dimensional tomo-graphy images revealed that the sample had an irregular shape at the early stage of melting, suggesting either non-equilibrium in sample texture and force balance or partial melting of surrounding silicate. This information cannot always be obtained from two-dimensional radiographic imaging techniques. Therefore, a three-dimensional tomography measurement is appropriate for the precise interfacial measurements.

DOI： 10.1080/08957950802208902

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

Structure of a hydrous silicate melt with a forsterite-enstatite-H2O composition was investigated by in-situ X-ray diffraction with synchrotron radiation. The high temperature hydrous melt was successfully enclosed in a single-crystal diamond capsule under high pressure, up to 6.5 GPa. Results showed that the first sharp diffraction peak (FSDP), which reflects the intermediate-range structure of the complex melt, shifted drastically toward higher Q ( scattering vector [angstrom(-1)]) at pressure below 2.2 GPa. This observation indicates that the silicate network in the melt was depolymerized by the influence of water molecules and partly replaced by Si-OH units under those high-pressure conditions. In contrast, between 3 - 5 GPa, such a peak shift was not clearly detected, suggesting that the lengthening of the intermediate-range ordering of ...-Si-O-Si-... linkage (i.e., polymerization of silicate network) occurred.

DOI： 10.1029/2006GL028823

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記述言語：英語   出版者・発行元：Elsevier  

This chapter summarizes the techniques for the viscosity and density measurements of silicate melts and glasses at high pressure and temperature by using the X-ray radiography and absorption techniques in the third generation synchrotron radiation facility, SPring-8, Japan. The falling sphere method using in situ X-ray radiography makes it possible to measure the viscosity of silicate melts to pressures above 6 GPa at high temperature. The details of the experimental technique of the viscosity measurement, and the results for some silicate melts such as albite and diopside-jadeite melts are discussed in detail. X-ray absorption method is applied to measure the density of silicate glasses such as basaltic glass and iron sodium disilicate glass up to 5 GPa at high temperature. A diamond capsule that is not reactive with the glasses is used for the density measurement of the glasses. The present density measurement of the glasses indicates that this method is useful for measurement of the density of silicate melts at high pressure and temperature. © 2005 Copyright © 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/b978-044451979-5.50012-0

DOI： 10.1016/B978-044451979-5.50012-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

In situ X-ray diffraction experiments on Fes up to 22 GPa and 1600 K were carried out using large volume multianvil apparatus, combined with synchrotron radiation at SPring-8. We investigated phase stability relationships of Fes and determined the straight phase boundaries between Fes III (monoclinic phase) and Fes IV (hexagonal phase) to be T (K) = 20P (GPa) + 170 and between Fes IV and Fes V (NiAs-type phase) to be T (K) = 39.6 P (GPa) + 450. We also found anomalous behavior in the c/a ratio, thermal expansion, and isothermal compression of FeS V as well as FeS IV, in the pressure range 4-12 GPa. These anomalies in Fes can be attributed to the spin-pairing transition of Fe, and divides FeS IV and FeS V into the high-spin low-pressure phase (LPP) and the possibly low-spin high-pressure phase (HPP). In order to investigate the internal structure of Mars, we evaluated the equations of state for Fes IV (HPP) and Fes V (HPP). A least square fit to the experimental data yielded K(0T) = 62.5 +/- 0.9 GPa at T = 600 K and (dK(0)/dT) p = -0.0208 +/- 0.0028 GPa/K for Fes IV (HPP), and K(0T) = 54.3 +/- 1.0 GPa at T = 1000 K and (dK(0)/dT) = -0.0117 +/- 0.0015 GPa/K for Fes V (HPP) with fixed K' = 4. Thermal expansion coefficients were alpha = 7.16 x 10(-5) + 6.08 x 10(-8) T for FeS IV (HPP) and alpha = 10.42 x 10(-5) for Fes V (HIPP), respectively. Using these equations of state, we examined the internal structure of Mars that has a model mantle composition [Meteoritics 20 (1985) 367] and Fe-FeS core. Our models show that an Mg-silicate perovskite-rich lower mantle is stable only with the Fe-rich core having less than 20 wt.% sulfur. The polar moment of inertia factor C derived from Mars Pathfinder data [Science 278 (1997) 1749] is consistent with any compositions between Fe and Fes for the Martian core, but it excludes the presence of a crust thicker than 100 km. (C) 2004 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.pepi.2003.12.015

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IOP PUBLISHING LTD  

The viscosity of liquid sulfur up to 9.7 GPa and 1067 K was measured using the in situ x-ray radiography falling sphere method. The viscosity coefficients were found to range from 0.11 to 0.69 Pa s, and decreased continuously with increasing pressure under approximately constant homologous temperature conditions. The observed viscosity variation suggests that a gradual structural change occurs in liquid sulfur with pressure up to 10 GPa. The L-L' transition in liquid sulfur proposed by Brazhkin et al (1991 Phys. Lett. A 154 413) from thermobaric measurements has not been confirmed by the present viscometry.

DOI： 10.1088/0953-8984/16/10/003

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The phase boundary of the post-spinel transition in Mg2SiO4 was re-investigated by means of high P-T in situ X-ray diffractometry with a gold pressure marker in a Kawai-type apparatus. Rapid and continuous temperature changes were conducted to initiate dissociation of spinel, which tends to be inert after long annealing. Isothermal decompression at high temperature was conducted to form spinel from perovskite plus periclase. The phase boundary is located at ca. 22 GPa in the temperature range from 1550 to 2100 K, which is 1-1.5 GPa lower than the 660 km discontinuity. This discrepancy might be explained in terms of the pressure effect of thermocouple emf and inaccurate equation of state (EOS) for the pressure maker. The transition is found to be less sensitive to temperature than reported previously, with a Clapeyron slope ranging from -2 to -0.4 MPa/K. This small Clapeyron slope implies that the post-spinel transition would not be an effective barrier to mantle convection. (C) 2003 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0031-9201(03)00019-0

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掲載種別：研究論文（学術雑誌）  

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掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：TAYLOR & FRANCIS LTD  

Phase relationships for FeS polymorph have been studied at the pressure of 16-20 GPa and temperature of 300-1350 K by in situ X-ray observation using a large volume high-pressure apparatus and a synchrotron radiation. Contrary to Fei's prediction [1], we found the stability field of NiAs-type phase of FeS extending at least to 18 GPa. Results of in situ X-ray observation correspond with the NiAs-hexagonal phase boundary determined by Kusaba et al. [2,3], Assuming the straight NiAs-hexagonal phase boundary, we estimate that the NiAs-hexagonal-liquid triple junction is located at 39.5 GPa and 2300 K.

DOI： 10.1080/08957950290006866

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

[1] The in situ viscosity measurements of the pure molten Fe under high pressures were made by falling sphere X-ray radiography method. Viscosity coefficients at about 2000 K were 15-24 mPa s at 2.7-5.0 GPa, and 4-9 mPa s at 5.0-7.0 GPa. Drastic decrease was found at around 5 GPa, at which stable solid phase below the melting temperatures change from delta (bcc) to gamma (fcc) phases. The observation indicates the possibility that the structural change in the molten Fe occurs in a narrow pressure interval (1 GPa) at the similar condition with the phase transformation in the solid.

DOI： 10.1029/2001GL014321

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

Mechanisms and kinetics of the post-spinel transformation in Mg2SiO4 were examined at 22.7-28.2 GPa and 860-1200degreesC by in situ X-ray diffraction experiments using synchrotron radiation combined with microstructural observations of the recovered samples. The post-spinel phases nucleated on spinel grain boundaries and grew with a lamellar texture. Under large overpressure conditions, reaction rims were formed along spinet grain boundaries at the initial stage of the transformation, whereas under small overpressure conditions, the transformation proceeded without formation of reaction rims. Mg2SiO4 spinel metastably dissociated into MgSiO3 ilmenite and periclase, and stishovite and periclase as intermediate steps in the transformation into the stable assemblage of MgSiO3 perovskite and periclase. Topotactic relationships were found in the transformation from spinet into ilmenite and periclase. Kinetic parameters in the Avrami rate equation, time taken to 10% completion, and the growth rate were estimated by analysis of the kinetic data obtained by in situ X-ray observations. The empirical activation energy for 10% transformation decreases with increasing pressure because the activation energy for nucleation becomes smaller at larger overpressure conditions. Extrapolations of the 10% transformation to similar to700degreesC, which is the lowest temperature expected for the cold slabs at similar to700 km depth, suggest that overpressure of more than similar to1 GPa is needed for the transformation. Because the growth rate is estimated to be large even at low-temperatures of similar to700degreesC and overpressures of 1 GPa, the depth of the post-spinet transformation in the cold slabs is possibly controlled by nucleation kinetics. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0031-9201(01)00270-9

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The Fe-FeS melt is thought to be the major candidate of the outer core material. Its viscosity is one of the most important physical properties to study the dynamics of the convection in the outer core. We performed the in situ viscosity measurement of the Fe-FeS melt under high pressure using X-ray radiography falling sphere method with a novel sample assembly. Viscosity was measured in the temperature, pressure, and compositional conditions of 1233-1923 K, 1.5-6.9 GPa, and Fe-Fe72S28 (wt%), respectively. The viscosity coefficients obtained by 17 measurements change systematically in the range of 0.008-0.036 Pa s. An activation energy of the viscous flow, Q = 30.0 +/- 8.6 kJ/mol, and the activation volume, DeltaV = 1.5 +/- 0.7 x 10(-6) m(3)/mol, are determined as the temperature and pressure dependence, and the viscosity of the Fe72S28 melt is found to be smaller than that of the Fe melt by 15 +/- 10%. These tendencies can be well correlated with the structural variation of the Fe-FeS melt. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0012-821X(01)00374-0

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MINERALOGICAL SOC AMER  

Stokes' viscometry combined with in situ X-ray radiographic observation, using the 6-8 type multi-anvil press and synchrotron radiation, has been applied to the viscosity measurement of the Fe-FeS melt up to pressures of 7 GPa. The viscosity is found to be about 2 x 10(-2) Pa-s at 5 to 7 GPa and temperatures about 1350 K, in marked contrast to previous viscosity measurements, which showed high viscosity, 0.5 to 14 Pa-s, at 2 to 5 GPa (LeBlanc and Secco 1996). Our viscosity data, however, is consistent with all other evidence, which include 1 atm viscosity data, X-ray structure analysis, and ab initio simulations. Recent viscosity measurements (Dobson et al. 2000) also showed the viscosity of Fe-FeS melt to be about 10(-2) Pa-s at 2.5 GPa. Thus, we are confident that the viscosity of the Fe-FeS melt is close to a typical value (10(-2) Pa-s) of viscosity for liquid metal even at high pressures.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

In situ observations of the ilmenite-perovskite transition in MgSiO3 were carried out in a multianvil high-pressure apparatus interfaced with synchrotron radiation. The phase boundary between ilmenite and perovskite in the temperature range of 1300-1600 K was determined to be P (GPa) = 28.4(+/-0.4) - 0.0029(+/-0.0020)T (K) based on Jamieson's equation of state of gold [Jamieson et at., 1982] and P (GPa) = 27.3(+/-0.4) - 0.0035(+/-0.0024)T (K) based on Anderson's equation of state of gold [Anderson et al., 1989]. The consistency of our results, using Jamieson's equation of state, with previous studies obtained by quench methods leads us to conclude that the 660 km seismic discontinuity in the mantle can be attributed a phase transition to perovskite phase. However, the phase boundary based on the Anderson's equation of state implies that the depth of the 660-km seismic discontinuity does not match the pressure of this transition.

DOI： 10.1029/1999GL008446

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記述言語：日本語   出版者・発行元：日本鉱物科学会  

DOI： 10.2465/gkk.30.100

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER-VERLAG  

In situ synchrotron X-ray experiments in the system SnO2 were made at pressures of 4-29 GPa and temperatures of 300-1400 K using sintered diamond anvils in a 6-8 type high-pressure apparatus. Orthorhombic phase (alpha -PbO2 structure) underwent a transition to a cubic phase (Pa (3) over bar structure) at 18 GPa. This transition was observed at significantly lower pressures in DAC experiments. We obtained the isothermal bulk modulus of cubic phase K-0 = 252(28) GPa and its pressure derivative K' = 3.5(2.2). The thermal expansion coefficient of cubic phase at 25 GPa up to 1300 K was determined from interpolation of the P-V-T data obtained, and is 1.7(+/-0.7) x 10(-5) K-1 at 25 GPa.

DOI： 10.1007/s002690000108

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：AMER GEOPHYSICAL UNION  

An in situ X-ray observation of the postspinel transformation kinetics was made using intense synchrotron radiation. We confirmed that Mg2SiO4 spinel transforms into fine. lamellae of SiO2 stishovite and periclase, and/or MgSiO3 ilmenite and periclase as an intermediate step in the postspinel transformation. These metastable assemblages eventually disappear and form the stable assemblages of MgSiO3 perovskite and periclase. Initial grain size just after the postspinel; transformation drastically changes with overpressure. Viscosity of the subducting slab into the lower mantle, which is thought to be deformed by grain-size-sensitive creep, would depend on overpressure needed for the postspinel transformation at geological time scale.

DOI： 10.1029/1999GL008430

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：MINERALOGICAL SOC AMER  

Molten NaCl was analyzed by high-pressure X-ray diffraction experiments using synchrotron radiation up to 5 GPa and 1600 degrees C along the melting curve. The interference function Qi(Q), and the correlation function g(r) were derived from the diffraction data. The first-neighbor distance r(1) is about 2.7 Angstrom and the second-neighbor distance appears around 1.4r(1)-1.5r(1). The coordination number, CN, of the nearest neighbor ions increases with pressure from 3.5 at 0.1 MPa to 4.5 at 5 GPa. This is the evidence that the NaCl melt has a B1-like structure with large vacancies over this pressure range and becomes densified by an increase in CN as a result of second neighbor compaction.

DOI： 10.2138/am-1999-0317

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掲載種別：研究論文（学術雑誌）  

The phase boundary between spinel (γ phase) and MgSiO3 perovskite + MgO periclase in Mg2SiO4 was determined by in situ x-ray measurements by a combination of the synchrotron radiation source (SPring-8) and a large multianvil high-pressure apparatus. The boundary was determined at temperatures between 1400°to 1800°C, demonstrating that the postspinel phase boundary has a negative Clapeyron slope as estimated by quench experiments and thermodynamic analyses. The boundary was located at 21.1 (± 0.2) gigapascals, at 1600°C, which is ~2 gigapascals lower than earlier estimates based on other high-pressure studies.

DOI： 10.1126/science.279.5357.1698

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

X-ray diffraction experiments on the molten iron sulfide, FeS, were conducted up to 5 GPa by using synchrotron radiation. The correlation function g(r) for molten FeS was obtained just above the melting point. The near-neighbor structure of molten FeS does not change with pressure up to 5 GPa. The average nearest-neighbor distance is about 2.4 Å, which is correspond to the atomic distance between Fe and S. The average coordination number is about six. In FeS melt, Fe and S atoms surround each other with an octahedral coordination in near-neighbor region. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.

DOI： 10.4131/jshpreview.7.286

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AMER GEOPHYSICAL UNION  

The structures of molten KCl and KBr were studied by energy dispersive X ray diffraction experiments under high temperature and high pressure using synchrotron radiation. The radial distribution function g(r) for molten KCI and KBr was obtained at several points just above the melting temperatures up to 4 GPa. The second neighbor ionic distance decreases with pressure, although the nearest neighbor distance is almost constant. The coordination number of the nearest neighbor ions increases with pressure. Both melts transform from an open, simple-cubic-like structure into a more highly coordinated structure, probably a body-center-cubic-like structure. The structure of molten KCl changes before the crystalline phase but the molten KBr transforms into a dense phase about the same time as the solid. In both KCl and KBr melts the structural transition occurs over a narrow pressure range.

DOI： 10.1029/GM101p0241

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出版者・発行元：American Geophysical Union  

© 1998 by the American Geophysical Union. Anvils made of ADC (Advanced Diamond Composite) have been introduced for a double-stage multianvil system. Using a hybrid system for the second stage anvils, composed of four ADC and four WC cubes, we were able to produce pressures to 28 GPa and temperatures exceeding 1500°C. In situ X ray diffraction measurements on some minerals have been successfully performed with a combination of the present high pressure system and synchrotron radiation. Only in two runs some failures of ADC anvils have been observed out of more than 10 runs so far conducted using the MAX80 and MAX90 apparatus at the Photon Factory, National Laboratory for High Energy Physics (KEK). The present system may be used on a routine basis for experiments under pressures to 30 GPa, and at temperatures approaching 2000°C within the force capacity of these apparatus.

DOI： 10.1029/gm101p0001

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

We present the first measurements of carbonate melt viscosity and density at mantle pressures and temperatures and provide important data for modelling carbonatite behaviour within the mantle. Synchrotron radiation was used to observe falling spheres with high atomic number in situ, allowing precise determination of high terminal velocities over short fall distances, The measured viscosities of 1.5 (5) x 10(-2) to 5 (2.5) x 10(-3) Pas are the lowest of any known terrestrial magma types and these measurements extend the region of measurable viscosity at high pressure by at least 2 orders of magnitude. Accurate measurements of K2Ca(CO3)(2) melt density were performed at atmospheric pressure:
rho(g/cm(3)) = 2.39(2) - 3.85(15) x 10(-4)T(degrees C)
and are in complete agreement with the predictions of Wolff (1995). The high-pressure density measurements also agree well with molecular dynamics predictions of carbonate melt compressibility.

DOI： 10.1016/0012-821X(96)00139-2

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：GORDON BREACH SCI PUBL LTD  

Energy-dispersive X-ray diffraction experiments of molten KCI under high pressure have been carried out by using synchrotron radiation. The diffraction profiles of molten KCl were acquired just above the melting temperature of KCl up to 4 GPa. The reduced structure factor S(Q)'s for molten KCI do not show any change in their primary features, except for a gradual increase in the first peak intensity with increasing pressure. This implies that molten KCl does not show a first-order phase transition, such as the B1-B2 transition, found in solid KCl, but that the local structure in molten KCl must be changed by compression. According to a molecular-dynamics simulation, this change of S(Q) can be explained by a continuous increase in the coordination number of the nearest-neighbor ions in molten KCl with pressure.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SPRINGER VERLAG  

In situ X-ray diffraction study on KAlSi3O8 has been performed using the cubic type high pressure apparatus, MAX90, combined with synchrotron radiation. We determined the phase relations of sanidine, the wadeite-type K2Si4O9 + kyanite (Al2SiO5) + coesite (SiO2) assemblage, and hollandite-type KAlSi3O8, including melting temperatures of potassic phases, up to 11 GPa. Our data on subsolidus phase boundaries are close to the recent data of Yagi and Akaogi (1991). Melting relations of sanidine are consistent with the low pressure data of Lindsley (1966). The breakdown of sanidine into three phases reduces melting temperature, and wadeite-type K2Si4O9 melts first around 1500 degrees C in three phase coexisting region. Melting point of hollandite-type KAlSi3O8 is between 1700 degrees C and 1800 degrees C at 11 GPa. If these potassic phases host potassium in the earth's mantle, the true mantle solidus temperature will be much lower than the reported dry solidus temperature of peridotite.

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1126/science.265.5176.1202

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：AIP PRESS  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1029/GL017i013p02457

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出版者・発行元：American Geophysical Union  

DOI： 10.1029/gm039p0095

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：The Japan Society of High Pressure Science and Technology  

In order to understand the formation, evolution and dynamic processes of the molten core of the terrestrial planets, knowledge of the physical properties, such as viscosity and density, of the molten iron alloy is required. Recent progress in the high-pressure technology combined with synchrotron radiation allows us to measure such properties at high-temperature and high-pressure. In this article, recent advances in the high-pressure research of molten iron alloys are reviewed.

DOI： 10.4131/jshpreview.12.138

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00198963460?from=CiNii

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記述言語：日本語   出版者・発行元：The Crystallographic Society of Japan  

Performances of the high pressure in-situ X-ray observation system using a large volume multi anvil press installed at the High-Pressure Mineral Physics Experimental Station at BL04B1 in SPring-8 are introduced. Recent results obtained with this system are reviewed.

DOI： 10.5940/jcrsj.42.24

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00066980582?from=CiNii

記述言語：日本語   出版者・発行元：日本放射光学会  

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記述言語：英語  

DOI： 10.4131/jshpreview.9.71

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The SPring-8 will open for public use in October, 1997. Three beamlines are now under construction for high pressure research with large volume high pressure apparatus. Two multi-anvil apparatus will be installed on these beamlines. One is a 1500 ton press with a big DIA type guide-block for two stage compression, which is used for the energy dispersive x-ray diffraction study. The other is a 180 ton small DIA press similar to MAX90 at the Photon Factory, which is used for both energy and angle dispersive diffraction as well as an x-ray absorption study. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.

DOI： 10.4131/jshpreview.7.1484

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記述言語：日本語   出版者・発行元：一般社団法人日本物理学会  

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記述言語：日本語   出版者・発行元：岩波書店  

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