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Abeykoon, S.*; Howard, C.*; Dominijanni, S.*; Eberhard, L.*; Kurnosov, A.*; Frost, D. J.*; Boffa Ballaran, T.*; Terasaki, Hidenori*; Sakamaki, Tatsuya*; Suzuki, Akio*; et al.
Journal of Geophysical Research; Solid Earth, 128(9), p.e2023JB026710_1 - e2023JB026710_17, 2023/09
Times Cited Count：0 Percentile：0.01(Geochemistry & Geophysics)Small amounts of iron sulphide minerals are found in most rocks from the Earth's mantle and as inclusions trapped in natural diamonds. Hydrogen may dissolve into iron sulphide minerals under high pressures and temperature, but is most likely lost once pressure and temperature are removed. In this study, we determined deuterium contents in iron sulphide, held under high pressure and temperature conditions, using neutron diffraction measurements with 6-ram multi-anvil press at PLANET, J-PARC. Deuterium contents in iron sulphide were measured at high-P, up to 11.4 GPa and high-T to 1300 K in in situ neutron diffraction experiments. The total deuterium content increases with both P and T. The results are used to estimate hydrogen contents of iron sulphide minerals in the deep continental lithospheric mantle, which are found to be in the range 1700-2700 ppm. This corresponds to approximately 2-3 ppm of hydrogen in the bulk mantle.
Ikuta, Daijo*; Otani, Eiji*; Sano, Asami; Shibazaki, Yuki*; Terasaki, Hidenori*; Yuan, L.*; Hattori, Takanori
Scientific Reports (Internet), 9, p.7108_1 - 7108_8, 2019/05
Times Cited Count：38 Percentile：92.44(Multidisciplinary Sciences)Hydrogen is likely one of the light elements in the Earth's core. Despite its importance, no direct observation has been made of hydrogen in an iron lattice at high pressure. We made the first direct determination of site occupancy and volume of interstitial hydrogen in a face-centered cubic (fcc) iron lattice up to 12 GPa and 1200 K using the in situ neutron diffraction method. At pressures 
5 GPa, the hydrogen content in the fcc iron hydride lattice (x) was small at x 0.3, but increased to x 
0.8 with increasing pressure. Hydrogen atoms occupy both octahedral (O) and tetrahedral (T) sites; typically 0.870 in O-sites and 0.057 in T-sites at 12 GPa and 1200 K. The fcc lattice expanded approximately linearly at a rate of 2.22 
per hydrogen atom, which is higher than previously estimated (1.9 /H). The lattice expansion by hydrogen dissolution was negligibly dependent on pressure. The large lattice expansion by interstitial hydrogen reduced the estimated hydrogen content in the Earth's core that accounted for the density deficit of the core. The revised analyses indicate that whole core may contain hydrogen of 80 times of the ocean mass with 79 and 0.8 ocean mass for the outer and inner cores, respectively.
-bearing Mg-perovskite and its crystal chemistry at high pressureMashimo, Izumi*; Otani, Eiji*; Hirao, Naohisa*; Mitsui, Takaya; Masuda, Ryo*; Seto, Makoto*; Sakai, Takeshi*; Takahashi, Suguru*; Nakano, Satoshi*
American Mineralogist, 99(8-9), p.1555 - 1561, 2014/08
Times Cited Count：7 Percentile：24.02(Geochemistry & Geophysics)Sakamaki, Tatsuya*; Suzuki, Akio*; Otani, Eiji*; Terasaki, Hidenori*; Urakawa, Satoru*; Katayama, Yoshinori; Funakoshi, Kenichi*; Wang, Y.*; Hernlund, J. W.*; Ballmer, M. D.*
Nature Geoscience, 6(12), p.1041 - 1044, 2013/12
Times Cited Count：128 Percentile：96.48(Geosciences, Multidisciplinary)The bounday between Earth's rigid lighosphere and the underlying, ductile ashenosphere is marked by a distinct siseismic discontinuity. We measure the density, viscosity and structure of basaltic magmas using high-pressure and high-temperature experiments and in situ X-ray analysis under pressure of up to 5.5 GPa. We find that the magmas rapidly become denser with increasing presure and show a viscosity minimum near 4 GPa. Magma mobility determined by the density and viscosity data exhibits a peak at pressures corresponding to depths of 120-150 km, within the asthenosphere. The diminishing mobility of magma in Earth's asthenosphere as the mlets ascend could lead to excessive melt accumulation at depths of 80-100 km, at the lithosphere-asthenosphere boundary. It is concluded that the observed seismic discontinuity at the lithosphere-asthenosphere boundary records this accumulation of melt.
Sano, Asami; Kuribayashi, Takahiro*; Komatsu, Kazuki*; Yagi, Takehiko*; Otani, Eiji*
Physics of the Earth and Planetary Interiors, 189(1-2), p.56 - 62, 2011/11
Times Cited Count：22 Percentile：52.77(Geochemistry & Geophysics)A neutron powder diffraction experiment was conducted to refine the hydrogen position of Mg-endmember deuterated wadsleyite. Preliminary refinement using the dry-structure determined by single crystal X-ray diffraction reveals a maximum peak Q1 of nuclear density in the difference Fourier map at the M3 octahedral edge, between the O1 and O4 atoms. Full Rietveld refinement was conducted assuming that the maximum peak corresponds to deuterium atom. The deuterium position was determined as (0.096, 0.289, 0.315) with occupancy of 8.2%. The structure determined by this study predicts that the hydration of wadsleyite has an anisotropic effect on diffusion properties.
Nishida, Keisuke*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Sakamaki, Tatsuya*; Terasaki, Hidenori*; Katayama, Yoshinori
American Mineralogist, 96(5-6), p.864 - 868, 2011/05
Times Cited Count：32 Percentile：69.49(Geochemistry & Geophysics)The density of liquid iron sulfide (FeS) was measured up to 3.8 GPa and 1800 K using the X-ray absorption method. The compression curve of the liquid FeS can be fitted using the Vinet equation of state. Isothermal bulk modulus and its temperature and pressure derivatives were determined by a non-linear least squares fit. Liquid FeS is more compressible than Fe-rich Fe-S liquid.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Terasaki, Hidenori*; Katayama, Yoshinori
American Mineralogist, 96(4), p.553 - 557, 2011/04
Times Cited Count：31 Percentile：68.33(Geochemistry & Geophysics)The density of carbonated peridotite magma was measured up to 3.8 GPa and 2100 K using an X-ray absorption method. 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. Our results show that the partial molar volume of CO is less compressible than that of HO, suggesting that, on an equal molar basis, CO is more effective than HO in reducing peridotite melt density at high pressure.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Katayama, Yoshinori; Zhao, D.*
Earth and Planetary Science Letters, 299(3-4), p.285 - 289, 2010/11
Times Cited Count：29 Percentile：58.17(Geochemistry & Geophysics)The density of the Apollo 14 black glass melt, which has the highest TiO 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, its pressure derivative, and the temperature derivative of the bulk modulus. Implication for heterogeneities in the lunar mantle is discussed.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Katayama, Yoshinori
American Mineralogist, 95(1), p.144 - 147, 2010/01
Times Cited Count：37 Percentile：70.43(Geochemistry & Geophysics)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-Murnaghan equation of state yielded the isothermal bulk modulus, 
GPa, its pressure derivative, 
, and the derivative of bulk modulus 
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.
Sakamaki, Tatsuya*; Otani, Eiji*; Urakawa, Satoru*; Suzuki, Akio*; Katayama, Yoshinori
Earth and Planetary Science Letters, 287(3-4), p.293 - 297, 2009/10
Times Cited Count：57 Percentile：78.64(Geochemistry & Geophysics)The density of hydrous peridotite magma containing 5wt.% HO 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-Murnagan equation of state yields isothermal bulk modulus 
GPa, its pressure derivative 
and the temperature derivative of the bulk modulus 
GPa/K at 1773K. 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.
Otani, Eiji*; Suzuki, Akio*; Ando, Ryota*; Urakawa, Satoru*; Funakoshi, Kenichi*; Katayama, Yoshinori
Advances in High-Pressure Technology for Geophysical Applications, p.195 - 209, 2005/09
This paper summarizes the techniques for the viscosity and density measurements of silicate melt 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 the pressures above 6 GPa at high temperature. We summarize the details of the experimental technique of the viscosity measurement, and the results of the measurements of some silicate melts such as the albite and diopside-jadeite systems. X-ray absorption method is applied to measure the density of the silicate glasses such as the basaltic glass and iron sodium disilicate glass up to 5 GPa at high temperature. A diamond capsule, which is not reactive with the glass, 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.
SiO
Kubo, Tomoaki*; Otani, Eiji*; Kato, Takumi*; Urakawa, Satoru*; Suzuki, Akio*; Kambe, Yuichi*; Funakoshi, Kenichi*; Utsumi, Wataru; Kikegawa, Takumi*; Fujino, Kiyoshi*
Physics of the Earth and Planetary Interiors, 129(1-2), p.153 - 171, 2002/01
Times Cited Count：50 Percentile：66.4(Geochemistry & Geophysics)no abstracts in English
SiOKubo, Tomoaki*; Otani, Eiji*; Kato, Takumi*; Urakawa, Satoru*; Suzuki, Akio*; Kambe, Yuichi*; Funakoshi, Kenichi*; Utsumi, Wataru; Fujino, Kiyoshi*
Geophysical Research Letters, 27(6), p.807 - 810, 2000/03
Times Cited Count：33 Percentile：62.01(Geosciences, Multidisciplinary)no abstracts in English
Sano, Asami; Yagi, Takehiko*; Komatsu, Kazuki*; Otani, Eiji*
no journal, ,
Neutron diffraction experiments have been succeeded in determining of hydrogen position in many hydrous minerals. By contrast, little application to nominally anhydrous minerals has been done, despite its importance in the mantle. Wadsleyite, a high pressure polymorph of olivine, is a main constituent of shallower part of the mantle transition zone at the depth from 410 to 520 km. Ever since Smyth (1987) predicted that protonation of O1 site of wadsleyite results in significant amount of water content up to 3.3 wt%, hydration of wadsleyite and related change in physical properties has attracted much attention. However, several mechanisms of protonation have been proposed and the position of hydrogen in wadsleyite still remains controversial, because previous studies are based on X-ray diffraction and spectroscopic methods. To determin the hydrogen position precisely, we conducted neutron diffraction experiment on hydrated and deuterated wadsleyite at D20 in ILL, in France.
Sano, Asami; Kuribayashi, Takahiro*; Komatsu, Kazuki*; Yagi, Takehiko*; Otani, Eiji*
no journal, ,
Wadsleyite is a main constituent of upper part of the mantle transition zone, at 410 - 520 km depth of the earth. Since the Smyth's prediction, wadsleyite, which is one of the nominally anhydrous mineral (NAMs) have been attracted as a host of water in the mantle. Subsequent studies have also revealed that a small amount of hydrogen cause changes of some physical properties of wadsleyite dramatically. To understand the effect of hydration of wadsleyite on its physical properties, it is essential to know the position of hydrogen in the structure. In this study, we intend to determine the hydrogen position of wadsleyite by neutron powder diffraction experiment. Full Rietveld refinement with deuterium was successfully conducted, which revealed that an O-D bond is formed at the edge of the M3 octahedron between the O1...O4 (3.074 A).
Sano, Asami; Komatsu, Kazuki*; Kuribayashi, Takahiro*; Yagi, Takehiko*; Otani, Eiji*
no journal, ,
New neutron diffraction beamline for high pressure experiment is under construction at MLF, J-PARC and will be available soon. In this paper, I will present examples of neutron diffraction studies on hydrous and nominally anhydrous minerals to show a potential utility of neutron diffraction in the investigation of high pressure mineral physics. (1) Emboss hydrogen in mineral; Neutron scattering length of hydrogen (deuterium) is sufficient compared to the main constituent of minerals, thus neutron diffraction is a powerful tool to investigate the hydrogen in minerals. I will present the result of neutron diffraction study on nominally anhydrous mineral of wadsleyite. (2) Distinguish Isotopes; Another characteristic property of neutron scattering is an ability to distinguish isotopes. Neutron diffraction on 
-AlOOH and -AlOOD shows the strong isotope effects on the geometry of hydrogen bond.
