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Journal Articles

Behavior of light elements in iron-silicate-water-sulfur system during early Earth's evolution

Iizuka, Riko*; Goto, Hirotada*; Shito, Chikara*; Fukuyama, Ko*; Mori, Yuichiro*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Kagi, Hiroyuki*

Scientific Reports (Internet), 11(1), p.12632_1 - 12632_10, 2021/06

 Times Cited Count:0 Percentile:0.01(Multidisciplinary Sciences)

The Earth's core consist of Fe-Ni alloy with some light elements (H, C, O, Si, S etc.). Hydrogen (H) is the most abundant element in the universe and one of the promising candidates. In this study, we have investigated the effects of sulfur(S) on hydrogenation of iron-hydrous silicate system containing saturated water in the ideal composition of the primitive Earth. We observed a series of phase transitions of Fe, dehydration of the hydrous mineral, and formation of olivine and enstatite with increasing temperature. The FeS formed as the coexisting phase of Fe under high-pressure and temperature condition, but its unit cell volume did not increase, suggesting that FeS is hardly hydrogenated. Recovered samples exhibited that H and S can be incorporated into solid Fe, which lowers the melting temperature as Fe(H$$_{x}$$)-FeS system. No detection of other light elements (C, O, Si) in solid Fe suggests that they dissolve into molten iron hydride and/or FeS in the later process of Earth's core-mantle differentiation.

Journal Articles

${{it In situ}}$ neutron diffraction of iron hydride in iron-silicate-water system under high pressure and high temperature condition

Iizuka, Riko*; Yagi, Takehiko*; Goto, Hirotada*; Okuchi, Takuo*; Hattori, Takanori; Sano, Asami

Hamon, 27(3), p.104 - 108, 2017/08

Hydrogen is the most abundant element in the solar system and is considered to be one of the promising candidates of the light elements in the Earth's core. However, the amount of hydrogen dissolved in the core and its process are still unknown because hydrogen cannot be detected by X ray and easily escapes from iron at ambient conditions. In this study, we have conducted high-pressure and high-temperature in-situ neutron diffraction experiments on the iron-hydrous mineral system using PLANET in J-PARC. We observed that the water, which was dissociated from a hydrous mineral, reacted with iron to form both iron oxide and iron hydride at about 4 GPa. Iron hydride remained stable after further increase in temperature. This formation occurred at 1000K, where no materials melted. This suggests that hydrogen dissolved into iron before any other light elements dissolved in the very early stage of the Earth's evolution.

Journal Articles

Hydrogenation of iron in the early stage of Earth's evolution

Iizuka, Riko*; Yagi, Takehiko*; Goto, Hirotada*; Okuchi, Takuo*; Hattori, Takanori; Sano, Asami

Nature Communications (Internet), 8, p.14096_1 - 14096_7, 2017/01

AA2016-0524.pdf:0.73MB

 Times Cited Count:26 Percentile:88.17(Multidisciplinary Sciences)

Density of the Earth's core is lower than that of pure iron and the light element(s) in the core is a long-standing problem. Hydrogen is the most abundant element in the solar system and thus one of the important candidates. However, the dissolution process of hydrogen into iron remained unclear. Here we carry out high-pressure and high-temperature in situ neutron diffraction experiments and clarify that when the mixture of iron and hydrous minerals are heated, iron is hydrogenized soon after the hydrous mineral is dehydrated. This implies that early in the Earth's evolution, as the accumulated primordial material became hotter, the dissolution of hydrogen into iron occurred before any other materials melted. This suggests that hydrogen is likely the first light element dissolved into iron during the Earth's evolution and it may affect the behaviour of the other light elements in the later processes.

Journal Articles

Phase transitions and hydrogen bonding in deuterated calcium hydroxide; High-pressure and high-temperature neutron diffraction measurements

Iizuka, Riko*; Komatsu, Kazuki*; Kagi, Hiroyuki*; Nagai, Takaya*; Sano, Asami; Hattori, Takanori; Goto, Hirotada*; Yagi, Takehiko*

Journal of Solid State Chemistry, 218, p.95 - 102, 2014/10

 Times Cited Count:6 Percentile:34.03(Chemistry, Inorganic & Nuclear)

In situ neutron diffraction measurements combined with the pulsed neutron source at the Japan Proton Accelerator Research Complex (J-PARC) were conducted on high-pressure polymorphs of deuterated portlandite (Ca(OD)$$_{2}$$) using a Paris-Edinburgh cell and a multi-anvil press. The atomic positions including hydrogen for the unquenchable high-pressure phase at room temperature (phase II') were first clarified. The bent hydrogen bonds under high pressure were consistent with results from Raman spectroscopy. The structure of the high-pressure and high-temperature phase (Phase II) was concordant with that observed previously by another group for a recovered sample. The observations elucidate the phase transition mechanism among the polymorphs, which involves the sliding of CaO polyhedral layers, position modulations of Ca atoms, and recombination of Ca-O bonds accompanied by the reorientation of hydrogen to form more stable hydrogen bonds.

Journal Articles

Compression behaviors of distorted rutile-type hydrous phases, MOOH (M = Ga, In, Cr) and CrOOD

Sano, Asami; Yagi, Takehiko*; Okada, Taku*; Goto, Hirotada*; Kikegawa, Takumi*

Physics and Chemistry of Minerals, 39(5), p.375 - 383, 2012/05

 Times Cited Count:17 Percentile:57.49(Materials Science, Multidisciplinary)

X-ray diffraction measurements of distorted rutile-type oxyhydroxides $$beta$$-GaOOH, InOOH, $$beta$$-CrOOH, and $$beta$$-CrOOD were taken at a maximum pressure of up to 35 GPa under quasi-hydrostatic conditions, at ambient temperature. Anomalies in the evolution of the relative lattice constants and the axial ratios of $$beta$$-GaOOH, InOOH, and $$beta$$-CrOOD suggest anisotropic stiffening along the a- and/or b-axes where the hydrogen bond is formed. The changes were observed at 15 GPa in $$beta$$-GaOOH and InOOH and at 4 GPa in $$beta$$-CrOOD. The pressures were higher in oxyhydroxides that have longer O...O distances of the hydrogen bond at ambient pressure. In contrast, such stiffening behavior was not observed in CrOOH, which has a significant short O...O distance and strong hydrogen bond. The stiffening behaviors observed in the present study can be attributed to the symmetrization of the hydrogen bonds in oxyhydroxides, as was previously found in $$delta$$-AlOOH(D).

Journal Articles

The Crystal structure of $$delta$$-Al(OH)$$_{3}$$; Neutron diffraction measurements and ab initio calculations

Matsui, Masanori*; Komatsu, Kazuki*; Ikeda, Emi*; Sano, Asami; Goto, Hirotada*; Yagi, Takehiko*

American Mineralogist, 96(5-6), p.854 - 859, 2011/05

 Times Cited Count:12 Percentile:40.6(Geochemistry & Geophysics)

Neutron powder diffraction analyses of $$delta$$-Al(OD)$$_{3}$$ revealed that the crystals are orthorhombic with space group ${it P}$2$$_{1}$$2$$_{1}$$2$$_{1}$$, but not ${it Pnma}$ as reported previously by X-ray diffraction data. The initial lattice parameters and the atomic positions of both Al and O were taken from previous X-ray structural analyses for the ${it Pnma}$ structure, while the H atom positions were determined using ab initio calculations. The $$delta$$-Al(OH)$$_{3}$$ structure possesses one relatively long and two short O-H...O hydrogen bonds. Ab initio calculations are also used to find that $$delta$$-Al(OH)$$_{3}$$ with space group ${it P}$2$$_{1}$$2$$_{1}$$2$$_{1}$$ transforms to another high pressure polymorph with space group ${it Pnma}$ at around 67 GPa, and that the two short hydrogen bonds in $$delta$$-Al(OH)$$_{3}$$ become both symmetric through the transformation, in which the protons are located at the midpoints of the O...O hydrogen bonds.

Oral presentation

Change in compression in M$$^{3+}$$OOH oxyhydroxide and implication for hydrogen bond symmetrization

Sano, Asami; Yagi, Takehiko*; Okada, Taku*; Goto, Hirotada*; Kagi, Hiroyuki*; Nagai, Takaya*; Kikegawa, Takumi*

no journal, , 

Oral presentation

6-rams press for neutron diffraction experiment

Sano, Asami; Hattori, Takanori; Arima, Hiroshi*; Yamada, Akihiro*; Goto, Hirotada*; Okada, Taku*; Yagi, Takehiko*

no journal, , 

Hydrogen is considered to play an important role in the deep mantle since it has a significant effect on the physical properties of minerals and rocks. Beamline "PLANET" at BL11, MLF in J-PARC is aimed at investigating hydrogen in minerals and rocks in the earth's interior. To generate high pressure and high temperature conditions, 6-rams multi-anvil press is installed in BL11. The press consists from six hydraulic rams mounted on a flame with maximum load of 500-ton in each ram. Each ram is controlled independently by six plunger pumps so as to retain the deviation of the anvil stroke within 10 micron. During the experiment, divergence of bottom anvil stroke and other 5 anvils stroke are in the range of 1 micron, suggesting that each ram is controlled successfully by independent plunger pump. Generated pressure was determined by resistance measurement experiment of Bi. Bi III-V transition at 7.7 GPa was detected at 1390 kN /1 ram for TEL10, 644 kN /1 ram for TEL 7 6-6 anvil.

Oral presentation

6-rams press for high pressure and high temperature neutron diffraction experiment

Sano, Asami; Hattori, Takanori; Arima, Hiroshi*; Yamada, Akihiro*; Goto, Hirotada*; Okada, Taku*; Yagi, Takehiko*; Utsumi, Wataru

no journal, , 

Beamline "PLANET" at BL11, MLF in J-PARC is aimed at investigating hydrogen in minerals and rocks in the earth's interior. To generate high pressure and high temperature conditions, 6-rams multi-anvil press "ATSUHIME" is installed in BL11. 6-rams press is suitable for neutron diffraction experiment because it has a wide window surrounding the sample compared to other multi anvil press using guide block. It allows us to place the insertion device and radial collimator close to the sample, and to cover wide diffraction angle and azimuth angle. The detail of design and performance of the 6-rams press will be presented.

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