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Journal Articles

Crystal and magnetic structures of double hexagonal close-packed iron deuteride

Saito, Hiroyuki*; Machida, Akihiko*; Iizuka, Riko*; Hattori, Takanori; Sano, Asami; Funakoshi, Kenichi*; Sato, Toyoto*; Orimo, Shinichi*; Aoki, Katsutoshi*

Scientific Reports (Internet), 10, p.9934_1 - 9934_8, 2020/06

 Times Cited Count:0 Percentile:100(Multidisciplinary Sciences)

Neutron powder diffraction profiles were collected for iron deuteride (FeDx) while the temperature decreased from 1023 to 300 K for a pressure range of 4-6 GPa. The $$varepsilon$$' deuteride with a double hexagonal close-packed (dhcp) structure, which coexisted with other stable or metastable deutrides at each temperature and pressure condition, formed solid solutions with a composition of FeD$$_{0.68(1)}$$ at 673 K and 6.1 GPa and FeD$$_{0.74(1)}$$ at 603 K and 4.8 GPa. Upon stepwise cooling to 300 K, the D-content x increased to a stoichiometric value of 1.0 to form monodeuteride FeD$$_{1.0}$$. In the dhcp FeD$$_{1.0}$$ at 300 K and 4.2 GPa, dissolved D atoms fully occupied the octahedral interstitial sites, slightly displaced from the octahedral centers in the dhcp metal lattice, and the dhcp sequence of close-packed Fe planes contained hcp-stacking faults at 12%. Magnetic moments with 2.11 $$pm$$ 0.06 B/Fe-atom aligned ferromagnetically in parallel on the Fe planes.

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:20 Percentile:11.8(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

Foods being better or worse after $$gamma$$-irradiation

Chiba, Etsuko*; Iizuka, Tomoko*; Ichikawa, Mariko*; Ukai, Mitsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

Hoshasen To Sangyo, (137), p.29 - 32, 2014/12

no abstracts in English

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:3 Percentile:80.5(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

Site occupancy of interstitial deuterium atoms in face-centred cubic iron

Machida, Akihiko; Saito, Hiroyuki; Sugimoto, Hidehiko*; Hattori, Takanori; Sano, Asami; Endo, Naruki*; Katayama, Yoshinori; Iizuka, Riko*; Sato, Toyoto*; Matsuo, Motoaki*; et al.

Nature Communications (Internet), 5, p.5063_1 - 5063_6, 2014/09

 Times Cited Count:28 Percentile:17.88(Multidisciplinary Sciences)

Iron hydride FeH$$_x$$, is thermodynamically stable only at high hydrogen pressure of several GPa. To investigate the hydrogenation process and hydrogen state in iron hydride, it is necessary to carry out the in-situ measurement under high pressure and high temperature. In this study, we performed the in-situ neutron diffraction measurement of Fe-D system using the high pressure neutron diffractometer PLANET in the MLF, J-PARC, and determined the deuterium occupying sites and occupancies in fcc-FeD$$_x$$. We found the minor occupation of tetrahedral sites under high pressure and high temperature. We considered the mechanism of the minor occupation based on the Quantum-mechanical calculation.

Journal Articles

Pressure responses of portlandite and H-D isotope effects on pressure-induced phase transitions

Iizuka, Riko*; Kagi, Hiroyuki*; Komatsu, Kazuki*; Ushijima, Daichi*; Nakano, Satoshi*; Sano, Asami; Nagai, Takaya*; Yagi, Takehiko*

Physics and Chemistry of Minerals, 38(10), p.777 - 785, 2011/12

 Times Cited Count:6 Percentile:73.68(Materials Science, Multidisciplinary)

The pressure responses of portlandite and the isotope effect on the phase transition were investigated at room temperature from single-crystal Raman and IR spectra and from powder X-ray diffraction using diamond anvil cells under quasi-hydrostatic conditions in a helium pressure-transmitting medium. Phase transformation and subsequent peak broadening observed from the Raman and IR spectra of Ca(OH)$$_{2}$$ occurred at lower pressures than those of Ca(OD)$$_{2}$$. In contrast, no isotope effect was found on the volume and axial compressions observed from powder X-ray diffraction patterns. X-ray diffraction lines attributable to the high-pressure phase remained up to 28.5 GPa, suggesting no total amorphization in a helium pressure medium within the examined pressure region. These results suggest that the H-D isotope effect is engendered in the local environment surrounding H(D) atoms.

Journal Articles

Sprouting and rooting inhibition of garlic with Co-60 $$gamma$$-rays

Kobayashi, Yasuhiko; Kikuchi, Masahiro; Todoriki, Setsuko*; Saito, Kimie*; Katsura, Yoko*; Kameya, Hiromi*; Ichikawa, Mariko*; Iizuka, Tomoko*; Chiba, Etsuko*; Ukai, Mitsuko*

Shokuhin Shosha, 45(1-2), p.26 - 33, 2010/09

Effect of $$gamma$$-irradiation on sprouting and rooting of garlic was investigated. Sprouting and rooting of garlic were inhibited by irradiation of bulbs at 2 months after harvest with doses more than 30 Gy. Four weeks-later irradiation requires higher doses to complete sprouting/rooting inhibition.

Oral presentation

Risk communication for the acceptance of irradiated food

Ichikawa, Mariko*; Iizuka, Tomoko*; Gamo, Emi*; Kobori, Emiko*; Shibuya, Michiko*; Shibosawa, Hisako*; Chiba, Etsuko*; Yokoyama, Tsutomu*; Fukutomi, Fumitake*; Todoriki, Setsuko*; et al.

no journal, , 

no abstracts in English

Oral presentation

Study of effectiveness of irradiation in shelf-life extension of fresh vegetables

Iizuka, Tomoko*; Ichikawa, Mariko*; Kobori, Emiko*; Shibuya, Michiko*; Shibosawa, Hisako*; Todoriki, Setsuko*; Ukai, Mitsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Growth of ferroelectric ice XI doped with alkali metal hydroxide observed using neutron diffraction

Arakawa, Masashi*; Komatsu, Kazuki*; Iizuka, Riko*; Kagi, Hiroyuki; Fernandez-Baca, J. A.*; Chakoumakos, B.*; Yamauchi, Hiroki; Fukazawa, Hiroshi

no journal, , 

We prepared ice XI from different kinds of alkali metal hydroxide solutions with different concentrations, and measured neutron powder diffraction at JRR-3 (Japan Atomic Energy Agency, Japan) and HFIR (Oak Ridge National Laboratory, TN, USA). Rietveld analysis was carried out for the obtained diffraction patterns using a two-phase model, which includes ices Ih and XI. The hydrogen-ordered structure in the lithium-doped ice was the same as that in the sodium-doped and potassium-doped ices. We also confirmed the optimum formation condition of ice XI for the temperature history and concentration of solution. Furthermore, our results indicate that the phase transition from ice Ih to XI occurs in the doped ice that had once been ice XI to a notably larger degree than in the doped ice that had never transformed to ice XI. We named this phenomenon memory effect of hydrogen ordering.

Oral presentation

High-pressure neutron diffraction experiments at TAKUMI in J-PARC

Abe, Jun; Hattori, Takanori; Arima, Hiroshi; Sano, Asami; Fukazawa, Hiroshi; Utsumi, Wataru; Komatsu, Kazuki*; Arakawa, Masashi*; Iizuka, Riko*; Kagi, Hiroyuki*; et al.

no journal, , 

In order to confirm the feasibility of high-pressure neutron diffraction at TAKUMI, we have performed a number of R&Ds using a various high-pressure devices. Optimization of materials such as anvil and pressure medium and developments of collimators have made possible reduction of background and contamination noise. Incident and diffracted neutron beams travel through high-pressure device, which causes attenuation of neutron. We investigated the method of attenuation correction.

Oral presentation

Sprout inhibition of garlic with Co-60 $$gamma$$-rays

Kobayashi, Yasuhiko; Kikuchi, Masahiro; Todoriki, Setsuko*; Saito, Kimie*; Katsura, Yoko*; Kameya, Hiromi*; Ichikawa, Mariko*; Iizuka, Tomoko*; Chiba, Etsuko*; Ukai, Mitsuko*

no journal, , 

no abstracts in English

Oral presentation

Taste comparison of spices; Radiation sterilization and heating sterilization

Ichikawa, Mariko*; Iizuka, Tomoko*; Chiba, Etsuko*; Okamura, Hiroyuki*; Tabei, Yutaka*; Morita, Maki*; Yokoyama, Tsutomu*; Fukutomi, Fumitake*; Sakagami, Chiharu*; Ukai, Mitsuko*; et al.

no journal, , 

no abstracts in English

Oral presentation

Study on quality of irradiated foods for fruitful risk communication

Chiba, Etsuko*; Iizuka, Tomoko*; Ichikawa, Mariko*; Yokoyama, Tsutomu*; Sakagami, Chiharu*; Ukai, Mitsuko*; Todoriki, Setsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Powder neutron diffraction study using high-pressure cells at J-PARC/TAKUMI

Abe, Jun; Arima, Hiroshi; Hattori, Takanori; Sano, Asami; Fukazawa, Hiroshi; Utsumi, Wataru; Komatsu, Kazuki*; Arakawa, Masashi*; Iizuka, Riko*; Kagi, Hiroyuki; et al.

no journal, , 

We have performed high-pressure neutron diffraction experiments at TAKUMI in J-PARC. Three types of high-pressure devices are used, Paris-Edinburgh Press, Palm cubic anvil cell and NPD-DAC. Optimization of materials such as anvil and pressure medium and developments of collimators have made possible reduction of background and contamination noise. Incident and diffracted neutron beams travel through high-pressure device, which causes attenuation of neutron. We have studied the method of attenuation correction and analyzed crystal structure using corrected neutron diffraction pattern.

Oral presentation

Foods being better or worse after irradiation

Chiba, Etsuko*; Iizuka, Tomoko*; Ichikawa, Mariko*; Ukai, Mitsuko*; Todoriki, Setsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Study on quality of irradiated dried fruit

Iizuka, Tomoko*; Ichikawa, Mariko*; Chiba, Etsuko*; Ukai, Mitsuko*; Todoriki, Setsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

Study on quality of irradiated fresh fruit

Chiba, Etsuko*; Iizuka, Tomoko*; Ichikawa, Mariko*; Ukai, Mitsuko*; Todoriki, Setsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

Oral presentation

A Study on effects and influence of $$gamma$$-irradiation to foodstuffs of the Japanese-style dishes

Chiba, Etsuko*; Iizuka, Tomoko*; Ichikawa, Mariko*; Ukai, Mitsuko*; Kikuchi, Masahiro; Kobayashi, Yasuhiko

no journal, , 

no abstracts in English

37 (Records 1-20 displayed on this page)