Atomic distribution and local structure in ice VII from in situ neutron diffraction

Yamashita, Keishiro*; Komatsu, Kazuki*; Klotz, S.*; Fabelo, O.*; Fernndez-Daz, M. T.*; Abe, Jun*; Machida, Shinichi*; Hattori, Takanori; Irifune, Tetsuo*; Shimmei, Toru*; et al.

Proceedings of the National Academy of Sciences of the United States of America, 119(40), p.e2208717119_1 - e2208717119_6, 2022/10

https://doi.org/10.1073/pnas.2208717119

Here we present the first elucidation of the disordered structure of ice VII, the dominant high-pressure form of water, at 2.2 GPa and 298 K from both single-crystal and powder neutron diffraction techniques. We reveal the three-dimensional atomic distributions from the maximum entropy method and unexpectedly find a ring-like distribution of hydrogen in contrast to the commonly-accepted discrete sites. In addition, total scattering analysis at 274 K clarified the difference in the intermolecular structure from ice VIII, the ordered counterpart of ice VII, despite an identical molecular geometry. Our complementary structure analyses robustly demonstrate the unique disordered structure of ice VII. Furthermore, these noble findings are related to the proton dynamics which drastically vary with pressure, and will contribute to an understanding of the structural origin of anomalous physical properties of ice VII under pressures.

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Research and development on membrane IS process for hydrogen production using solar heat

Myagmarjav, O.; Iwatsuki, Jin; Tanaka, Nobuyuki; Noguchi, Hiroki; Kamiji, Yu; Ioka, Ikuo; Kubo, Shinji; Nomura, Mikihiro*; Yamaki, Tetsuya*; Sawada, Shinichi*; et al.

International Journal of Hydrogen Energy, 44(35), p.19141 - 19152, 2019/07

https://doi.org/10.1016/j.ijhydene.2018.03.132

Radiation response of silicon carbide metal-oxide-semiconductor transistors in high dose region

Oshima, Takeshi; Yokoseki, Takashi; Murata, Koichi; Matsuda, Takuma; Mitomo, Satoshi; Abe, Hiroshi; Makino, Takahiro; Onoda, Shinobu; Hijikata, Yasuto*; Tanaka, Yuki*; et al.

Japanese Journal of Applied Physics, 55(1S), p.01AD01_1 - 01AD01_4, 2016/01

https://doi.org/10.7567/JJAP.55.01AD01

Nanoparticle formation by pulsed laser ablation of TiO

Yamaki, Tetsuya; Ito, Hisayoshi; Matsubara, Masakazu*; Abe, Hiroaki*; Asai, Keisuke*

Transactions of the Materials Research Society of Japan, 28(3), p.879 - 882, 2003/10

Titanium oxide nanoparticles were formed by pulsed laser ablation of a TiO rutile pellet with a KrF excimer laser ( = 248 nm). The ablation was performed in atmospheres of Ar and O at total pressures ranging from 0.2 and 10 Torr. At a higher pressure than 1 Torr, Ti in the nanoparticles had an oxidation state of 4+ to form TiO. According to the X-ray diffraction analyses, the nanopartiles were found to contain both the anatase and rutile phases, which crystallized through extremely energetic, non-equilibrium reactions in an ablation plume. In contrast, at pressures of 0.2 and 0.5 Torr, the nanoparticles were composed of dominant TiO with a small amount of a less oxidized phase such as TiO. The important result is that the XRD patterns of the samples prepared at 1 and 5 Torr showed the different anatase-to-rutile ratio of the peak intensities. This indicates that the weight fraction of the rutile/anatase crystalline phases can be controlled by the ambient gas pressure.

Japanese Contributions to IAEA INTOR Workshop,Phase 2A; Chapte VII:Impurity Control and First Wall-Engineering

; ; ; Nakamura, H.; ; ; ; ; ; *; et al.

JAERI-M 82-174, 309 Pages, 1982/11

JAERI-M-82-174.pdf:5.54MB

no abstracts in English

Preparation and evaluation of reference materials (LSD spikes), 2; Evaluation

Sumi, Mika; Takamatsu, Mai*; Ebisawa, Noriyuki; Abe, Katsuo; Kageyama, Tomio; Chiba, Masahiko; Nakazawa, Hiroaki; Suzuki, Toru; Katchi, Tomokazu*; Kushigeta, Yoshiyuki*; et al.

no journal, , 

Standard material which called Large Size Dried (LSD) spikes is required for Plutonium and Uranium measurement by Isotope Dilution Mass Spectrometry (IDMS). Collaboration work between JAEA and JNFL is performed to validate efficient use of standard material (primary) and to evaluate the effectivity of the Pu which separated and purified from MOX stored at JAEA. According to the presentation "Preparation and evaluation of reference materials (LSD spikes) (1) Preparation and testing", uncertainty of the actual sample measurements at Rokkasho Reprocessing plant are evaluated with GUM. Also, the effectivity of the half sized LSD spikes from generally used at JAEA and LSD spikes which prepared from Pu purified from MOX at JAEA are statistically evaluated and validated.

Preparation and evaluation of reference materials (LSD spikes), 1; Preparation and testing

Katchi, Tomokazu*; Kushigeta, Yoshiyuki*; Murakami, Yoshiki*; Hishi, Tomoyuki*; Ai, Hironobu*; Takamatsu, Mai*; Ebisawa, Noriyuki; Sumi, Mika; Abe, Katsuo; Kageyama, Tomio; et al.

no journal, , 

Standard material which called Large Size Dried (LSD) spikes is required for Plutonium and Uranium measurement by Isotope Dilution Mass Spectrometry (IDMS). Collaboration work between JAEA and JNFL is performed to validate efficient use of standard material (primary) and to evaluate the effectivity of the Pu which separated and purified from MOX stored at JAEA. Preparation of the LSD spikes at JAEA and evaluation with actual samples with remote operation systems at JNFL will be presented.

Overview and current construction state of J-PARC high-pressure neutron diffractometer PLANET

Hattori, Takanori; Arima, Hiroshi; Abe, Jun; Sano, Asami; Utsumi, Wataru; Nagai, Takaya*; Kagi, Hiroyuki*; Iitaka, Toshiaki*; Katayama, Yoshinori; Inoue, Toru*; et al.

no journal, , 

The new beamline dedicated to high-pressure studies, PLANET is now being constructed at BL11 in MLF/J-PARC. The design concept and the current construction state are introduced. The most characteristic feature of this beamline is a huge press with the maximum load of 1500 ton. The coupling this with the state of the art neutron techniques reveals hydrogen positions and its effects on the physical properties of materials and minerals at tens of gigapascals and a few thousand Kelvins. This opens the door to explore deep interior of the hydrous Earth and Planets.

Here comes first beam in high-pressure neutron diffractometer PLANET

Hattori, Takanori; Arima, Hiroshi; Sano, Asami; Abe, Jun; Utsumi, Wataru; Nagai, Takaya*; Kagi, Hiroyuki*; Iitaka, Toshiaki*; Katayama, Yoshinori; Inoue, Toru*; et al.

no journal, , 

The high-pressure neutron diffractometer PLANET is the new spectrometer dedicated for high-pressure experiments, which is now being constructed in MLF at J-PARC. The main purpose is to investigate the effect of the water on the Earth's dynamics with the help of the neutron. One of the most characteristic features is the huge 6ram 6axes press with the maximum centric load to 3000 tonf, which enables us to investigate the structure of crystals, liquids and amorphous solids under high-pressure and high-temperature conditions of 30GPa and 2000K. We have installed several optical devices, such as choppers, supermirror guides, 4-dimensional slit, and data acquisition system. On the last March, we received FIRST NEUTRON BEAM. In the talk, we overview the spectrometer and introduce the current construction state.