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Journal Articles

Intercalative and non-intercalative photo-recharge using all-solid-state cells for solar energy conversion and storage

Yoshimoto, Masataka*; Tamura, Kazuhisa; Watanabe, Kenta*; Shimizu, Keisuke*; Horisawa, Yuhei*; Kobayashi, Takeshi*; Tsurita, Hanae*; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*

Sustainable Energy & Fuels (Internet), 8(6), p.1236 - 1244, 2024/03

Photo-rechargeable systems, which can efficiently convert and store solar energy into chemical energy within single devices, are essential to harness sunlight effectively. Photo-(de)intercalation plays a pivotal role in the functionality of photorechargeable systems. Nevertheless, the photo-(de)intercalation process has not been conclusively confirmed owing to potential interference from side reactions, such as the decomposition of liquid electrolytes and the elution of electrode materials. In this study, we successfully demonstrated photo-responsive Li$$^{+}$$-deintercalation using an all-solid-state thin-film battery comprised of epitaxially-grown anatase TiO$$_{2}$$ doped with Nb (a-TiO$$_{2}$$:Nb) as the cathode. Under light irradiation, Li$$^{+}$$-deintercalation occurred and was subsequently reversibly intercalated into a-TiO$$_{2}$$:Nb during discharge.

Journal Articles

Stable photoelectrochemical reactions at solid/solid interfaces toward solar energy conversion and storage

Watanabe, Kenta*; Horisawa, Yuhei*; Yoshimoto, Masataka*; Tamura, Kazuhisa; Suzuki, Kota*; Kanno, Ryoji*; Hirayama, Masaaki*

Nano Letters, 24(6), p.1916 - 1922, 2024/02

Electrochemistry has extended from reactions at solid/liquid interfaces to those at solid/solid interfaces. In this study, we achieve the stable photoelectrochemical reaction at the semiconductor-electrode/solid-electrolyte interface in Nb-doped anatase-TiO$$_{2}$$ (a-TiO$$_{2}$$:Nb)/Li$$_{3}$$PO$$_{4}$$ (LPO)/Li all-solid-state cell. The oxidative currents of a-TiO$$_{2}$$:Nb/LPO/Li increase upon light irradiation when a-TiO$$_{2}$$:Nb is located at a potential that is more positive than its flat-band potential. The photoelectrochemical reaction at the semiconductor/solid-electrolyte interface is driven by the same principle as that at semiconductor/liquid-electrolyte interfaces. Thus, we extend photoelectrochemistry to all-solid-state systems composed of solid/solid interfaces.

Journal Articles

Exhumation history of the Kurobe area, Hida Range, based on solidification ages and depths of the Pliocene-Quaternary plutons

Sueoka, Shigeru; Kawakami, Tetsuo*; Suzuki, Kota*; Kagami, Saya; Yokoyama, Tatsunori; Shibazaki, Bunichiro*; Nagata, Mitsuhiro; Yamazaki, Ayu*; Higashino, Fumiko*; King, G. E.*; et al.

Fisshion, Torakku Nyusureta, (36), p.1 - 3, 2023/12

no abstracts in English

Journal Articles

Reducing the effect of noise generated from stepper motor for H0 collimator in J-PARC RCS

Fujiyama, Hiroki*; Takahashi, Hiroki; Okabe, Kota; Ito, Yuichi*; Hatakeyama, Shuichiro; Suzuki, Takahiro*; Otsu, Satoru*; Yamakawa, Ryuto*

Proceedings of 19th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.529 - 531, 2023/01

Stepper motors are used for mechanical drive in collimators and wire scanner monitors of J-PARC accelerators. Many of these drive unit hardware have been used since the beginning of J-PARC construction, and it is necessary to take measures against aging deterioration. Therefore, we started updating the motor and control system from around 2017. However, when the stepper motor was updated to the current product in the RCS H0 collimator, a malfunction occurred. This is because the drive unit control system cannot correctly recognize the state of the LS (limit switch) due to the noise generated by the motor driver, which hinders the operation. When the noise generated from the old and new stepper motors was measured in a simple test environment for confirmation, it was found that the current product was clearly larger. As a countermeasure, when the wiring of the stepper motor, which was bundled in a single multi-core cable, was separated into separate cables for the power system and LS signal system, the noise level was reduced to about 1/10 and normal operation was restored. I was able to. In this case, we report on noise countermeasures for the RCS H0 collimator drive unit.

Journal Articles

Designs and neutronic characteristics of an epithermal neutron moderator at ambient temperature for neutron time-of-flight measurements

Lee, J.; Ito, Fumiaki*; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Koizumi, Mitsuo

Journal of Nuclear Science and Technology, 59(12), p.1546 - 1557, 2022/12

 Times Cited Count:3 Percentile:86.35(Nuclear Science & Technology)

Journal Articles

Response characteristics of a lithium glass scintillator for gamma-ray and neutron

Lee, J.; Ito, Fumiaki*; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Koizumi, Mitsuo; Hori, Junichi*; Terada, Kazushi*

Dai-43-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2022/11

no abstracts in English

Journal Articles

Oxygen reduction activity and interfacial structures of La$$_{0.8}$$Sr$$_{0.2}$$CoO$$_{3}$$ at initial electrochemical process in an alkaline solution

Matsuzaki, Akira*; Hirayama, Masaaki*; Oguchi, Shoya*; Komo, Mamoru*; Ikezawa, Atsunori*; Suzuki, Kota*; Tamura, Kazuhisa; Arai, Hajime*; Kanno, Ryoji*

Electrochemistry (Internet), 90(10), p.107001_1 - 107001_8, 2022/10

 Times Cited Count:0 Percentile:0.01(Electrochemistry)

Oxygen reduction and evolution reactions (ORR and OER) of perovskite-type La$$_{0.8}$$Sr$$_{0.2}$$CoO$$_{3}$$ were characterized using two-dimensional model electrodes with different reaction planes. Synthesized by pulsed laser deposition, these thin and flat electrodes can reveal the reaction plane dependence of the ORR activity. From steady-state polarization measurements in KOH (aq.), the ORR activity was the highest on the (001) film during the first ORR/OER cycle, and it decreased significantly during the second cycle. In-situ synchrotron X-ray diffraction clarified crystal structure changes in the bulk and surface regions of La$$_{0.8}$$Sr$$_{0.2}$$CoO$$_{3}$$, and these changes are associated with forming oxygen defects during the initial electrochemical process. Furthermore, the La$$_{0.8}$$Sr$$_{0.2}$$CoO$$_{3}$$ surface partially decomposed upon reacting. Therefore, the interfacial structures formed in the electrochemical reaction field is important for enhancing ORR and OER activities.

Journal Articles

Solidification pressures and ages recorded in mafic microgranular enclaves and their host granite; An Example of the world's youngest Kurobegawa granite

Suzuki, Kota*; Kawakami, Tetsuo*; Sueoka, Shigeru; Yamazaki, Ayu*; Kagami, Saya; Yokoyama, Tatsunori; Tagami, Takahiro*

Island Arc, 31(1), p.e12462_1 - e12462_15, 2022/09

 Times Cited Count:1 Percentile:37.23(Geosciences, Multidisciplinary)

Journal Articles

Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation

Yamamoto, Kazami; Kinsho, Michikazu; Hayashi, Naoki; Saha, P. K.; Tamura, Fumihiko; Yamamoto, Masanobu; Tani, Norio; Takayanagi, Tomohiro; Kamiya, Junichiro; Shobuda, Yoshihiro; et al.

Journal of Nuclear Science and Technology, 59(9), p.1174 - 1205, 2022/09

 Times Cited Count:3 Percentile:80.29(Nuclear Science & Technology)

In the Japan Proton Accelerator Research Complex, the purpose of the 3 GeV rapid cycling synchrotron (RCS) is to accelerate a 1 MW, high-intensity proton beam. To achieve beam operation at a repetition rate of 25 Hz at high intensities, the RCS was elaborately designed. After starting the RCS operation, we carefully verified the validity of its design and made certain improvements to establish a reliable operation at higher power as possible. Consequently, we demonstrated beam operation at a high power, namely, 1 MW. We then summarized the design, actual performance, and improvements of the RCS to achieve a 1 MW beam.

Journal Articles

Demonstration of a neutron resonance transmission analysis system using a laser-driven neutron source

Hironaka, Kota; Ito, Fumiaki*; Lee, J.; Koizumi, Mitsuo; Takahashi, Tone; Suzuki, Satoshi*; Yogo, Akifumi*; Arikawa, Yasunobu*; Abe, Yuki*

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

Neutron resonance transmission analysis (NRTA) is a method for non-destructive measurement of nuclear material by using a time-of-flight (TOF) technique with a pulsed neutron source. For NRTA system to carry out the short-distance TOF measurements with high resolutions, a short-pulsed neutron source is required. Laser-driven neutron sources (LDNSs) is very suitable as such a neutron source because of its short pulse width. Moreover, the compactness of the laser system is also expected due to the remarkable development of laser technology in recent years. In the present study, we have developed a technology for applying LDNS to the NRTA system and conducted the demonstration experiment using the LFEX laser at Osaka University to investigate the feasibility of the system. In this experiment, we successfully observed the neutron resonance peaks of indium and silver samples.

Journal Articles

Development of a neutron sintillator for a compact NRTA system

Ito, Fumiaki*; Lee, J.; Hironaka, Kota; Takahashi, Tone; Suzuki, Satoshi*; Hori, Junichi*; Terada, Kazushi*; Koizumi, Mitsuo

KURNS Progress Report 2020, P. 98, 2021/08

A compact Nuclear Resonance Transmission Analysis (NRTA) system using a Laser Driven Neutron Source (LDNS) has been developed as a part of the development of nuclear non-proliferation technology supported by the MEXT. In NRTA, the neutron energy emitted from a pulsed neutron source is measured using the time-of-flight (TOF) method. LDNS is of interest because of its short pulse width, which is necessary for accurate TOF measurements over short flight distances. In the short-distance TOF measurement, there will be a large gamma-ray background event due to the coincidence of the timing of the arrival of 2.2 MeV gamma-rays due to neutron capture on hydrogen in the moderator and the timing of the arrival of neutrons around the resonance energy. Since the LDNS is still under development, the neutron flux is not sufficient and it is desirable to use a detector with high detection efficiency. For these reasons, we have developed a detector with low efficiency to gamma-rays and high efficiency to neutrons (multilayer neutron detector). As one of the results of this year's experiments, we confirmed that the multilayer neutron detector have low sensitivity to gamma-rays.

Journal Articles

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

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

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 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$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.

Journal Articles

Reactions of the Li$$_{2}$$MnO$$_{3}$$ cathode in an all-solid-state thin-film battery during cycling

Hikima, Kazuhiro*; Hinuma, Yoyo*; Shimizu, Keisuke*; Suzuki, Kota*; Taminato, So*; Hirayama, Masaaki*; Masuda, Takuya*; Tamura, Kazuhisa; Kanno, Ryoji*

ACS Applied Materials & Interfaces, 13(6), p.7650 - 7663, 2021/02

 Times Cited Count:5 Percentile:59.17(Nanoscience & Nanotechnology)

We evaluated the structural change of the cathode material Li$$_{2}$$MnO$$_{3}$$ that was deposited as an epitaxial film with an (001) orientation in an all-solid-state battery. In case of the electrode with LiPO$$_{4}$$ coating. Experiments revealed a structural change to a high-capacity (activated) phase that proceeded gradually and continuously with cycling. The activated phase barely showed any capacity fading. We propose a mechanism of structural change with cycling: charging to a high voltage at a sufficiently low Li concentration typically induces irreversible transition to a phase detrimental to cycling that could, but not necessarily, be accompanied by the dissolution of Mn and/or the release of O into the electrolyte, while a gradual irreversible transition to an activated phase happens at a similar Li concentration under a lower voltage.

Journal Articles

Development of ${it spatiotemporal}$ measurement and analysis techniques in X-ray photoelectron spectroscopy; From NAP-HARPES to 4D-XPS

Toyoda, Satoshi*; Yamamoto, Tomoki*; Yoshimura, Masashi*; Sumida, Hirosuke*; Mineoi, Susumu*; Machida, Masatake*; Yoshigoe, Akitaka; Suzuki, Satoru*; Yokoyama, Kazushi*; Ohashi, Yuji*; et al.

Vacuum and Surface Science, 64(2), p.86 - 91, 2021/02

We have developed ${it spatiotemporal}$ measurement and analysis techniques in X-ray photoelectron spectroscopy. To begin with, time-division depth profiles of gate stacked film interfaces have been achieved by NAP-HARPES (Near Ambient Pressure Hard X-ray Angle-Resolved Photo Emission Spectroscopy) data. We then have promoted our methods to quickly perform peak fittings and depth profiling from time-division ARPES data, which enables us to realize 4D-XPS analysis. It is found that the traditional maximum entropy method (MEM) combined with Jackknife averaging of sparse modeling in NAP-HARPES data is effective to perform dynamic measurement of depth profiles with high precision.

Journal Articles

$$omega N$$ scattering length from $$omega$$ photoproduction on the proton near the reaction threshold

Ishikawa, Takatsugu*; Fujimura, Hisako*; Fukasawa, Hiroshi*; Hashimoto, Ryo*; He, Q.*; Honda, Yuki*; Hosaka, Atsushi; Iwata, Takahiro*; Kaida, Shun*; Kasagi, Jirota*; et al.

Physical Review C, 101(5), p.052201_1 - 052201_6, 2020/05

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:233 Percentile:99.74(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Reversible structural changes and high-rate capability of Li$$_{3}$$PO$$_{4}$$-modified Li$$_{2}$$RuO$$_{3}$$ for lithium-rich layered rocksalt oxide cathodes

Taminato, So*; Hirayama, Masaaki*; Suzuki, Kota*; Kim, K.-S.*; Tamura, Kazuhisa; Kanno, Ryoji*

Journal of Physical Chemistry C, 122(29), p.16607 - 16612, 2018/07

 Times Cited Count:8 Percentile:31.46(Chemistry, Physical)

Lithium-rich layered rocksalt oxides are promising cathode materials for lithium-ion batteries. We investigate the effects of surface modification by amorphous Li$$_{3}$$PO$$_{4}$$ on the structures and electrochemical reactions in the surface region of an epitaxial Li$$_{2}$$RuO$$_{3}$$(010) film electrode. Structural characterization using SXRD, HAXPES, and NR shows that surface modification by Li$$_{3}$$PO$$_{4}$$ resulted in the partial substitution of P for Li in the surface region of Li$$_{2}$$RuO$$_{3}$$. The modified (010) surface exhibits better rate capability at 20 C compared to the unmodified surface. ${it In situ}$ surface XRD confirmed that highly reversible structural changes occurred at the modified surface during lithium (de)intercalation. These results demonstrate that this surface modification stabilizes the crystal structure in the surface region, and it can improve the rate capability of lithium-rich layered rocksalt oxide cathodes.

Journal Articles

Report on a Workshop of the 23th Young Researchers Association, a Fukushima Daiichi Nuclear Power Plant tour and the 10th Conference of Students Association of the Japan Health Physics Society

Matsuyama, Tsugufumi*; Suzuki, Tatsuhiko*; Migita, Yukie; Ishii, Kota*; Ueno, Satoshi*

Hoken Butsuri, 52(3), p.226 - 230, 2017/09

no abstracts in English

Journal Articles

Potential for microbial H$$_{2}$$ and metal transformations associated with novel bacteria and archaea in deep terrestrial subsurface sediments

Hernsdorf, A. W.*; Amano, Yuki; Miyakawa, Kazuya; Ise, Kotaro; Suzuki, Yohei*; Anantharaman, K.*; Probst, A. J.*; Burstein, David*; Thomas, B. C.*; Banfield, J. F.*

ISME Journal, 11, p.1915 - 1929, 2017/03

AA2016-0002.pdf:2.21MB

 Times Cited Count:78 Percentile:95.93(Ecology)

To evaluate the potential for interactions between microbial communities and disposal systems, we explored the structure and metabolic function of a sediment-hosted subsurface ecosystem associated with Horonobe Underground Research Center, Hokkaido, Japan. Overall, the ecosystem is enriched in organisms from diverse lineages and many are from phyla that lack isolated representatives. The majority of organisms can metabolize H$$_{2}$$, often via oxidative [NiFe] hydrogenases or electron-bifurcating [FeFe] hydrogenases that enable ferredoxin-based pathways, including the ion motive Rnf complex. Many organisms implicated in H$$_{2}$$ metabolism are also predicted to catalyze carbon, nitrogen, iron, and sulfur transformations. Notably, iron-based metabolism was predicted in a bacterial lineage where this function has not been predicted previously and in an ANME-2d archaeaon that is implicated in methane oxidation. We infer an ecological model that links microorganisms to sediment-derived resources and predict potential impacts of microbial activity on H$$_{2}$$ accumulation and radionuclide migration.

Journal Articles

Study on the deterioration mechanism of layered rock-salt electrodes using epitaxial thin films; Li(Ni, Co, Mn)O$$_{2}$$ and their Zr-O surface modified electrodes

Abe, Machiko*; Iba, Hideki*; Suzuki, Kota*; Minamishima, Hiroaki*; Hirayama, Masaaki*; Tamura, Kazuhisa; Mizuki, Junichiro*; Saito, Tomohiro*; Ikuhara, Yuichi*; Kanno, Ryoji*

Journal of Power Sources, 345, p.108 - 119, 2017/03

 Times Cited Count:11 Percentile:39.06(Chemistry, Physical)

The surface structure of the Li(Ni, Co, Mn)O$$_{2}$$ electrode was studied during charge/discharge process using electrochemical methods and X-ray/Neutron scattering techniques. It was found that during charge/discharge process the coverage of spinel structure increased. The spinel structure has low electrochemical activity and is not involved in Li insertion/extraction. After the surface modification, it was found that the coverage of the spinel structure did not increase. Further, it was also found out that the Li concentration at the electrode/electrolyte interface increased.

196 (Records 1-20 displayed on this page)