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Journal Articles

Hydrogen absorption and diffusion behaviors in cube-shaped palladium nanoparticles revealed by ambient-pressure X-ray photoelectron spectroscopy

Tang, J.*; Seo, O.*; Rivera Rocabado, D. S.*; Koitaya, Takanori*; Yamamoto, Susumu*; Namba, Yusuke*; Song, C.*; Kim, J.*; Yoshigoe, Akitaka; Koyama, Michihisa*; et al.

Applied Surface Science, 587, p.152797_1 - 152797_8, 2022/06

 Times Cited Count:6 Percentile:79.58(Chemistry, Physical)

The hydrogen absorption and diffusion mechanisms on cube-shaped Pd nanoparticles (NPs) which are important hydrogen-storage materials were studied using X-ray photoelectron spectroscopy and DFT calculations. In the surface region, hydrogen absorption showed almost similar behavior regardless of the NPs size. It was found that the octahedral sites are more favorable than the tetrahedral sites for hydrogen occupation. We also clarified that the hydrogen atoms absorbing on the smaller-sized Pd NPs diffuse to the subsurface more actively because of the weakened Pd-H bond by the surface disordering, which plays an important role in hydrogen adsorption at a low H$$_{2}$$ pressure.

Journal Articles

Hydrogen absorption and desorption on Rh nanoparticles revealed by ${it in situ}$ dispersive X-ray absorption fine structure spectroscopy

Song, C.*; Seo, O.*; Matsumura, Daiju; Hiroi, Satoshi*; Cui, Y.-T.*; Kim, J.*; Chen, Y.*; Tayal, A.*; Kusada, Kohei*; Kobayashi, Hirokazu*; et al.

RSC Advances (Internet), 10(34), p.19751 - 19758, 2020/05

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

Journal Articles

Pressure studies on the antiferromagnetic Kondo semiconductor Ce(Ru$$_{1-x}$$Rh$$_x$$)$$_2$$Al$$_{10}$$ (x = 0,0.1)

Tanida, Hiroshi*; Kitagawa, Kentaro*; Tateiwa, Naoyuki; Sera, Masafumi*; Nishioka, Takashi*

Physical Review B, 96(23), p.235131_1 - 235131_7, 2017/12

 Times Cited Count:1 Percentile:6(Materials Science, Multidisciplinary)

We have done high pressure experiments on Ce(Ru$$_{1-x}$$Rh$$_x$$)$$_2$$Al$$_{10}$$ (x = 0 and 0.1) to study pressure-induced phase transitions from the antiferromagnetic to paramagnetic state at $$P_c$$. Experimental data of the electrical resistivity suggest that the $$c$$-$$f$$ hybridization gap could be not necessary to form the unusual AFM order. The pressure effects on the magnetic susceptibility is also studied. We discuss a difference in the pressure response of the magnetic susceptibility based the electronic state between x = 0 and 0.1.

Journal Articles

Vibrational states of atomic hydrogen in bulk and nanocrystalline palladium studied by neutron spectroscopy

Kofu, Maiko; Hashimoto, Naoki*; Akiba, Hiroshi*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; Iida, Kazuki*; Nakamura, Mitsutaka; Yamamuro, Osamu*

Physical Review B, 96(5), p.054304_1 - 054304_7, 2017/08

 Times Cited Count:12 Percentile:58.67(Materials Science, Multidisciplinary)

The vibrational states of hydrogen atoms in bulk and nanocrystalline palladium were examined in a wide energy region $$0 le hbar omega le 300$$ meV using neutron spectroscopy. In bulk PdH$$_{0.73}$$, the vibrational excitations of H atoms were roughly reproduced by the quantum harmonic oscillator (QHO) model. In PdH$$_{0.42}$$ nanocrystals with a diameter of 8 nm, however, additional vibrational excitations were found at energies above 80 meV. The energies and intensities of the additional states were not explained by QHO but reasonably described as vibrations in a highly anharmonic trumpet-like potential. The additional excitations are attributed to the vibrations of H atoms at tetrahedral sites in the subsurface region stabilized by surface effects. This is an experimental work which clearly detects hydrogen vibration ${it inside}$ metal nanoparticles.

Journal Articles

Radioactivity decontamination in and around school facilities in Fukushima

Saegusa, Jun; Tagawa, Akihiro; Kurikami, Hiroshi; Iijima, Kazuki; Yoshikawa, Hideki; Tokizawa, Takayuki; Nakayama, Shinichi; Ishida, Junichiro

Mechanical Engineering Journal (Internet), 3(3), p.15-00609_1 - 15-00609_7, 2016/06

After the Fukushima nuclear accident, JAEA lead off demonstration tests to find out effective decontamination methods for various school facilities in Fukushima. It included (1) dose reduction measures at schoolyards, (2) purification of swimming pool water and (3) removal of surface contamination of playground equipments. Through these tests, they established practical methods suitable for each situation; (1) At school yards, dose rates were drastically reduced by removing topsoil which was then placed in trenches of 1 m deep; (2) For the purification of pool water, the flocculation-coagulation treatment was found to be effective for collecting radiocesium dissolved in the water; (3) Demonstration tests for playground equipments, such as horizontal bars and a sandbox wood frame, suggested that effectiveness of decontamination considerably varied depending on the material, paint or coating condition. This paper reviews these demonstrations.

Journal Articles

$$^{61}$$Ni synchrotron radiation-based M$"o$ssbauer spectroscopy of nickel-based nanoparticles with hexagonal structure

Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Hosoi, Kohei*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; et al.

Scientific Reports (Internet), 6, p.20861_1 - 20861_8, 2016/02

 Times Cited Count:8 Percentile:41.01(Multidisciplinary Sciences)

Journal Articles

Radioactivity decontamination in and around school facilities in Fukushima

Saegusa, Jun; Tagawa, Akihiro; Kurikami, Hiroshi; Iijima, Kazuki; Yoshikawa, Hideki; Tokizawa, Takayuki; Nakayama, Shinichi; Ishida, Junichiro

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05

After the Fukushima nuclear accident, JAEA lead off demonstration tests to find out effective decontamination methods for various school facilities in Fukushima. It included (1) dose reduction measures at schoolyards, (2) purification of swimming pool water and (3) removal of surface contamination of playground equipments. Through these tests, they established practical methods suitable for each situation; (1) At school yards, dose rates were drastically reduced by removing topsoil which was then placed in trenches of 1 m deep; (2) For the purification of pool water, the flocculation-coagulation treatment was found to be effective for collecting radiocesium dissolved in the water; (3) Demonstration tests for playground equipments, such as horizontal bars and a sandbox wood frame, suggested that effectiveness of decontamination considerably varied depending on the material, paint or coating condition. This paper reviews these demonstrations.

Journal Articles

Organic solvent-free water-developable sugar resist material derived from biomass in green lithography

Takei, Satoshi*; Oshima, Akihiro*; Ichikawa, Takumi*; Sekiguchi, Atsushi*; Kashiwakura, Miki*; Kozawa, Takahiro*; Tagawa, Seiichi*; Oyama, Tomoko; Ito, Shoji*; Miyasaka, Hiroshi*

Microelectronic Engineering, 122, p.70 - 76, 2014/06

 Times Cited Count:23 Percentile:76.96(Engineering, Electrical & Electronic)

Biomass-derived branched sugar resist material was developed for environmentally-friendly electron beam lithography (EBL). The developed resist enables organic solvent-free water-developable process. The resist performance was evaluated using 75 keV EBL system. Lines of 50-200 nm were fabricated with high sensitivity of 7 $$mu$$C/cm$$^{2}$$. The resist is developable in pure water at 23 $$^{circ}$$C for 60 s, and it has acceptable CF$$_{4}$$ etch selectivity.

Journal Articles

Study on chemical reactivity control of sodium by suspended nanoparticles, 1

Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nagai, Masahiko*; Yoshioka, Naoki*

Journal of Nuclear Science and Technology, 47(12), p.1165 - 1170, 2010/12

 Times Cited Count:11 Percentile:59.27(Nuclear Science & Technology)

A study on the chemical reactivity control of sodium utilizing the atomic interaction of sodium with suspended nanoparticles was carried out. The atomic interaction between nanoparticles and sodium atoms were estimated by theoretical calculations and verified by fundamental physical properties measurements. Results showed the atomic bond of the sodium atom and the nanoparticle atom was significantly larger than that of the sodium atoms, when the transition metals that have the property of large electronegativity are applied as nanoparticles. From the theoretical calculation results, it was suggested that charge transfer occurs from the sodium atom to the nanoparticle atom. The fundamental physical properties of sodium with suspended nanoparticles were examined in comparison with that of sodium to verify the change of the atomic interaction. From the experimental results, it became clear that the surface tension becomes larger and the evaporation rate becomes smaller. These changes in fundamental physical properties were measured to verify the stability of the atomic interaction under the conditions of wide temperature range and the phase transformation from solid phase to liquid phase.

Journal Articles

Study on chemical reactivity control of sodium by suspended nanoparticles, 2

Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nagai, Masahiko*; Yoshioka, Naoki*

Journal of Nuclear Science and Technology, 47(12), p.1171 - 1181, 2010/12

 Times Cited Count:10 Percentile:56.37(Nuclear Science & Technology)

A study was conducted on the control of the chemical reactivity of sodium utilizing the atomic interaction between sodium and nanoparticles. The authors reported in a previous paper that the atomic interaction between sodium and nanoparticles increases and has the potential to suppress chemical reactivity. In this paper, the authors examined the released reaction heat and the reaction behavior. As a result, it was confirmed that the released reaction heat and the reaction rate decreased. From the results of experimental studies, it is clear that the suppressions of chemical reactivity are caused by a change in the sodium evaporation rate and fundamental physical properties such as surface tension which originate in the change in the atomic interaction between sodium and nanoparticle atoms. The suppression of chemical reactivity applying to FBR coolant was estimated for the case of sodium combustion and sodium-water reaction. It was confirmed that the concept of suspending nanoparticles into sodium has high potential for the suppression of chemical reactivity. Applicability as coolant to the FBR was investigated, including not only the chemical reaction properties but also the aspects of heat transfer and operation.

Journal Articles

Study on chemical reactivity control of liquid sodium; Development of nano-fluid and its property and applicability to FBR plant

Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Nakano, Haruyuki*; Ogata, Kan*; Yoshioka, Naoki*

Proceedings of 16th International Conference on Nuclear Engineering (ICONE-16) (CD-ROM), 4 Pages, 2008/05

no abstracts in English

Journal Articles

Study on chemical reactivity control of liquid sodium; Research program

Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Oka, Nobuki*; Yoshioka, Naoki*

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 5 Pages, 2007/04

Liquid sodium is used as the coolant of the fast breeder reactor (FBR), because of its high thermal conductivity and wide temperature range of liquid. However the chemical reactivity with water and oxygen of sodium is very high. So an innovative technology to control the reactivity is desired. The purpose of this study is to reduce the chemical reactivity of liquid sodium by dispersing the nanometer-size metallic particles into liquid sodium. Sub-themes of this study are nanoparticles production, evaluation of reaction control of liquid sodium, and feasibility study to FBR. In this paper, we describe the research program of them.

Journal Articles

Variation in groundwater levels, pore pressures and crustal strain related to earthquakes in the upper granite and sedimentary formations in the area of western Tono, Japan

Azuma, Shunichi*; Ishii, Hiroshi*; Asai, Yasuhiro*; Kitagawa, Yuichi*; Wakita, Hiroshi*; Yamauchi, Tsuneo*; Asamori, Koichi

Geodynamics of Atotsugawa Fault System, p.173 - 179, 2007/00

no abstracts in English

Journal Articles

Investigation on collapse mechanism of super-deep vertical shaft

Sakurai, Shunsuke*; Shimizu, Norikazu*; Akutagawa, Shinichi*; Yoshida, Hidenori*; Sato, Toshinori; Yamachi, Hiroshi*

Doboku Gakkai Rombunshu, F, 62(4), p.662 - 673, 2006/12

Recent interests in the development of deep underground facilities have been drawing significant attention for the importance of vertical shafts at great depth. However, due to shrinkage of domestic coal production, any deep shafts in the order of 1000 m have not been constructed in more than 20 years. For the purposes of technical transfer and establishment of fundamentals for rational design method of vertical shafts, intensive literature review and interviews to engineers with relevant experiences were conducted. As the results, there are two distinctive modes of failure mechanism originated by the common cause, that is "takanuke" and lining failure due to unexpected earth pressure.

Journal Articles

Decrease in $$^{111}$$Cd knight shift in superconducting Cd$$_{2}$$Re$$_{2}$$O$$_{7}$$; Evidence for spin-singlet pairing

Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Kitagawa, Kentaro*; Murakawa, Hiroshi*; Ishida, Kenji*; Ono, Hiroyuki*; Kato, Masaki*; Yoshimura, Kazuyoshi*; Walstedt, R. E.

Journal of the Physical Society of Japan, 73(11), p.2940 - 2943, 2004/11

 Times Cited Count:7 Percentile:48.33(Physics, Multidisciplinary)

$$^{111}$$Cd NMR measurements have been performed in the superconducting (SC) state of the pyrochlore Cd$$_{2}$$Re$$_{2}$$O$$_{7}$$ at T$$_{c}$$ $$sim$$ 1 K, and in a field of less than 3 kOe below $$T_{c}$$. The upper critical field at 0.1 K has been determined to be 4 kOe from in situ measurements of the ac susceptibility. A reduction of the Knight shift in the SC state is confirmed. The present results provide strong evidence that this compound has a singlet SC pairing symmetry.

Journal Articles

Economic scale of utilization of radiation, 1; Industry: Comparison between Japan and the U. S. A.

Makuuchi, Keizo; Tagawa, Seiichi*; Kashiwagi, Masayuki*; Kamada, Toshimitsu*; Sekiguchi, Masayuki*; Hosobuchi, Kazunari*; Tominaga, Hiroshi*; Ooka, Norikazu

Journal of Nuclear Science and Technology, 39(9), p.1002 - 1007, 2002/09

 Times Cited Count:6 Percentile:39.58(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Economic scale of utilization of nuclear

Takehisa, Masaaki*; Tagawa, Seiichi*; Kashiwagi, Masayuki*; Tominaga, Hiroshi*; Ishikawa, Isamu*; Ooka, Norikazu; Kamada, Toshimitsu*; Hosobuchi, Kazunari*; Makuuchi, Keizo; Takeshita, Hidefumi; et al.

Genshiryoku Riyo No Keizai Kibo; NSA/Commentaries, No.9, 139 Pages, 2001/01

no abstracts in English

Journal Articles

Studies on ion beam microdosimetry

Namba, Hideki; Aoki, Yasushi; Shibata, Hiromi*; Yoshida, Yoichi*; Side, Y.*; Tagawa, S.*; Nagai, Shiro; Watanabe, Hiroshi

Tokyo Daigaku Genshiryoku Kenkyusho Sogo Senta Heisei-Gan-Nendo Jushosha Kanribu Nempo, p.21 - 23, 1989/00

no abstracts in English

Oral presentation

Study on chemical reactivity control of liquid sodium, 2; Progress and research program of elemental technology

Saito, Junichi; Ara, Kuniaki; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Yamauchi, Miho*; Yamashita, Akihiro*; Oka, Nobuki*; Yoshioka, Naoki*

no journal, , 

no abstracts in English

Oral presentation

Study on chemical reactivity control of liquid sodium, 1; Research program of project

Ara, Kuniaki; Saito, Junichi; Sugiyama, Kenichiro*; Kitagawa, Hiroshi*; Ogata, Hiroshi*; Toda, Mikio*; Yoshioka, Naoki*

no journal, , 

no abstracts in English

28 (Records 1-20 displayed on this page)