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Journal Articles

Rotation of complex ions with ninefold hydrogen coordination studied by quasielastic neutron scattering and first-principles molecular dynamics calculations

Omasa, Yoshinori*; Takagi, Shigeyuki*; Toshima, Kento*; Yokoyama, Kaito*; Endo, Wataru*; Orimo, Shinichi*; Saito, Hiroyuki*; Yamada, Takeshi*; Kawakita, Yukinobu; Ikeda, Kazutaka*; et al.

Physical Review Research (Internet), 4(3), p.033215_1 - 033215_9, 2022/09

Journal Articles

Neutron diffraction study on the deuterium composition of nickel deuteride at high temperatures and high pressures

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

Physica B; Condensed Matter, 587, p.412153_1 - 412153_6, 2020/06

 Times Cited Count:2 Percentile:16.85(Physics, Condensed Matter)

The site occupancy of deuterium (D) atoms in face-centered-cubic nickel (fcc Ni) was measured along a cooling path from 1073 to 300 K at an initial pressure of 3.36 GPa via in situ neutron powder diffraction. Deuterium atoms predominantly occupy the octahedral (O) sites and slightly occupy the tetrahedral (T) sites of the fcc metal lattice. The O-site occupancy increases from 0.4 to 0.85 as the temperature is lowered from 1073 to 300 K. Meanwhile, the T-site occupancy remains c.a. 0.02. The temperature-independent behavior of the T-site occupancy is unusual, and its process is not yet understood. From the linear relation between the expanded lattice volume and D content, a D-induced volume expansion of 2.09(13) ${AA $^{3}$/D}$ atom was obtained. This value is in agreement with the values of 2.14-2.2 ${AA $^{3}$/D}$ atom previously reported for Ni and Ni$$_{0.8}$$ Fe$$_{0.2}$$ alloy.

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:2 Percentile:13.06(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

Hexagonal close-packed iron hydride behind the conventional phase diagram

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

Scientific Reports (Internet), 9(1), p.12290_1 - 12290_9, 2019/08

 Times Cited Count:20 Percentile:82.13(Multidisciplinary Sciences)

Hexagonal close-packed iron hydride, hcp FeHx, is absent from the conventional phase diagram of the Fe-H system, although hcp metallic Fe exists stably over extensive temperature ($$T$$) and pressure ($$P$$) conditions, including those corresponding to the Earth's inner core. ${{it In situ}}$ X-ray and neutron diffraction measurements at temperatures ranging from 298 to 1073 K and H pressures ranging from 4 to 7 GPa revealed that the hcp hydride was formed for FeH$$_{x}$$ compositions when $$x < 0.6$$. Hydrogen atoms occupied the octahedral interstitial sites of the host metal lattice both partially and randomly. The hcp hydride exhibited a H-induced volume expansion of 2.48(5) $AA $^{3}$$/H-atom, which was larger than that of the face-centered cubic (fcc) hydride. The hcp hydride showed an increase in $$x$$ with $$T$$, whereas the fcc hydride showed a corresponding decrease. The present study provides guidance for further investigations of the Fe-H system over an extensive $$x$$-$$T$$-$$P$$ region.

Journal Articles

True Boundary for the formation of homoleptic transition-metal hydride complexes

Takagi, Shigeyuki*; Iijima, Yuki*; Sato, Toyoto*; Saito, Hiroyuki; Ikeda, Kazutaka*; Otomo, Toshiya*; Miwa, Kazutoshi*; Ikeshoji, Tamio*; Aoki, Katsutoshi*; Orimo, Shinichi*

Angewandte Chemie; International Edition, 54(19), p.5650 - 5653, 2015/05

 Times Cited Count:30 Percentile:68.62(Chemistry, Multidisciplinary)

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:46 Percentile:83.89(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

Li$$_{4}$$FeH$$_{6}$$; Iron-containing complex hydride with high gravimetric hydrogen density

Saito, Hiroyuki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Iijima, Yuki*; Endo, Naruki*; Aoki, Katsutoshi*; Orimo, Shinichi*

APL Materials (Internet), 2(7), p.076103_1 - 076103_7, 2014/07

 Times Cited Count:23 Percentile:69.69(Nanoscience & Nanotechnology)

Journal Articles

Syntheses of novel metal hydrides under high pressure and high pressure with the aid of ${it in-situ}$ synchrotron radiation X-ray diffraction measurement

Saito, Hiroyuki; Takagi, Shigeyuki*; Aoki, Katsutoshi; Orimo, Shinichi*

Hoshako, 27(1), p.10 - 19, 2014/01

no abstracts in English

Journal Articles

Improvement effects of TiCl$$_{3}$$ on dehydrogenation of magnesium borohydride Mg(BH$$_{4}$$)$$_{2}$$

Li, H.-W.*; Matsumura, Daiju; Nishihata, Yasuo; Akiba, Etsuo*; Orimo, Shinichi*

Nihon Kinzoku Gakkai-Shi, 77(12), p.627 - 630, 2013/12

 Times Cited Count:4 Percentile:28.73(Metallurgy & Metallurgical Engineering)

no abstracts in English

Journal Articles

Synthesis and formation process of Al$$_{2}$$CuH$$_{x}$$; A New class of interstitial aluminum-based alloy hydride

Saito, Hiroyuki; Takagi, Shigeyuki*; Endo, Naruki; Machida, Akihiko; Aoki, Katsutoshi; Orimo, Shinichi*; Katayama, Yoshinori

APL Materials (Internet), 1(3), p.032113_1 - 032113_7, 2013/09

 Times Cited Count:14 Percentile:53.45(Nanoscience & Nanotechnology)

Journal Articles

Unusual sevenfold coordination of Ru in complex hydride Na$$_{3}$$RuH$$_{7}$$; Prospect for formation of [FeH$$_{7}$$]$$^{3-}$$ anion

Takagi, Shigeyuki*; Ikeshoji, Tamio*; Matsuo, Motoaki*; Sato, Toyoto*; Saito, Hiroyuki; Aoki, Katsutoshi; Orimo, Shinichi*

Applied Physics Letters, 103(11), p.113903_1 - 113903_4, 2013/09

 Times Cited Count:9 Percentile:39.34(Physics, Applied)

Journal Articles

Formation process of perovskite-type hydride LiNiH$$_{3}$$; ${it In situ}$ synchrotron radiation X-ray diffraction study

Sato, Ryutaro*; Saito, Hiroyuki; Endo, Naruki; Takagi, Shigeyuki*; Matsuo, Motoaki*; Aoki, Katsutoshi; Orimo, Shinichi*

Applied Physics Letters, 102(9), p.091901_1 - 091901_4, 2013/03

 Times Cited Count:22 Percentile:67.85(Physics, Applied)

Journal Articles

Density-functional study of perovskite-type hydride LiNiH$$_{3}$$ and its synthesis; Mechanism for formation of metallic perovskite

Takagi, Shigeyuki*; Saito, Hiroyuki; Endo, Naruki; Sato, Ryutaro*; Ikeshoji, Tamio*; Matsuo, Motoaki*; Miwa, Kazutoshi*; Aoki, Katsutoshi; Orimo, Shinichi*

Physical Review B, 87(12), p.125134_1 - 125134_6, 2013/03

 Times Cited Count:11 Percentile:47.64(Materials Science, Multidisciplinary)

Journal Articles

Formation of an Fe-H complex anion in YFe$$_{2}$$; Adjustment of imbalanced charge by additional Li as an electron donor

Matsuo, Motoaki*; Saito, Hiroyuki; Machida, Akihiko; Sato, Ryutaro*; Takagi, Shigeyuki*; Miwa, Kazutoshi*; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Orimo, Shinichi*

RSC Advances (Internet), 3(4), p.1013 - 1016, 2013/01

 Times Cited Count:16 Percentile:48.31(Chemistry, Multidisciplinary)

Journal Articles

Experimental studies of complex hydride YMn$$_{2}$$H$$_{6}$$ on formation kinetics and X-ray absorption fine structure analyses

Matsuo, Motoaki*; Matsumura, Daiju; Nishihata, Yasuo; Li, G.*; Hiyama, Nao*; Semboshi, Satoshi*; Orimo, Shinichi*

Applied Physics Letters, 100(4), p.044101_1 - 044101_3, 2012/01

 Times Cited Count:3 Percentile:14.04(Physics, Applied)

Journal Articles

Correlation between structure of titanium additives and dehydrogenation reaction of magnesium borohydride studied by continuous observation of X-ray absorption spectroscopy

Matsumura, Daiju; Oyama, Takahiro*; Okajima, Yuka*; Nishihata, Yasuo; Li, H.-W.*; Orimo, Shinichi*

Materials Transactions, 52(4), p.635 - 640, 2011/04

 Times Cited Count:12 Percentile:55.86(Materials Science, Multidisciplinary)

Local structure of Ti-based additives in Mg(BH$$_{4}$$)$$_{2}$$ was studied by X-ray absorption fine structure spectroscopy with conventional and dispersive mode in order to understand the correlation between the structure of the additives and dehydrogenation property of Mg(BH$$_{4}$$)$$_{2}$$. Simultaneous measurement of the dehydrogenation curve and the X-ray absorption spectroscopy by the dispersive optics revealed that a part of TiCl$$_{3}$$ additive is converted to Ti$$_{x}$$Mg$$_{1-3x/2}$$(BH$$_{4}$$)$$_{2}$$ ($$x$$ = 0$$sim$$0.67) just after ball milling mixture and then promptly resolved to TiB$$_{2}$$ at 100-150$$^{circ}$$C with the first dehydrogenation peak. TiO$$_{2}$$ additive is slowly converted to lower oxidation state in wide temperature range around the second dehydrogenation peak at 350$$^{circ}$$C where the main dehydrogenation reaction of Mg(BH$$_{4}$$)$$_{2}$$ occurs.

Journal Articles

Hydrogen storage using aluminum hydride

Ikeda, Kazuki*; Orimo, Shinichi*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi

Suiso Seizo, Kyuzo, Chozo Zairyo To Anzenka, p.317 - 327, 2010/08

AlH$$_{3}$$ is a metal hydride with a large gravimetric and volumetric hydrogen content (10.1 wt.% and 149kgH$$_{2}$$/m$$^{3}$$, respectively), and therefore it is promising as a hydrogen storage material. The high capacity and low desorption temperature (80$$sim$$150$$^{circ}$$C) have attracted much attention. In situ X-ray diffraction measurements for the Al-H binary system at high pressures and temperatures were performed to investigate the hydrogenation of aluminum metal immersed in hydrogen fluid as well as the phase stability of the aluminum hydride formed.

Journal Articles

Multi-millijoule, nonlinear preamplifier for high intensity femtosecond Yb:YAG chirped-pulse amplification lasers at 1030 nm

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Nakai, Yoshiki; Orimo, Satoshi; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; et al.

Applied Physics B, 97(2), p.379 - 382, 2009/10

 Times Cited Count:7 Percentile:38.22(Optics)

We report the highest energy broadband laser pulses at a center wavelength of 1030 nm based on optical parametric chirped-pulse amplification (OPCPA). We have demonstrated amplification of 1030 nm femtosecond laser pulses from a broadband Yb oscillator to over 6.5 mJ with a total gain of greater than 10$$^{7}$$ achieved in a single pass through only 56 mm of gain material at a 10 Hz repetition rate. The amplified spectral bandwidth of 10.8 nm affords recompression to a 230 fs pulse duration following amplification. As an alternative to the regenerative amplifier (RA) this system is one of the more promising candidates for realizing compact, high intensity, direct diode pumped, high repetition rate femtosecond Yb:YAG chirped-pulse amplification (CPA) in laser systems.

Journal Articles

Application of laser-accelerated protons to the demonstration of DNA double-strand breaks in human cancer cells

Yogo, Akifumi; Sato, Katsutoshi; Nishikino, Masaharu; Mori, Michiaki; Teshima, Teruki*; Numasaki, Hodaka*; Murakami, Masao*; Demizu, Yusuke*; Akagi, Takashi*; Nagayama, Shinichi*; et al.

Applied Physics Letters, 94(18), p.181502_1 - 181502_3, 2009/05

 Times Cited Count:106 Percentile:94.66(Physics, Applied)

Journal Articles

Advanced neutron shielding material using zirconium borohydride and zirconium hydride

Hayashi, Takao; Tobita, Kenji; Nakamori, Yuko*; Orimo, Shinichi*

Journal of Nuclear Materials, 386-388, p.119 - 121, 2009/04

 Times Cited Count:74 Percentile:98.09(Materials Science, Multidisciplinary)

Neutron transport calculations have been carried out to assess the capability of zirconium borohydride (Zr(BH$$_{4}$$)$$_{4}$$) and zirconium hydride (ZrH$$_{2}$$) as advanced shield materials, because excellent shields can be used to protect outer structural materials from serious activation. The neutron shielding capability of Zr(BH$$_{4}$$)$$_{4}$$ is lower than ZrH$$_{2}$$, even though the hydrogen density of Zr(BH$$_{4}$$)$$_{4}$$ is slightly higher than that of ZrH$$_{2}$$. High-Z atoms are effective in neutron shielding as well as hydrogen atoms. The combination of steel and Zr(BH$$_{4}$$)$$_{4}$$ can improve the neutron shielding capability. The combinations of (Zr(BH$$_{4}$$)$$_{4}$$ + F82H) and (ZrH$$_{2}$$ + F82H) can reduce the thickness of the shield by 6.5% and 19% compared to (water + F82H), respectively. The neutron flux for Zr(BH$$_{4}$$)$$_{4}$$ is drastically reduced in the range of neutron energy below 100 eV compared to other materials, due to the effect of boron, which can lead to a reduction of radwaste from fusion reactors.

46 (Records 1-20 displayed on this page)