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Journal Articles

Hydrogenation of $$L$$1$$_{2}$$-type AlNi$$_{3}$$ alloy at high pressure and temperature

Endo, Naruki*; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

Journal of Alloys and Compounds, 645(Suppl.1), p.S61 - S63, 2015/10

 Times Cited Count:0 Percentile:100(Chemistry, Physical)

Journal Articles

Design and performance of high-pressure PLANET beamline at pulsed neutron source at J-PARC

Hattori, Takanori; Sano, Asami; Arima, Hiroshi*; Komatsu, Kazuki*; Yamada, Akihiro*; Inamura, Yasuhiro; Nakatani, Takeshi; Seto, Yusuke*; Nagai, Takaya*; Utsumi, Wataru; et al.

Nuclear Instruments and Methods in Physics Research A, 780, p.55 - 67, 2015/04

 Times Cited Count:40 Percentile:1.21(Instruments & Instrumentation)

PLANET is a time-of-flight (ToF) neutron beamline dedicated to high-pressure and high-temperature experiments. The large six-axis multi-anvil high-pressure press designed for ToF neutron diffraction experiments enables routine data collection at high pressures and high temperatures up to 10 GPa and 2000 K, respectively. To obtain clean data, the beamline is equipped with the incident slits and receiving collimators to eliminate parasitic scattering from the high-pressure cell assembly. The high performance of the diffractometer for the resolution ($$Delta$$ $$d$$/$$d$$ $$sim$$ 0.6%) and the accessible $$d$$-spacing range (0.2-8.4 ${AA}$) together with low-parasitic scattering characteristics enables precise structure determination of crystals and liquids under high pressure and temperature conditions.

Journal Articles

Correlation of rates of tritium migration through porous concrete

Fukada, Satoshi*; Katayama, Kazunari*; Takeishi, Toshiharu*; Edao, Yuki; Kawamura, Yoshinori; Hayashi, Takumi; Yamanishi, Toshihiko

Fusion Science and Technology, 67(2), p.99 - 102, 2015/03

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Journal Articles

Observation of transient structural changes on hydrogen absorption process of LaNi$$_{4.75}$$Sn$$_{0.25}$$ by time resolved X-ray diffraction

Machida, Akihiko; Higuchi, Kensuke*; Katayama, Yoshinori; Sakaki, Koji*; Kim, H.*; Nakamura, Yumiko*

Nippon Kinzoku Gakkai-Shi, 79(3), p.124 - 130, 2015/03

 Times Cited Count:4 Percentile:66.57(Metallurgy & Metallurgical Engineering)

Structural changes on hydrogen absorption process of hydrogen absorbing alloy LaNi$$_{4.75}$$Sn$$_{0.25}$$ have been investigated by time-resolved X-ray diffraction measurements using synchrotron radiation source. We have found the transient intermediate phase between the solid solution and hydride phases of LaNi$$_{4.75}$$Sn$$_{0.25}$$ under non-equilibrium hydrogen pressure condition at room temperature. LaNi$$_{4.75}$$Sn$$_{0.25}$$ has transformed into the hydride through three phase co-existing state. The hydrogen content of the intermediate phase estimated from the unit cell volume is independent of the induced hydrogen gas pressure. The variation of lattice constants indicate that the hydrogen atoms are located at the La$$_{2}$$Ni$$_{2}$$(Ni,Sn)$$_{2}$$ octahedron and La$$_{2}$$(Ni,Sn)$$_{2}$$ tetrahedron in the intermediate phase.

Journal Articles

Nanoscale diffusion tracing by radioactive $$^{8}$$Li tracer

Ishiyama, Hironobu*; Jeong, S.-C.*; Watanabe, Yutaka*; Hirayama, Yoshikazu*; Imai, Nobuaki*; Miyatake, Hiroari*; Oyaizu, Mitsuhiro*; Katayama, Ichiro*; Osa, Akihiko; Otokawa, Yoshinori; et al.

Japanese Journal of Applied Physics, 53(11), p.110303_1 - 110303_4, 2014/11

 Times Cited Count:4 Percentile:82.21(Physics, Applied)

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

Researches on Ti-alloy hydrides under high pressure and high temperature with the aid of in-situ synchrotron radiation X-ray diffraction measurements

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

Materia, 53(3), p.94 - 99, 2014/03

no abstracts in English

Journal Articles

$$P$$-$$T$$ phase diagram and structural transformations of molten P$$_{2}$$O$$_{5}$$ under pressure

Brazhkin, V. V.*; Katayama, Yoshinori; Lyapin, A. G.*; Saito, Hiroyuki

Physical Review B, 89(10), p.104203_1 - 104203_4, 2014/03

 Times Cited Count:7 Percentile:60.14(Materials Science, Multidisciplinary)

The P$$_{2}$$O$$_{5}$$ compound is an archetypical glass-forming oxide. We present the in situ X-ray diffraction study of the pressure-temperature phase diagram of P$$_{2}$$O$$_{5}$$ and of the liquid P$$_{2}$$O$$_{5}$$ structure under high pressure up to 10 GPa. We found that structural transformation in the liquid P$$_{2}$$O$$_{5}$$ under pressure is unique and includes three stages: first, the disappearance of the intermediate range order of the melt together with a slow increase in the average first-coordination number $$<$$$$N$$$$_{1}$$$$>$$ (P-O and O-P neighbors) up to 4 GPa; second, the "normal" compression almost without structural modification at higher pressures up to 8-9 GPa; and, finally, the abrupt change of the short-range order structure of the liquid with the jumplike $$<$$$$N$$$$_{1}$$$$>$$ increase at 9-10 GPa.

Journal Articles

Ponded melt at the boundary between the lithosphere and asthenosphere

Sakamaki, Tatsuya*; Suzuki, Akio*; Otani, Eiji*; Terasaki, Hidenori*; Urakawa, Satoru*; Katayama, Yoshinori; Funakoshi, Kenichi*; Wang, Y.*; Hernlund, J. W.*; Ballmer, M. D.*

Nature Geoscience, 6(12), p.1041 - 1044, 2013/12

 Times Cited Count:91 Percentile:2.67(Geosciences, Multidisciplinary)

The bounday between Earth's rigid lighosphere and the underlying, ductile ashenosphere is marked by a distinct siseismic discontinuity. We measure the density, viscosity and structure of basaltic magmas using high-pressure and high-temperature experiments and in situ X-ray analysis under pressure of up to 5.5 GPa. We find that the magmas rapidly become denser with increasing presure and show a viscosity minimum near 4 GPa. Magma mobility determined by the density and viscosity data exhibits a peak at pressures corresponding to depths of 120-150 km, within the asthenosphere. The diminishing mobility of magma in Earth's asthenosphere as the mlets ascend could lead to excessive melt accumulation at depths of 80-100 km, at the lithosphere-asthenosphere boundary. It is concluded that the observed seismic discontinuity at the lithosphere-asthenosphere boundary records this accumulation of melt.

Journal Articles

Mechanical properties of full austenitic welding joint at cryogenic temperature for the ITER toroidal field coil structure

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.

Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10

 Times Cited Count:8 Percentile:37.16(Nuclear Science & Technology)

ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.

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:10 Percentile:51.12(Nanoscience & Nanotechnology)

Journal Articles

Formation of NaCl-type lanthanum monohydride under high pressure; Discovery of novel rare-earth metal hydride using synchrotron radiation X-ray and neutron

Machida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Oshita, Hidetoshi*; Ikeda, Kazutaka*; Otomo, Toshiya*

Hamon, 23(2), p.131 - 136, 2013/05

Recently, we have revealed formation of NaCl-type LaD using synchrotron radiation X-ray diffraction and neutron diffraction measurements under high pressure. Previously, we have found that LaH$$_2$$ decomposes into two phases,which have different hydrogen compositions, the H-poor and H-rich phases, at 11 GPa at room temperature by synchrotron radiation X-ray diffraction. Recent neutron diffraction measurements on LaD$$_2$$ confirmed the formation of a NaCl-type LaD as the D-poor phase. This is the first observation of a formation of the rare-earth metal monodeuteride. Present result indicates that that rare-earth metal can form a series of stoichiometric hydrides,such as mono-, di-, and trihydride with the fcc metal lattice.

Journal Articles

Formation of BCC TiFe hydride under high hydrogen pressure

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori

International Journal of Hydrogen Energy, 38(16), p.6726 - 6729, 2013/05

 Times Cited Count:9 Percentile:70.52(Chemistry, Physical)

Journal Articles

Pressure-driven liquid-liquid transformations and corresponding bizarre viscosity behavior

Brazhkin, V. V.*; Katayama, Yoshinori; Kanzaki, Masami*; Lyapin, A. G.*

Advances in Chemical Physics, Vol.152, p.29 - 50, 2013/04

In recent years, transformations in the melts of elementary substances and oxides have been found under high pressure. These transformations are accompanied by structural changes and variations in physical properties. In this work, structure and viscosity of Se, AsS, AsS, As$$_{2}$$S$$_{3}$$ and B$$_{2}$$O$$_{3}$$ were studied using synchrotron radiation. These substances exhibit changes in bonding in the crystalline state under high pressure. An X-ray diffraction measurements and falling sphere viscosity measurements using an X-ray radiography technique were carried out. Huge change in viscosity which accompanies structural change under compression was observed in each substance.

Journal Articles

Characteristic densities of low- and high-pressure liquid SnI$$_{4}$$

Fuchizaki, Kazuhiro*; Hamaya, Nozomu*; Katayama, Yoshinori

Journal of the Physical Society of Japan, 82(3), p.033003_1 - 033003_4, 2013/03

 Times Cited Count:9 Percentile:40.61(Physics, Multidisciplinary)

An in situ synchrotron X-ray absorption measurement was carried out to estimate the density of liquid SnI$$_{4}$$. The characteristic densities of the low- and high-pressure liquids were found to be 4.6-4.7 and 4.9-5.0 g/cm$$^{3}$$, respectively, and their region is separated at around 1.7 GPa. The difference in density, although a slight amount of 0.3-0.4 g/cm$$^{3}$$, strongly suggests the existence of a weak but discontinuous phase transition at that pressure between the two liquid regions.

Journal Articles

Structural and dynamical properties of water under high temperatures and pressures

Ikeda, Takashi; Katayama, Yoshinori

Teion Kagaku, 71, p.125 - 129, 2013/03

Although liquid water is one of the most abundant materials on earth and most familiar to all of us, the present understanding of liquid water exhibiting various interesting properties depending on the environment is still far from satisfactory. Hence, it is still one of main subjects in vast research fields including physics, chemistry, and biology. In this contribution, we first describe the structural and dynamical properties of water under high temperatures and pressures revealed by combining advanced first principles molecular dynamics simulations and in situ X-ray diffraction experiments. Then, the future prospects for investigating water under higher pressures and temperatures are summarized.

Journal Articles

Energy-dispersive X-ray diffraction study of liquid gallium under high pressure at elevated temperatures

Yagafarov, O.; Katayama, Yoshinori; Brazhkin, V. V.*; Lyapin, A. G.*; Saito, Hiroyuki

High Pressure Research, 33(1), p.191 - 195, 2013/01

 Times Cited Count:5 Percentile:55.5(Physics, Multidisciplinary)

Journal Articles

Phase diagram and equation of state of TiH$$_{2}$$ at high pressures and high temperatures

Endo, Naruki; Saito, Hiroyuki; Machida, Akihiko; Katayama, Yoshinori; Aoki, Katsutoshi

Journal of Alloys and Compounds, 546, p.270 - 274, 2013/01

 Times Cited Count:6 Percentile:55.73(Chemistry, Physical)

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:43.91(Chemistry, Multidisciplinary)

Journal Articles

Structure of water from ambient to 4 GPa revealed by energy-dispersive X-ray diffraction combined with empirical potential structure refinement modeling

Yamaguchi, Toshio*; Fujimura, Koji*; Uchi, Kazuya*; Yoshida, Koji*; Katayama, Yoshinori

Journal of Molecular Liquids, 176, p.44 - 51, 2012/12

 Times Cited Count:11 Percentile:54.78(Chemistry, Physical)

X-ray diffraction measurements in an energy-dispersive mode have been made on water under various thermodynamic conditions of 298 K/30 MPa, 473 K/30 MPa and 573 K/30 MPa on a laboratory X-ray diffractometer. All the X-ray structure factors as well as those of water already measured at 298 K/1 GPa, 473 K/0.35 GPa and 486 K/4 GPa by using synchrotron X-ray radiation were subjected to empirical potential structure refinement (EPSR) modeling to reveal the detailed hydrogen bonding features in terms of partial pair correlation function, coordination number and three-dimensional spatial density function as a function of temperature and pressure. It has been shown to what extent the tetrahedral hydrogen-bonded network of water is perturbed by pressure and temperature.

303 (Records 1-20 displayed on this page)