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Kawamura, Seiko; Hattori, Takanori; Harjo, S.; Ikeda, Kazutaka*; Miyata, Noboru*; Miyazaki, Tsukasa*; Aoki, Hiroyuki; Watanabe, Masao; Sakaguchi, Yoshifumi*; Oku, Takayuki
Neutron News, 30(1), p.11 - 13, 2019/05
In Japanese neutron scattering facilities, some SE equipment that are frequently used at an instrument, such as the closed-cycle refrigerator (CCR), have been prepared for the instrument as standard SE. They are operated for user experiments by the instrument group. The advantage of this practice is that they can optimize the design of the SE for the instrument and can directly respond to users' requests. On the other hand, the SE team in the Materials and Life Science Experimental Facility (MLF) in J-PARC has managed commonly used SE to allow neutron experiments with more advanced SE. In this report, recent SE in the MLF is introduced. Highlighted are the SE in BL11, BL19, BL21 and BL17 and other SE recently progressed by the SE team.
Torigoe, Shuhei*; Hattori, Takayuki*; Kodama, Katsuaki; Honda, Takashi*; Sagayama, Hajime*; Ikeda, Kazutaka*; Otomo, Toshiya*; Nitani, Hiroaki*; Abe, Hitoshi*; Murakawa, Hiroshi*; et al.
Physical Review B, 98(13), p.134443_1 - 134443_7, 2018/10
Times Cited Count：11 Percentile：52.03(Materials Science, Multidisciplinary)Kawamura, Seiko; Oku, Takayuki; Watanabe, Masao; Takahashi, Ryuta; Munakata, Koji*; Takata, Shinichi; Sakaguchi, Yoshifumi*; Ishikado, Motoyuki*; Ouchi, Keiichi*; Hattori, Takanori; et al.
Journal of Neutron Research, 19(1-2), p.15 - 22, 2017/11
Sample environment (SE) team at the Materials and Life Science Experimental Facility (MLF) in J-PARC has worked on development and operation of SE equipment and devices. All the members belong to one sub-team at least, such as Cryogenic and magnet, High temperature, High pressure, Soft matter and special environment including Pulse magnet, Hydrogen environment, Light irradiation and 
He spin filter. Cryostats, a magnet, furnaces, a VX-6-type Paris-Edinburgh press and a prototype of a Spin-Exchange Optical Pumping (SEOP) based He spin filter for polarized neutron beam experiments are in operation. Furthermore, a prototype of compact power supply for a pulsed magnet system is currently developed. In the J-PARC Research Building, several pieces of equipment for softmatter research such as a rheometer and a gas and vapor adsorption measurement instrument have been prepared.
Machida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi*; Oshita, Hidetoshi*; et al.
Physical Review Letters, 108(20), p.205501_1 - 205501_5, 2012/05
Times Cited Count：17 Percentile：67.41(Physics, Multidisciplinary)Hydrogen atoms absorbed in a metal occupy the interstitial sites of the metal lattice. In an fcc metal lattice, each metal atom has two tetrahedral (T) and one octahedral (O) sites that can accommodate hydrogen. Rare-earth metal La forms T-site occupied LaH
and fully occupied LaH
. O-site occupied or NaCl-type monohydride has yet to be reported for rare-earth metals. Previous X-ray diffraction measurements revealed the pressure-induced decomposition of an fcc-LaH
into H-rich and H-poor phases around 11 GPa. The present neutron diffraction measurements on LaD confirm the formation of NaCl-type LaD as a counterpart of the D-rich LaD
by disproportionation. First-principle calculations demonstrate that the NaCl-type LaH is stabilized at high pressures. Finding the NaCl-type LaH will pave the way for investigations on the site-dependent nature of hydrogen-metal interactions.
Shimojo, Fuyuki*; Miyata, Yasuhisa*; Sugahara, Takayuki*; Hattori, Takanori; Tsuji, Kazuhiko*
Journal of Physics; Conference Series, 98, p.042016_1 - 042016_4, 2008/00
Times Cited Count：0 Percentile：0.05(Metallurgy & Metallurgical Engineering)The structural and bonding properties of liquid InAs under pressure are investigated by ab initio molecular-dynamics simulations. The calculated structure factors are in good agreement with the recent X-ray diffraction measurements over a wide range of pressure. It is shown that the pressure dependence of the spatial correlation between atoms depends on the species of atomic pairs reflecting the strength of the covalent bonding. A detailed investigation of the pair distribution functions confirms that different pressure-induced structural changes occur below and above 6-10 GPa. It is suggested that such structural changes are related to the reduction of the covalent nature under pressure.
Hattori, Takanori; Tsuji, Kazuhiko*; Miyata, Yasuhisa*; Sugahara, Takayuki*; Shimojo, Fuyuki*
Physical Review B, 76(14), p.144206_1 - 144206_10, 2007/10
Times Cited Count：6 Percentile：31.31(Materials Science, Multidisciplinary)To understand the pressure-induced structural changes of liquid III-V compounds systematically, the pressure dependence of liquid InAs was investigated using the synchrotron X-ray diffraction and an 
molecular dynamics simulation (AIMD). The X-ray diffraction experiments revealed that the liquid changes its compression behavior from a nearly uniform type to a nonuniform one around 9 GPa. Corresponding to this change, the coordination number CN, which is maintained up to 9 GPa, markedly increases from 6.0 to 7.5. The AIMD simulation revealed that this change is related to the change in the pressure dependence of all three pair correlations. In particular, a marked change is observed in the As-As correlation; in the low pressure region the position of the first peak in 
, 
, increases with maintaining the CN
, but in the high pressure region the stops increasing and the CN begins to increase. The results for InAs are compared with those for GaSb and InSb and the systematics of the pressure-induced structural change of liquid III-V compounds are dicussed.
Nakai, Kunihiro*; Kai, Michiaki*; Okoshi, Minoru; Kato, Tomoko; Yamaguchi, Tetsuji; Sasaki, Takayuki*; Hattori, Takatoshi*; Miyazaki, Shinichiro*; Yoshizawa, Yuji*; Higuchi, Natsuko*; et al.
no journal, ,
no abstracts in English
Yoshizawa, Yuji*; Kai, Michiaki*; Okoshi, Minoru; Kato, Tomoko; Yamaguchi, Tetsuji; Sasaki, Takayuki*; Hattori, Takatoshi*; Miyazaki, Shinichiro*; Higuchi, Natsuko*; Tokonami, Shinji*; et al.
no journal, ,
no abstracts in English
Aoki, Katsutoshi; Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Komatsu, Kazuki*; Arima, Hiroshi; Otomo, Toshiya*; et al.
no journal, ,
Neutron diffraction measurements have revealed that LaD undergoes phase separation at high pressure with the relocation of deuterium atoms in the interstitial sites of La metal lattice. Deuterium atoms, which occupy the tetrahedral sites of the fcc metal lattice in LaD, move into the empty octahedral sites at 11 GPa to form LaD and LaD
both having fcc metal lattices. Mono-hydride with an NaCl structure, which is common for mono-hydrides of transition metals, is formed in rare-earth metals for the first time. The first-principle calculations showed that LaH is stable at low pressure and it undergoes a phase separation into LaH and LaH at 10 GPa, which is excellent agreement with the experimental results. Enthalpy comparison shows that unusual volume contraction in LaH than LaH explains the phase separation phenomena. Lattice dynamics calculations on these lanthanum hydrides shed light on the detailed mechanism.
Aoki, Katsutoshi; Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Komatsu, Kazuki*; Arima, Hiroshi; Otomo, Toshiya*; et al.
no journal, ,
Synchrotron X-ray and neutron diffraction measurements have revealed that LaD undergoes phase separation at high pressure with the relocation of deuterium atoms in the interstitial sites of La metal lattice. Synchrotron X-ray and neutron experiments were made at BL22XU, SPring-8 and a total scattering device, NOVA, J-PARC. Deuterium atoms, which occupy the tetrahedral sites of the fcc metal lattice in LaD, move into the empty octahedral sites at 11 GPa to form LaD and LaD both having fcc metal lattices. Mono-hydride with an NaCl structure, which is common for mono-hydrides of transition metals, is formed in rare-earth metals for the first time. The first-principle calculations showed that LaH is stable at low pressure and it undergoes a phase separation into LaH and LaH at 10 GPa, which is excellent agreement with the experimental results.
Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi; Oshita, Hidetoshi*; et al.
no journal, ,
Formation of an NaCl-type mono-deuteride LaD has been found by neutron diffraction experiments at high pressure. The NaCl-type structure has been reported for alkaline hydrides and transition metal hydrides, but not for rare-earth metal hydrides. The NaCl-type mono-hydride is formed in rare-earth metals for the first time. Lanthanum mono-deuteride is formed as a result of the phase separation of the di-deuteride under high pressure. This result suggests that the three different hydrides, mono-, di-, and tri-hydrides, with the fcc metal lattice are realized. The hydrogen atoms occupy only O-sites, only T-sites and both O-sites and T-sites in the mono-, di-, and tri-hydrides, respectively. Hence, it is expected that the H-M bonding nature is different for each hydride.
Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi; Oshita, Hidetoshi*; et al.
no journal, ,
We have investigated the pressure-induced phase separation in rare-earth metal dihydrides by synchrotron radiation X-ray diffraction and neutron diffraction experiments. Rare-earth metal hydrides exhibit the stoichiometoric dihydride and trihydride. The dihydride is a metallic while trihydride is an insulator. Recently, we have found the pressure induced phase separation in the lanthanum dihydride. This phenomenon is understood as the decomposition into the hydrogen-poor and rich phases under high pressure. However, the hydrogen occupancy and position have been unclear yet. Our neutron diffraction experiments have revealed that an NaCl-type mono-deuteride is formed as a counterpart of the deuterium-rich phase.
Aoki, Katsutoshi; Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Komatsu, Kazuki*; Arima, Hiroshi; Otomo, Toshiya*; et al.
no journal, ,
Rare-earth metal La forms T-site occupied fcc-LaH and fully occupied fcc-LaH, the former is metallic and the latter is insulating. Our previous synchrotron X-ray and infrared measurements revealed that the dihydride decomposed into hydrogen-rich and hydrogen-poor phases upon compression to 11 GPa at ambient temperature; the hydrogen rich phase was identified as LaH but the hydrogen composition and occupation sites of the hydrogen-poor phase remained undetermined. The crystal structure of the hydrogen-poor phase was investigated for LaD by neutron diffraction measurement with a total diffractometer NOVA at J-PARC. The formation of NaCl-type LaD as a counterpart of LaD by the decomposition was confirmed from the diffraction profiles. First-principle enthalpy and lattice dynamic calculations have demonstrated that the NaCl-type LaH is stabilized at high pressures.
Kakurai, Kazuhisa; Oku, Takayuki; Osakabe, Toyotaka; Hattori, Takanori; Noda, Yohei
no journal, ,
Machida, Akihiko; Hattori, Takanori; Honda, Mitsunori*; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi*; Oshita, Hidetoshi*; et al.
no journal, ,
We have investigated the structural properties of rare-earth metal hydrides under high pressure. LaH has the CaF type structure in which the H atoms locate at the tetrahedral interstitial sites (T-sites) of the fcc metal lattice. Synchrotron radiation X-ray diffraction and infrared reflection experiments revealed disproportionation reaction of LaH into the H-poor and H-rich phases around 11 GPa. Before the disproportionation reaction, we have found that the fcc metal lattice transformed into tetragonal lattice. The ordering of the H atoms in the octahedral-sites (O-sites) causes the tetragonal distortion of LaH. The tetragonal transformation and successive disproportionation reaction of LaH would closely relate to the inter-site transfer of the H atoms between the T- and O-sites. We have performed the neutron diffraction experiments of LaD to investigate the change of the positions and occupancies of the hydrogen atoms under high pressure.
Machida, Akihiko; Honda, Mitsunori*; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi*; Oshita, Hidetoshi*; et al.
no journal, ,
Hydrogen atoms absorbed in a metal occupy the interstitial sites of the metal lattice. In an fcc metal lattice, each metal atom has two tetrahedral (T) and one octahedral (O) sites that can accommodate hydrogen. Rare-earth metal La forms T-site occupied LaH and fully occupied LaH. Previous X-ray diffraction measurements revealed the pressure-induced decomposition of an fcc-LaH into H-rich and H-poor phases around 11 GPa. We performed the neutron diffraction measurements on LaD, and found the formation of NaCl-type LaD as a phase separation products. We have first found the NaCl-type rare-earth metal monohydride.
Aso, Tomokazu; Yamauchi, Yasuhiro; Sakaguchi, Yoshifumi*; Munakata, Koji*; Ishikado, Motoyuki*; Kawamura, Seiko; Yokoo, Tetsuya*; Watanabe, Masao; Takata, Shinichi; Hattori, Takanori; et al.
no journal, ,
In FY2013, the SE team was officially organized in Technology Development Section in MLF with succeeding the previous ad hoc SE team. We are working on operation of so-called beam-line (BL)-common SE equipment and development of the SE devices as well as the previous SE team. We have already prepared a vertical-field superconducting magnet, a dilution refrigerator insert, a furnace with Nb heater and 2K cryostat as the BL-common SE equipment. In this fiscal year, a bottom-loading type 
He cryostat will be introduced. Moreover, we have just started developing high pressure system by collaborating with High Pressure Group in MLF, to comply with users' requests. We have also discussed the general purpose of apparatus for pulse magnet and for hydrogen environment. We plan to prepare more working area for the SE equipment, whose number gradually increases, and sample preparation and characterization rooms for users in the new building, which is under construction.
Aso, Tomokazu; Yamauchi, Yasuhiro; Sakaguchi, Yoshifumi*; Munakata, Koji*; Ishikado, Motoyuki*; Kawamura, Seiko; Yokoo, Tetsuya*; Watanabe, Masao; Takata, Shinichi; Hattori, Takanori; et al.
no journal, ,
In FY2013, the SE team was officially organized in Technology Development Section in MLF with succeeding the previous ad hoc SE team. We are working on operation of so-called beam-line (BL)-common SE equipment and development of the SE devices as well as the previous SE team. We have already prepared a vertical-field superconducting magnet, a dilution refrigerator insert, a furnace with Nb heater and 2K cryostat as the BL-common SE equipment. In this fiscal year, a bottom-loading type He cryostat will be introduced. Moreover, we have just started developing high pressure system by collaborating with High Pressure Group in MLF, to comply with users' requests. We have also discussed the general purpose of apparatus for pulse magnet and for hydrogen environment. We plan to prepare more working area for the SE equipment, whose number gradually increases, and sample preparation and characterization rooms for users in the new building, which is under construction.
Kawamura, Seiko; Watanabe, Masao; Takahashi, Ryuta*; Munakata, Koji*; Takata, Shinichi; Sakaguchi, Yoshifumi*; Ishikado, Motoyuki*; Ouchi, Keiichi*; Arima, Hiroshi*; Hattori, Takanori; et al.
no journal, ,
At the Materials and Life Science Experimental Facility (MLF) in J-PARC, most of sample environment (SE) such as closed-cycle refrigerator (CCR) is prepared by the instruments individually as the standard SE equipment depending on the experiments carried out at the instrument. This system has advantages that the instrument group can directly contact the users and respond to their request and that the instrument can design its various components to adopt the instrument. On the other hand, several pieces of SE, which are not utilized so frequently but essential, are managed by the SE team. They are commonly used at several instruments in MLF. In these SEs, several cryostats, a high-temperature furnace and a superconducting magnet can be currently used for the inelastic and quasi-elastic neutron scattering experiments. Furthermore, high-pressure experiment using the Paris-Edinburgh press or clamped cell is also being prepared for these experiments.
electrons system URuSi under high fieldsSakai, Hironori; Higa, Nonoka; Hattori, Taisuke; Tokunaga, Yo; Haga, Yoshinori; Kambe, Shinsaku; Goto, Takayuki*; Hirata, Michihiro*; Awaji, Satoshi*; Sasaki, Takahiko*
no journal, ,
We have performed 
Si nuclear magnetic resonance (NMR) experiments using single crystal of strongly correlated 
electrons system URuSi under high external field of about 24 T. The temperature dependence of NMR shift in the paramagnetic state varies with external fields. The temperature and field dependences of NMR shifts resembles those of magnetic susceptibility.
