Hydrogen vibration excitations of ZrH and TiH up to 21 GPa by incoherent inelastic neutron scattering

Hattori, Takanori; Nakamura, Mitsutaka; Iida, Kazuki*; Machida, Akihiko*; Sano, Asami; Machida, Shinichi*; Arima, Hiroshi*; Oshita, Hidetoshi*; Honda, Takashi*; Ikeda, Kazutaka*; et al.

Physical Review B, 106(13), p.134309_1 - 134309_9, 2022/10

https://doi.org/10.1103/PhysRevB.106.134309

Hydrogen vibration excitations of fluorite-type ZrH and TiH were investigated up to 21 GPa and 4 GPa, respectively, by incoherent inelastic neutron scattering experiments. The first excitation energies increased with pressure, as described by the equations (meV) = 141.4(2) + 1.02(2)(GPa) and (meV) = 149.4(1) + 1.21(8)(GPa) for ZrH and TiH, respectively. Coupling with pressure dependence of lattice parameters, the relations between metal-hydrogen distance () and are found to be well described by the equations (meV) = 1.62(9) 10 ((meV) = 1.47(21) 10 (AA), respectively. The slopes of these curves are much steep compared to the previously reported trend in various fluorite-type metal hydrides at ambient pressure. The hydrogen wave function spreading showed that the local potential field for a hydrogen atom shrinks more intensively than the tetrahedral site. These behavior is likely caused by the rigid metal ion core and the resulting confinement of the hydrogen atom in the narrower potential field at high pressures.

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

https://doi.org/10.3390/qubs1030009

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Local structural analysis by using atomic pair distribution function on mixed valence compound LiMnO

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro; Hoshikawa, Akinori*; Ishigaki, Toru*

JPS Conference Proceedings (Internet), 3, p.013012_1 - 013012_6, 2014/06

https://doi.org/10.7566/JPSCP.3.013012

Local lattice distortion caused by short range charge ordering in LiMnO

Kodama, Katsuaki; Igawa, Naoki; Shamoto, Shinichi; Ikeda, Kazutaka*; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Otomo, Toshiya*; Suzuya, Kentaro

Journal of the Physical Society of Japan, 82(9), p.094601_1 - 094601_6, 2013/09

https://doi.org/10.7566/JPSJ.82.094601

Visibility estimation for neutron resonance absorption radiography using a pulsed neutron source

Kai, Tetsuya; Maekawa, Fujio; Oshita, Hidetoshi*; Sato, Hirotaka; Shinohara, Takenao; Oi, Motoki; Harada, Masahide; Uno, Shoji*; Otomo, Toshiya*; Kamiyama, Takashi*; et al.

Physics Procedia, 43, p.111 - 120, 2013/00

https://doi.org/10.1016/j.phpro.2013.03.014

A neutron imaging instrument is in construction at the pulsed neutron source of J-PARC. Some demonstration experiments in NOBORU/J-PARC have carried. To explore widespread applications of the newly built instruments it is indispensable to indicate the range of coverage of this technique. In the presentation, the authors describe the results of some of demonstration measurements, and then compare all elements with the values obtained by multiplying peak cross section and peak widths of neutron resonances in evaluated nuclear data libraries. This value is expected to be a good measure to exhibit visibility of each element in this technique.

Present status of NOVA; J-PARC neutron total diffractometer

Suzuya, Kentaro; Takata, Shinichi; Shamoto, Shinichi; Otomo, Toshiya*; Misawa, Masakatsu*; Kaneko, Naokatsu*; Oshita, Hidetoshi*

no journal, , 

Design concept of high-intensity total diffractometer of J-PARC is wide-Q range measurements with the highest neutron intensity by the pulsed neutron source. The resolution of the diffractometer is reasonable for crystalline materials and the diffractometer will cover very wide research fields in term nano structure and/or non-crystalline materials. Hydrogen absorption mechanism will be intensively investigated with the diffractometer.

Hydrogen structure study by high pressure neutron diffraction using total scattering spectrometer NOVA

Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Machida, Akihiko; Katayama, Yoshinori; Arima, Hiroshi; Komatsu, Kazuki*; Oshita, Hidetoshi*; Otomo, Toshiya*

no journal, , 

no abstracts in English

Hydrogen structrue study by high pressure neutron diffraction using NOVA

Honda, Mitsunori; Hattori, Takanori; Machida, Akihiko; Arima, Hiroshi; Sano, Asami; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Oshita, Hidetoshi*; Otomo, Toshiya*

no journal, , 

no abstracts in English

Neutron diffraction study of pressure-induced phase separation of LaD

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.

Ionic conduction path in AgGeSe superionic glass

Kawakita, Yukinobu; Otomo, Toshiya*; Ueno, Hiroki; Tsubota, Masami*; Kumara, L. S. R.*; Oshita, Hidetoshi*; Suzuya, Kentaro

no journal, , 

Ag(GeSe) ternary alloy exhibits an extensive compositional range of bulk glass forming and a rapid enhancement in ionic conductivity from 10 to 10 S/cm of these glasses at Ag concentration of x=0.3 with increasing Ag content. Structural models of this material have already been proposed by reverse Monte Carlo simulation based on experimental structural data of neutron and X-ray diffractions and X-ray absorption fine structure. However, there observed micro-phase separation tendency in these glasses. This tendency might relate to formation of ionic conduction path in supercooled liquid on quenching process. The proposed models will be examined by structure factors over a wide Q range including relatively low momentum-transfer region which have been newly obtained by the total neutron scattering instrument installed at BL21 in MLF, J-PARC. This work was supported by NEDO under "Advanced Fundamental Research Project on Hydrogen Storage Materials".