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.

Direct observation of strain in InAs quantum dots and cap layer during molecular beam epitaxial growth using X-ray diffraction

Shimomura, Kenichi*; Suzuki, Hidetoshi*; Sasaki, Takuo; Takahashi, Masamitsu; Oshita, Yoshio*; Kamiya, Itaru*

Journal of Applied Physics, 118(18), p.185303_1 - 185303_7, 2015/11

https://doi.org/10.1063/1.4935456

three-dimensional X-ray reciprocal-space mapping of InGaAs multilayer structures grown on GaAs(001) by MBE

Sasaki, Takuo; Takahashi, Masamitsu; Suzuki, Hidetoshi*; Oshita, Yoshio*; Yamaguchi, Masafumi*

Journal of Crystal Growth, 425, p.13 - 15, 2015/09

https://doi.org/10.1016/j.jcrysgro.2015.03.044

2D neutron diffraction imaging on an ammonite

Shamoto, Shinichi; Kodama, Katsuaki; Imaki, Tadashi*; Nakatani, Takeshi; Oshita, Hidetoshi*; Kaneko, Naokatsu*; Masuko, Kenji*; Sakamoto, Kensaku; Yamaguchi, Kenji; Suzuya, Kentaro; et al.

JPS Conference Proceedings (Internet), 1, p.014011_1 - 014011_5, 2014/03

https://doi.org/10.7566/JPSCP.1.014011

2D neutron diffraction imaging of an ammonite fossil was carried out at high-intensity total diffractometer NOVA in J-PARC. Observed diffraction profiles consist of calcite, siderite and amorphous structures.

In situ three-dimensional X-ray reciprocal-space mapping of GaAs epitaxial films on Si(001)

Takahashi, Masamitsu; Nakata, Yuka*; Suzuki, Hidetoshi*; Ikeda, Kazuma*; Kozu, Miwa; Hu, W.; Oshita, Yoshio*

Journal of Crystal Growth, 378, p.34 - 36, 2013/09

https://doi.org/10.1016/j.jcrysgro.2012.12.119

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

https://doi.org/10.5611/hamon.23.1_131

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 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 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.

Formation of NaCl-type monodeuteride LaD by the disproportionation reaction of LaD

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

https://doi.org/10.1103/PhysRevLett.108.205501

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.

Real-time structural analysis of compositionally graded InGaAs/GaAs(001) layers

Sasaki, Takuo*; Suzuki, Hidetoshi*; Inagaki, Makoto*; Ikeda, Kazuma*; Shimomura, Kenichi*; Takahashi, Masamitsu; Kozu, Miwa*; Hu, W.; Kamiya, Itaru*; Oshita, Yoshio*; et al.

IEEE Journal of Photovoltaics, 2(1), p.35 - 40, 2012/01

https://doi.org/10.1109/JPHOTOV.2011.2174198

Growth temperature dependence of strain relaxation during InGaAs/GaAs(0 0 1) heteroepitaxy

Sasaki, Takuo*; Suzuki, Hidetoshi*; Sai, Akihisa*; Takahashi, Masamitsu; Fujikawa, Seiji; Kamiya, Itaru*; Oshita, Yoshio*; Yamaguchi, Masafumi*

Journal of Crystal Growth, 323(1), p.13 - 16, 2011/05

https://doi.org/10.1016/j.jcrysgro.2010.10.005

Growth temperature dependence of strain relaxation during InGaAs/GaAs(001) molecular beam epitaxy was studied by in situ X-ray reciprocal space mapping. Evolution of the residual strain and crystal quality for the InGaAs film was obtained as a function of film thickness at growth temperatures of 420, 445 and 477 C. In the early stages of strain relaxation, it was found that evolution of the residual strain and crystal quality was dependent on the growth temperature. In order to discuss this observation quantitatively, the strain relaxation model was proposed based on the Dodson-Tsao kinetic model, and its validity was demonstrated by good agreement with the experimental residual strain. Additionally, rate coefficients reflecting dislocation motions during strain relaxation were obtained as a function of growth temperature and strain relaxation was discussed in terms of the thermally active dislocation motion.