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Journal Articles

Dynamics of water in a catalyst layer of a fuel cell by quasielastic neutron scattering

Ito, Kanae; Yamada, Takeshi*; Shinohara, Akihiro*; Takata, Shinichi; Kawakita, Yukinobu

Journal of Physical Chemistry C, 125(39), p.21645 - 21652, 2021/10

 Times Cited Count:0

Journal Articles

Microscopic dynamics of lithium diffusion in single crystal of the solid-state electrolyte La$$_{2/3-x}$$Li$$_{3x}$$TiO$$_{3}$$ (x = 0.13) studied by quasielastic neutron scattering

Matsuura, Masato*; Fujiwara, Yasuyuki*; Moriwake, Hiroki*; Ohara, Koji*; Kawakita, Yukinobu

Physical Review B, 104(9), p.094305_1 - 094305_7, 2021/09

 Times Cited Count:0

Journal Articles

Conformational dynamics of a multidomain protein by neutron scattering and computational analysis

Nakagawa, Hiroshi; Saio, Tomohide*; Nagao, Michihiro*; Inoue, Rintaro*; Sugiyama, Masaaki*; Ajito, Satoshi; Tominaga, Taiki*; Kawakita, Yukinobu

Biophysical Journal, 120(16), p.3341 - 3354, 2021/08

 Times Cited Count:0 Percentile:0.01(Biophysics)

A multi-domain protein can have various conformations in solution. Interactions with other molecules result in the stabilization of one of the conformations and change in the domain dynamics. SAXS, a well-established experimental technique, can be employed to elucidate the conformation of a multi-domain protein in solution. NSE spectroscopy is a promising technique for recording the domain dynamics in nanosecond and nanometer scale. Despite the great efforts, there are still under development. Thus, we quantitatively removed the contribution of diffusion dynamics and hydrodynamic interactions from the NSE data via incoherent scattering, revealing the differences in the domain dynamics of the three functional states of a multi-domain protein, MurD. The differences among the three states can be explained by two domain modes.

Journal Articles

Mode distribution analysis for superionic melt of CuI by coherent quasielastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Tahara, Shuta*; Nakamura, Mitsutaka; Inamura, Yasuhiro; Maruyama, Kenji*; Yamauchi, Yasuhiro*; Kawamura, Seiko; Nakajima, Kenji

JPS Conference Proceedings (Internet), 33, p.011071_1 - 011071_6, 2021/03

CuI is a well-known superionic conductor in a high temperature solid phase where the mobile cations migrate between interstitial sites in the f.c.c. sublattice formed by iodine ions. Even in the molten state, it shows several features suggesting collective or cooperative ionic motion. MD results show that Cu diffuses much faster than I. The Cu-Cu partial structure factor have a FSDP which indicates a medium-range ordering of Cu ions. Moreover the Cu-Cu partial pair distribution deeply penetrates into the nearest neighboring Cu-I shell. To reveal origin such anomalous behaviors of molten CuI, we performed quaiselastic neutron scattering (QENS) by the disk-chopper spectrometer AMATERAS at MLF, J-PARC. To interpret the total dynamic structure factor obtained from coherent QENS, the mode distribution analysis was applied. It is found that the motion of iodine is a kind of fluctuating within an almost local area while Cu ions diffuse much faster than iodine ions.

Journal Articles

Corrosion of aluminum-based containers for neutron studies with aqueous samples under low temperatures

Tominaga, Taiki*; Sahara, Masae*; Kawakita, Yukinobu; Nakagawa, Hiroshi; Shimamoto, Naonobu*

JPS Conference Proceedings (Internet), 33, p.011094_1 - 011094_5, 2021/03

In quasielastic neutron scattering studies, aluminum or aluminum alloys are frequently employed as sample cells. With the increasing incident-neutron flux, the research area currently continues to expand; thus, obtaining data has become quicker than ever for dilute conditions. One such area is the water-containing systems. In this study, we investigated the effect of temperature on Al and found that even in a low temperature atmosphere, Al corrosion can occur. This was attributed to the different thermal expansion coefficients of Al as a base substrate and Al oxide as a passivating film.

Journal Articles

Position dependency of the scattered intensity in the time-of-flight backscattering spectrometer DNA

Matsuura, Masato*; Yamada, Takeshi*; Tominaga, Taiki*; Kobayashi, Makoto*; Nakagawa, Hiroshi; Kawakita, Yukinobu

JPS Conference Proceedings (Internet), 33, p.011068_1 - 011068_6, 2021/03

The position dependence of the scattered intensity in the time-of-flight backscattering spectrometer DNA was investigated. A periodic structure for both vertical (pixel) and horizontal (PSD) directions was observed. The solar slit and over-bending of an analyzer crystal is discussed as a possible origin of the modulation in the intensity. We have developed software program for the systematic correction of the position-dependent intensity and offset energy for the elastic peak. This corrects the deviation from the true scattering intensity and improve the quality of the data, which includes the energy resolution.

Journal Articles

Position-encoded automatic cell elevator for BL02, J-PARC MLF

Tominaga, Taiki*; Kobayashi, Makoto*; Yamada, Takeshi*; Matsuura, Masato*; Kawakita, Yukinobu; Kasai, Satoshi*

JPS Conference Proceedings (Internet), 33, p.011095_1 - 011095_5, 2021/03

A vertical movement type of sample changer for the neutron spectrometer BL02, J-PARC MLF was developed for our top-loading type cryostat. The sample changer, termed as "PEACE", can control reproducibility of the irradiated position using guides made of polyether ether ketone. The variation between the background scattering profiles of three sample positions was found to be less than plus minus 1.6%. This result is reasonable, considering the deviation of sample position of less than plus minus 0.3 mm from the vertical axis.

Journal Articles

Quartz cell for a backscattering spectrometer

Tominaga, Taiki*; Kawakita, Yukinobu; Nakagawa, Hiroshi; Yamada, Takeshi*; Shibata, Kaoru

JPS Conference Proceedings (Internet), 33, p.011086_1 - 011086_5, 2021/03

We developed a quartz double cylindrical sample cell optimized for a backscattering neutron spectrometer, especially for BL02 (DNA), MLF in J-PARC. A quartz glass tube, with one end closed, is shaved to obtain a wall thickness of 0.55 mm. The inner tube is properly centered using a protrusion into the outer tube such that the interstice between the outer and inner tubes keeps constant. This quartz cell can be used for samples that should not be in contact with the aluminum surface. We verified cell's background effect between the quartz cell and Al cell by QENS measurements using D$$_{2}$$O buffer. The elastic intensity profiles of the buffer in a low Q region were identical between both quartz cell and Al cell (A1070). In a high Q region, however, the profiles were different caused by the first sharp diffraction peak of quartz glass. For this region the data should be analyzed by consideration of absorption correction and diffraction in individual thickness of quartz cell.

Journal Articles

Local- and intermediate-range order in room temperature superionic conducting Ag-GeSe$$_{3}$$ glasses

Hosokawa, Shinya*; Kawakita, Yukinobu; Stellhorn, J. R.*; Pusztai, L.*; Blanc, N.*; Boudet, N.*; Ikeda, Kazutaka*; Otomo, Toshiya*

JPS Conference Proceedings (Internet), 33, p.011070_1 - 011070_7, 2021/03

Local- and intermediate-range atomic order in Ag ion conducting glasses Ag$$_{x}$$(GeSe$$_{3}$$)$$_{1-x}$$ with x = 0.15, 0.28, 0.33, and 0.50 were investigated by using a combination of AXS, XRD, ND, and RMC modeling. By adding the ND pdf to AXS and XRD results, reasonable partial structure factors and partial pdf were obtained by the RMC procedure. In contrast to the previous AXS and RMC study, a large number of Ag-Ge and Ge-Ge correlations are observed in the first coordination shell region, which is consistent with an ${it ab initio}$ MD simulation. The coordination numbers around the Ge and Se mostly follow the 8-$$N$$ rule over all Ag concentrations if Ag is not taken into account. With increasing the Ag concentration, the partial coordination numbers with Ge and Se atoms around Ag remarkably increases, while the Ag-Ag coordination number increases only slightly, indicating that the Ag conducting path is formed through the second neighboring Ag-Ag correlations.

Journal Articles

Relevance of hydrogen bonded associates to the transport properties and nanoscale dynamics of liquid and supercooled 2-propanol

Zhai, Y.*; Luo, P.*; Nagao, Michihiro*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kawakita, Yukinobu; Kienzle, P. A.*; Z, Y.*; Faraone, A.*

Physical Chemistry Chemical Physics, 23(12), p.7220 - 7232, 2021/03

 Times Cited Count:0 Percentile:0.01(Chemistry, Physical)

Journal Articles

Detailed investigations on short- and intermediate-range structures of Ge-Se glasses near the stiffness transition composition

Hosokawa, Shinya*; Kawakita, Yukinobu; Pusztai, L.*; Ikeda, Kazutaka*; Otomo, Toshiya*

Journal of the Physical Society of Japan, 90(2), p.024601_1 - 024601_12, 2021/02

 Times Cited Count:0 Percentile:0(Physics, Multidisciplinary)

Journal Articles

Magnetism induced by interlayer electrons in the quasi-two-dimensional electride Y$$_{2}$$C; Inelastic neutron scattering study

Tamatsukuri, Hiromu; Murakami, Yoichi*; Kuramoto, Yoshio*; Sagayama, Hajime*; Matsuura, Masato*; Kawakita, Yukinobu; Matsuishi, Satoru*; Washio, Yasuhito*; Inoshita, Takeshi*; Hamada, Noriaki*; et al.

Physical Review B, 102(22), p.224406_1 - 224406_5, 2020/12

 Times Cited Count:3 Percentile:58.93(Materials Science, Multidisciplinary)

Journal Articles

Dynamics of proteins with different molecular structures under solution condition

Inoue, Rintaro*; Oda, Takashi*; Nakagawa, Hiroshi; Tominaga, Taiki*; Saio, Tomohide*; Kawakita, Yukinobu; Shimizu, Masahiro*; Okuda, Aya*; Morishima, Ken*; Sato, Nobuhiro*; et al.

Scientific Reports (Internet), 10, p.21678_1 - 21678_10, 2020/12

 Times Cited Count:0 Percentile:0(Multidisciplinary Sciences)

Incoherent quasielastic neutron scattering (iQENS) is a fascinating technique for investigating the internal dynamics of protein. However, both low flux of neutron beam and absence of analytical procedure for extracting the internal dynamics from iQENS profile have been obstacles for studying it under physiological condition (in solution). Thanks to the recent development of neutron source, spectrometer and computational technique, they enable us to decouple internal dynamics, translational and rotational diffusions from the iQENS profile. The internal dynamics of two proteins: globular domain protein (GDP) and intrinsically disordered protein (IDP) in solution were studied. It was found that the average relaxation rate of IDP was larger than that of GDP. Through the detailed analyses on their internal dynamics, it was revealed that the fraction of mobile H atoms in IDP was much higher than that in GDP. Interestingly, the fraction of mobile H atoms was closely related to the fraction of H atoms on highly solvent exposed surfaces. The iQENS study presented that the internal dynamics were governed by the highly solvent exposed amino acid residues depending upon protein molecular architectures.

Journal Articles

Applicability and limitations of $$G(r,E)$$ analysis transformed from the inelastic neutron scattering data

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 567, p.61 - 64, 2019/08


 Times Cited Count:0 Percentile:0(Physics, Condensed Matter)

Recently, we reported the phonon dynamical study of a polycrystalline NaI by using the dynamical structure factor in real-space $$G(r,E)$$ transformed from the inelastic neutron scattering (INS) data. Our study has shown that the INS experiments under the conventional condition Q$$_{max}$$ $$sim$$ 5$AA$^{-1}$$ can provide us a meaningful information on the phonon dynamics at around the first nearest neighbor distance on accepting the worse real-space resolution. These results suggest the possibility that a large amount of $$S(Q,E)$$ data which were previously obtained can be effectively reused. In this study, we will examine both the applicability and limitations of $$G(r,E)$$ analysis for various types of materials whose INS data were obtained at the Fermi chopper spectrometer 4SEASONS in J-PARC.

Journal Articles

Real time and real space analysis for coherent QENS and its application to liquid bismuth

Kikuchi, Tatsuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 567, p.51 - 54, 2019/08

 Times Cited Count:0 Percentile:0(Physics, Condensed Matter)

Journal Articles

Status of neutron spectrometers at J-PARC

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Nakamura, Mitsutaka; Kawakita, Yukinobu; Matsuura, Masato*; Endo, Hitoshi*; Seto, Hideki*; Ito, Shinichi*; Nakajima, Kenji; Kawamura, Seiko

Physica B; Condensed Matter, 562, p.148 - 154, 2019/06


 Times Cited Count:5 Percentile:48.71(Physics, Condensed Matter)

Journal Articles

Anomalous structure of liquid Bi studied by coherent QENS and time-space correlation analysis

Kawakita, Yukinobu; Kikuchi, Tatsuya*

Hamon, 29(2), p.91 - 94, 2019/05

Bismuth (Bi) has a double-layered structure based on Peierls distortion in crystalline phase. Complicated static structure in liquid phase which cannot be interpreted by a simple packing model has been conjectured that Peierls distortion may remain even in liquid phase. We measured quasi-elastic neutron scattering (QENS) of liquid Bi by using AMATERAS installed at BL14 beamport of Materials and Life Science Experimental Facility (MLF) in J-PARC and analyzed coherent QENS spectra. A time-space correlation function revealed that the nearest neighboring shell followed by a shoulder-like structure at longer side consists of four contributions of short and long correlations with relatively long relaxation time of a few tens pico second and medium-ranged and the longest correlations with a short relaxation time of sub-pico second, which is a direct observation of the existing layered structure in liquid Bi. In this article, we report the above scientific results and the method to analyze coherent QENS by the time-space correlation function.

Journal Articles

Colossal barocaloric effects in plastic crystals

Li, B.*; Kawakita, Yukinobu; Kawamura, Seiko; Sugahara, Takeshi*; Wang, H.*; Wang, J.*; Chen, Y.*; Kawaguchi, Saori*; Kawaguchi, Shogo*; Ohara, Koji*; et al.

Nature, 567(7749), p.506 - 510, 2019/03

 Times Cited Count:85 Percentile:99.22(Multidisciplinary Sciences)

Refrigeration is of vital importance for modern society for example, for food storage and air conditioning- and 25 to 30% of the world's electricity is consumed for refrigeration. Current refrigeration technology mostly involves the conventional vapour compression cycle, but the materials used in this technology are of growing environmental concern because of their large global warming potential. As a promising alternative, refrigeration technologies based on solid-state caloric effects have been attracting attention in recent decades. However, their application is restricted by the limited performance of current caloric materials, owing to small isothermal entropy changes and large driving magnetic fields. Here we report colossal barocaloric effects (CBCEs) (barocaloric effects are cooling effects of pressure-induced phase transitions) in a class of disordered solids called plastic crystals. The obtained entropy changes in a representative plastic crystal, neopentylglycol, are about 389 joules per kilogram per kelvin near room temperature. Pressure-dependent neutron scattering measurements reveal that CBCEs in plastic crystals can be attributed to the combination of extensive molecular orientational disorder, giant compressibility and highly anharmonic lattice dynamics of these materials. Our study establishes the microscopic mechanism of CBCEs in plastic crystals and paves the way to next-generation solid-state refrigeration technologies.

Journal Articles

Phonon dynamics of NaI investigated by G($$r,E$$) analysis

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 551, p.351 - 354, 2018/12


 Times Cited Count:2 Percentile:16.65(Physics, Condensed Matter)

The dynamic structure function in real space G($$r,E$$) is deduced from the dynamical structure factor S($$Q,E$$) which can be obtained from inelastic neutron scattering measurement. In this study, we applied the G($$r,E$$) analysis to NaI which is a typical alkali halide crystal. The optic and acoustic phonons of NaI are widely separated in energy because the difference in mass between the constituent atoms is large. These characteristic properties certainly help us to evaluate the G($$r,E$$) features associated with the phonon modes. We measured the S($$Q,E$$) for NaI powder using the Fermi chopper spectrometer 4SEASONS at J-PARC, and converted S($$Q,E$$) into G($$r,E$$) by newly developed software which utilizes the maximum entropy method. Our analysis clearly demonstrated the G($$r,E$$) of TO mode oscillates out of phase with that of LA mode, which is physically reasonable. Further analyses will be given in the presentation.

Journal Articles

Anomaly of structural relaxation in complex liquid metal of bismuth; Dynamic correlation function of coherent quasi-elastic neutron scattering

Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.

Physica B; Condensed Matter, 551, p.291 - 296, 2018/12

 Times Cited Count:8 Percentile:49.07(Physics, Condensed Matter)

There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.

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