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Journal Articles

Strong lattice anharmonicity exhibited by the high-energy optical phonons in thermoelectric material

Wu, P.*; Fan, F.-R.*; Hagihara, Masato*; Kofu, Maiko; Peng, K.*; Ishikawa, Yoshihisa*; Lee, S.*; Honda, Takashi*; Yonemura, Masao*; Ikeda, Kazutaka*; et al.

New Journal of Physics (Internet), 22, p.083083_1 - 083083_9, 2020/08

 Times Cited Count:0

Thermoelectric material SnSe has aroused world-wide interests in the past years, and its inherent strong lattice anharmonicity is regarded as a crucial factor for its outstanding thermoelectric performance. However, the understanding of lattice anharmonicity in SnSe system remains inadequate, especially regarding how phonon dynamics are affected by this behavior. In this work, we present a comprehensive study of lattice dynamics on Na$$_{0.003}$$Sn$$_{0.997}$$Se$$_{0.9}$$S$$_{0.1}$$ by means of neutron total scattering, inelastic neutron scattering, Raman spectroscopy as well as frozen-phonon calculations. Lattice anharmonicity is evidenced by pair distribution function, inelastic neutron scattering and Raman measurements. By separating the effects of thermal expansion and multi-phonon scattering, we found that the latter is very significant in high-energy optical phonon modes. The strong temperature-dependence of these phonon modes indicate the anharmonicity in this system. Moreover, our data reveals that the linewidths of high-energy optical phonons become broadened with mild doping of sulfur. Our studies suggest that the thermoelectric performance of SnSe could be further enhanced by reducing the contributions of high-energy optical phonon modes to the lattice thermal conductivity via phonon engineering.

Journal Articles

Nature of structural instabilities in superconducting Sr$$_3$$Ir$$_4$$Sn$$_{13}$$

Kaneko, Koji; Cheung, Y. W.*; Hu, Y.*; Imai, Masaki*; Tanioku, Yasuaki*; Kanagawa, Hibiki*; Murakawa, Joichi*; Moriyama, Kodai*; Zhang, W.*; Lai, K. T.*; et al.

JPS Conference Proceedings (Internet), 30, p.011032_1 - 011032_6, 2020/03

Journal Articles

Lattice dynamics in FeSe via inelastic X-ray scattering and first-principles calculations

Murai, Naoki; Fukuda, Tatsuo; Nakajima, Masamichi*; Kawamura, Mitsuaki*; Ishikawa, Daisuke*; Tajima, Setsuko*; Baron, A. Q. R.*

Physical Review B, 101(3), p.035126_1 - 035126_6, 2020/01

 Times Cited Count:0 Percentile:100(Materials Science, Multidisciplinary)

We report an inelastic X-ray scattering investigation of phonons in FeSe superconductor. Comparing the experimental phonon dispersion with density functional theory (DFT) calculations in the non-magnetic state, we found a significant disagreement between them. A better overall agreement was obtained by allowing for spin-polarization in DFT calculations, despite the absence of magnetic order in FeSe. This calculation gives a realistic approximation, at DFT level, of the disordered paramagnetic state of FeSe, in which strong spin fluctuations are present.

Journal Articles

Evidence of a structural quantum critical point in (Ca$$_x$$Sr$$_{1-x}$$)$$_3$$Rh$$_4$$Sn$$_{13}$$ from a lattice dynamics study

Cheung, Y. W.*; Hu, Y. J.*; Imai, Masaki*; Tanioku, Yasuaki*; Kanagawa, Hibiki*; Murakawa, Joichi*; Moriyama, Kodai*; Zhang, W.*; Lai, K. T.*; Yoshimura, Kazuyoshi*; et al.

Physical Review B, 98(16), p.161103_1 - 161103_5, 2018/10

 Times Cited Count:4 Percentile:52.2(Materials Science, Multidisciplinary)

Journal Articles

Effect of rattling motion without cage structure on lattice thermal conductivity in LaOBiS$$_{2-x}$$Se$$_x$$

Lee, C. H.*; Nishida, Atsuhiro*; Hasegawa, Takumi*; Nishiate, Hirotaka*; Kunioka, Haruno*; Kawamura, Seiko; Nakamura, Mitsutaka; Nakajima, Kenji; Mizuguchi, Yoshikazu*

Applied Physics Letters, 112(2), p.023903_1 - 023903_4, 2018/01

 Times Cited Count:18 Percentile:11.01(Physics, Applied)

Low energy phonons in LaOBiS$$_{2-x}$$Se$$_x$$ are studied using inelastic neutron scattering. Dispersionless flat phonon branches that are mainly associated with a large vibration of Bi atoms are observed at a relatively low energy of $$E$$ = 6 - 6.7 meV. The phonon energy softens upon Se doping owing to its heavier atomic mass than S atom and the expansion of lattice constant. Simultaneously, the lattice thermal conductivity lowered upon Se doping as the same manner of the phonon softening. These suggest that despite the lack of an oversized cage in LaOBiS$$_{2-x}$$Se$$_x$$, rattling motions of Bi atoms can scatter phonon like rattling in cage compounds, contributing to enhance the thermoelectric property.

Journal Articles

Cross sections, stopping powers, and energy loss rates for rotational and phonon excitation processes in liquid water by electron impact

Kai, Takeshi; Yokoya, Akinari; Ukai, Masatoshi*; Watanabe, Ritsuko

Radiation Physics and Chemistry, 108, p.13 - 17, 2015/03

 Times Cited Count:9 Percentile:23.88(Chemistry, Physical)

Role of secondary electrons on DNA damage have not been understood sufficiently because there still exists a lack of cross section of rotational and phonon excitation in the liquid phase for precise simulation of the electron behavior. We calculated cross sections, stopping powers, and energy loss rates for the excitations in liquid water. The values for rotation are less by three orders of magnitude than those in the gas phase, while the values for phonon are close to those reported for amorphous ice. Thermalization process has so far been estimated from an assumption that the energy loss rates do not depend strongly on the energy below 1 eV. However, we found that the energy loss rates depend significantly on the energy. This fact indicates that the thermalization time will be longer than the previously estimated time, and we predict that thermalization process strongly involve in subsequent hydrated and chemical processes. The data set provide here is expected to useful to make the role of the secondary electrons on DNA damage much clear.

Journal Articles

Phonons in UCoGa$$_{5}$$

Metoki, Naoto; Kaneko, Koji; Raymond, S.*; Sanchez, J. P.*; Piekarz, P.*; Parlinski, K.*; Ole$'s$, A. M.*; Ikeda, Shugo; Matsuda, Tatsuma; Haga, Yoshinori; et al.

Physica B; Condensed Matter, 378-380, p.1003 - 1004, 2006/05

 Times Cited Count:12 Percentile:47.43(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Vibronic mechanism of high-${it Tc}$ superconductivity

Tachiki, Masashi*; Machida, Masahiko; Egami, Takeshi*

Physical Review B, 67(17), p.174506_1 - 174506_12, 2003/05

 Times Cited Count:45 Percentile:13.95(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Phonon measurement by using inelastic X-ray scattering

Fukuda, Tatsuo

Hamon, 13(1), p.43 - 46, 2003/01

no abstracts in English

Journal Articles

Inelastic nuclear resonant scattering of FeCl$$_{3}$$-graphite intercalation compounds

*; Mitsui, Takaya; Harami, Taikan; Yoda, Yoshitaka*; *

Japanese Journal of Applied Physics, 38(SUPPL.38-1), p.535 - 537, 1999/00

 Times Cited Count:0 Percentile:100(Physics, Applied)

no abstracts in English

Journal Articles

New aspects of the b$$^{ast}$$LA phonon of CuGeO$$_{3}$$

Nishi, Masakazu*; Kakurai, Kazuhisa*; Fujii, Yasuhiko*; Katano, Susumu; Akimitsu, Jun*; M.Yethiraj*; Fernandez-Baca, J. A.*

Journal of Physics and Chemistry of Solids, 60(8-9), p.1109 - 1111, 1999/00

 Times Cited Count:5 Percentile:65.08(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

[110]TA$$_{1}$$ phonon dispersion relation of the $$beta$$$$_{1}$$-phases in Ni-Co-Al alloys

*; *; *; Morii, Yukio

Journal of Physics and Chemistry of Solids, 60(8-9), p.1427 - 1429, 1999/00

 Times Cited Count:0 Percentile:100

no abstracts in English

Journal Articles

X-ray detection characteristics of Nb-based superconducting tunnel junctions

Katagiri, Masaki; Kishimoto, Maki; Ukibe, M.*; Nakamura, Tatsuya*; Kurakado, M.*; Maehata, Keisuke*; *; Nakazawa, Masaharu*

Japanese Journal of Applied Physics, 37(SUPPL.37-2), p.13 - 18, 1998/00

 Times Cited Count:6 Percentile:70.26(Physics, Applied)

no abstracts in English

Journal Articles

Soft modes and phonon interactions in Sn$$_{2}$$P$$_{2}$$Se$$_{6}$$ studied by means of neutron scattering

S.W.H.Eijt*; R.Currat*; J.E.Lorenzo*; P.Gregoire*; Katano, Susumu; T.Janssen*; B.Hennion*; Y.Vysochanskii*

Journal of Physics; Condensed Matter, 10(22), p.4811 - 4844, 1998/00

 Times Cited Count:49 Percentile:10.99(Physics, Condensed Matter)

no abstracts in English

Journal Articles

Phonon measurement of RbCl at 4.9 kbar

Ishii, Yoshinobu; *; Onodera, Akifumi*; *; Morii, Yukio

Physica B; Condensed Matter, 241-243, p.409 - 411, 1998/00

 Times Cited Count:3 Percentile:71.79(Physics, Condensed Matter)

no abstracts in English

JAEA Reports

Thermal conductivity of neutron-irradiated uni-directional carbon fiber reinforced carbon material

Saito, Tamotsu; K.Deng*; Nakano, Junichi; Yamada, Reiji

JAERI-Research 97-001, 18 Pages, 1997/01

JAERI-Research-97-001.pdf:0.85MB

no abstracts in English

Journal Articles

X-ray signal production processes in Nb-based superconducting tunnel junctions

Katagiri, Masaki; Kishimoto, Maki; H.Kraus*; Ukibe, M.*; Kurakado, M.*; Nakazawa, Masaharu*; Maehata, Keisuke*; *; Nakamura, Tatsuya*

Proc. of 7th Int. Workshop on Low Temperature Detectors (LTD-7), p.39 - 44, 1997/00

no abstracts in English

Journal Articles

Neutron scattering studies of the effects of uniaxial stress and ageing on the $$beta$$$$_{1}$$-Cu-Al-Zn alloy

*; *; Morii, Yukio

Journal of the Physical Society of Japan, 65(3), p.778 - 781, 1996/03

 Times Cited Count:0 Percentile:100(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Two-phonon $$gamma$$-vibrational state in $$^{168}$$Er

Oshima, Masumi; *; ; ; Shinohara, Nobuo; *; Kusakari, Hideshige*; *; Sugawara, Masahiko*; *

Physical Review C, 52(6), p.3492 - 3495, 1995/12

 Times Cited Count:27 Percentile:19(Physics, Nuclear)

no abstracts in English

Journal Articles

Dynamical structure analysis applied to Si and Ge

J.Kulda*; Ishii, Yoshinobu; Katano, Susumu

Physica B; Condensed Matter, 213&214, p.427 - 429, 1995/00

 Times Cited Count:2 Percentile:80.78

no abstracts in English

36 (Records 1-20 displayed on this page)