Revealing the ion dynamics in LiGePS by quasi-elastic neutron scattering measurements

Hori, Satoshi*; Kanno, Ryoji*; Kwon, O.*; Kato, Yuki*; Yamada, Takeshi*; Matsuura, Masato*; Yonemura, Masao*; Kamiyama, Takashi*; Shibata, Kaoru; Kawakita, Yukinobu

Journal of Physical Chemistry C, 126(22), p.9518 - 9527, 2022/06

https://doi.org/10.1021/acs.jpcc.2c01748

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(8), p.083083_1 - 083083_9, 2020/08

https://doi.org/10.1088/1367-2630/aba98f

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 NaSnSeS 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.

Proceedings of the 21st Meeting of the International Collaboration on Advanced Neutron Sources (ICANS-XXI); Sep. 29 - Oct.3, 2014, Ibaraki Prefectural Center, Mito, Japan

Oku, Takayuki; Nakamura, Mitsutaka; Sakai, Kenji; Teshigawara, Makoto; Tatsumoto, Hideki*; Yonemura, Masao*; Suzuki, Junichi*; Arai, Masatoshi*

JAEA-Conf 2015-002, 660 Pages, 2016/02

JAEA-Conf-2015-002.pdf:168.34MB

The twenty first meeting of the International Collaboration on Advanced Neutron Source (ICANS-XXI) was held at Ibaraki Prefectural Culture Center in Mito from 29 September to 3 October 2014. It was hosted by Japan Atomic Energy Agency (JAEA), High Energy Accelerator Research Organization (KEK) and Comprehensive Research Organization for Science and Society (CROSS). In the meeting, new science and technology in the new era with the high power neuron sources were discussed in mostly "workshop style" sessions. In each session, various kinds of issues related to not only the hardware, but also the software and even radiation safety were discussed with the keyword of "INTERFACE". More than 200 Papers were presented in the meeting and 72 contributed papers are compiled in the proceedings.

Transformation strain and texture evolution during diffusional phase transformation of low alloy steels studied by neutron diffraction

Xu, P. G.; Tomota, Yo*; Vogel, S. C.*; Suzuki, Tetsuya*; Yonemura, Masao*; Kamiyama, Takashi*

Reviews on Advanced Materials Science, 33(5), p.389 - 395, 2013/08

http://www.ipme.ru/e-journals/RAMS/no_53313/02_533_xu.html

The Ibaraki prefecture materials design diffractometer for J-PARC; Designing neutron guide

Harjo, S.; Kamiyama, Takashi*; Torii, Shuki; Ishigaki, Toru; Yonemura, Masao*

Physica B; Condensed Matter, 385-386(Part 2), p.1025 - 1028, 2006/11

https://doi.org/10.1016/j.physb.2006.05.327

Ibaraki Prefecture Materials Design Diffractometer of J-PARC is a time-of-flight neutron powder diffractometer with the resolution as good as / = 0.16 % (almost constant value) for (L1 of 26.5 m). Since this diffractometer has many detectors covering wide 2 range, measurements with wide range, , i.e., PDF analysis and small angle scattering can also be performed. Designing of neutron guide is therefore very important to enhance the performances mentioned above without sacrificing beam intensity. Non-parallel guides including elliptical ones have been compared with a linear-straight guide using the McStas simulation. The elliptical guide having the exit focal points away behind the sample position is available to increase the neutron flux at the sample but give a slight lowering of the instrumental resolution. This elliptical guide gives also Garland peaks at short wavelengths that may give large ambiguities in powder diffraction measurements. Therefore, the linear-straight guide is considered as the best choice for this instrument to keep a good resolution and also a relatively high flux.

Phase diagram of solid solution of BiFeO-BaTiO3 system studied by neutron and X-ray powder diffraction

Kiyanagi, Ryoji; Yamazaki, Tadashi*; Sakamoto, Yuma*; Kimura, Hiroyuki*; Noda, Yukio*; Oyama, Kenji*; Torii, Shuki*; Yonemura, Masao*; Zhang, J.*; Kamiyama, Takashi

no journal, , 

Software for the engineering materials diffractometer (TAKUMI) at MLF, J-PARC

Ito, Takayoshi; Harjo, S.; Arima, Hiroshi; Abe, Jun; Moriai, Atsushi; Aizawa, Kazuya; Arai, Masatoshi; Nakatani, Takeshi; Inamura, Yasuhiro; Hosoya, Takaaki*; et al.

no journal, , 

no abstracts in English

In situ crystallographic observation of dynamic ferrite transformation evolution during hot deformation of low alloy steels

Xu, P. G.; Tomota, Yo*; Koo, M.*; Yonemura, Masao*; Suzuki, Tetsuya*; Paradowska, A.*; Zhang, S. Y.*; Adachi, Yoshitaka*

no journal, , 

Deformation induced ferrite transformation related to microstructure refinement has attracted wide attention. However, the in situ crystallographic evolution studies have not been carried out. In this paper, the deformation induced ferrite transformation at two different strain rates was carried out to compare that during isothermal holding without deformation and the effects of hot deformation and strain rate on the dynamic transformation evolution was investigated. The neutron diffraction experiments confirmed that the deformation induced ferrite transformations could appear not only in the austenite region, but also in the austenite-ferrite dual phase region. It was found that the low temperature deformation was more effective than the high temperature to promote the ferrite transformation until a critical strain, and then the accelerating effect was weakened due to the increment of austenite carbon concentration and the appearance of ferrite dynamic recrystallization.

Thermal expansion behavior of iron carbide FeC

Harjo, S.; Shiota, Yoshinori*; Yonemura, Masao*; Tomota, Yo*; Kamiyama, Takashi*; Umemoto, Minoru*

no journal, , 

Iron Carbide FeC (called "cementite") is an important phase for engineering steels. The amount and shape of cementite determine mechanical and thermal properties of the steels. Cementite is also suggested as the major phase in the inner core of the centre of the earth. However, since the cementite single-phase specimen was so difficult to prepare, its physical properties have not been examined well. Recently, the preparation of cementite bulky specimen has been performed by using plasma-sintering with mechanical milling. The lattice parameters of the prepared bulky pure cementite and Mn-alloyed cementite were measured at VEGA-KENS (Time-of-Flight neutron powder diffractometer) in a temperature range from room temperature to 673 K, to determine their thermal expansion coefficients. Results of the measurements will be presented.

Object oriented data analysis environment for neutron scattering

Suzuki, Jiro*; Kajimoto, Ryoichi; Ohara, Takashi; Yonemura, Masao*; Aoyagi, Tetsuo; Manabe, Atsushi*; Nakatani, Takeshi; Otomo, Toshiya*; Kawabata, Setsuya*

no journal, , 

Manyo-Lib is a framework of software designed for data analysis for neutron scattering experiment. It is one of the fundamental software used in J-PARC/MLF. Manyo-Lib consists of class libraries of C++ and Python interfaces that wrap the class libraries. The purpose of Manyo-lib is to offer operators for analysis, data containers, distributed computing environment, common data formats necessary to analyzing experiment data generated by various scattering equipments and various research regions. We are going to use NeXus as our common file format.