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.

Structure investigation on layered cathode materials of lithium-ion battery

Yonemura, Masao*; Kamiyama, Takashi*; Ishigaki, Toru; Mori, Kazuhiro*; Harjo, S.; Iwase, Kenji*; Takeuchi, Yoji*; Sasaki, Tsuyoshi*; Ukyo, Yoshio*

no journal, , 

The layered rock-salt structural materials, LiMO (M=Ni, Co, etc.) are promising candidates as cathodes in rechargeable lithium-ion batteries. These materials are defective in their electrochemical properties because their structures and thermal propertiesare unstable during the lithium (de)intercalation process. However, the substituted Li(Ni,Co,Al)O system shows the good electrochemical and thermal properties. The Mg doped system, Li(M,Mg)O, also shows good cycle stabilities. In this study, the effect of Mg doping into the Li(Ni,Co,Al,Mg)O system was studied with Mg compositions between 0 Mg 0.1. In this presentation, the detailed structure will be discussed.

Ibaraki materials design diffractometer for J-PARC

Ishigaki, Toru; Hoshikawa, Akinori; Yonemura, Masao*; Kamiyama, Takashi*; Harjo, S.; Aizawa, Kazuya; Sakuma, Takashi*; Tomota, Yo*; Morii, Yukio; Arai, Masatoshi; et al.

no journal, , 

Ibaraki prefecture, the local goverment of the area for J-PARC site, was decided to build a versatile neutron diffractometer (IBARAKI Materials Design Diffractometer) to promote a industrial application for neutron beam in J-PARC. This diffractometer is planned to be a high throughput diffractometer so that materials engineers and scientists can use it like the chemical analytical instruments in their materials development process. It covers in d range 0.18 d () 5 with = 0.16% at high resolution bank, and covers 5 d () 800 with gradually changing resolution at three detector bank (90 degree, low angle and small angle). Typical measuring time to obtain a "Rietveld-quality" data is several minutes with the sample size of laboratory X-ray diffractometer. To promote industrial application, a utilization system for this diffractometer is required. We will establish a support system for both academic and industrial users who are willing to use neutron but have not been familiar with neutron diffraction. The construction of this instrument was already begun and will be compleated in the beggining of 2008, as one of day-one instruments for J-PARC.

Present status for Ibaraki materials design diffractometer

Ishigaki, Toru; Hoshikawa, Akinori; Yonemura, Masao*; Kamiyama, Takashi*; Mori, Kazuhiro*; Mochiku, Takashi*; Aizawa, Kazuya; Arai, Masatoshi; Ebata, Kazuhiro*; Takano, Yoshiki*; et al.

no journal, , 

no abstracts in English

Software development for neutron experimental instruments at MLF, J-PARC

Nakatani, Takeshi; Inamura, Yasuhiro; Ito, Takayoshi; Kajimoto, Ryoichi; Aoyagi, Tetsuo; Ohara, Takashi; Otomo, Toshiya*; Yasu, Yoshiji*; Suzuki, Jiro*; Morishima, Takahiro*; et al.

no journal, , 

We have started the commissioning of the neutron scattering experiment instruments since May 2008 in MLF, J-PARC. Simultaneously, we have started the commissioning of the data acquisition and analysis software. Experimental users operate this software through the software framework which we have developed. The software framework was developed based on Python which is an object oriented script language. The system implemented with the software framework can seamlessly measure, analyze and visualize with some modules which are experimental control and data analysis. In this presentation, we report the process of the construction and the current status of the software.

Cross-sectional hydrogen content and mass density profiles of DLC film by neutron and X-ray reflectivity

Ozeki, Kazuhide*; Yonemura, Masao*; Masuzawa, Toru*; Saito, Hidetoshi*; Ogoe, Yasuharu*; Hirakuri, Kenji*; Takeda, Masayasu

no journal, , 

Hydrogen content in the DLC film is very important factor because it greatly influences on its mechanical properties and microstructure such as hardness, wear resistance, surface roughness, and sp3/sp2 ratio. In the present study, we prepared the DLC film using plasma CVD technique varying H/CH ratio from 0 to 9. Cross-sectional hydrogen content and mass density profiles of the films were defined by neutron and X-ray reflectivity measurements, and the results were compared with that from ERDA analysis. And O/C atomic ratio of the oxide layer of the film surface was also analyzed using XPS. From the neutron and X-ray reflectivity analysis, hydrogen content and mass density in the DLC film increased with film depth from the surface, and average hydrogen content showed more than 30 % in all films. By combining with XPS results, it is clarified that hydrogen content in the surface layer was lower than that in bulk layer.