１１月２８日、赤井教授（産業ナノマテリアル研究所)及び、細川特任教授（産業ナノマテリアル研究所）が世話人となり、第１０８回IROASTセミナーが開催されました。会場はもとよりオンラインにより学内と海外から、教員及び学生が参加しました。

グルノーブルアルプ大学/SiMAP所属マーク・ドゥ・ボアシュー博士が、構造的に複雑な物質における熱伝導性と格子ダイナミクスに関する研究成果と経験について、幅広い視野から講演を行いました。

セミナーに先立ち、マーク・ドゥ・ボアシュー博士と受入教員の細川特任教授が高島研究機構長を訪問し、簡単な意見交換を行いました。

On November 28, 2023, the 108th IROAST Seminar, organized by Prof. Ichiro AKAI (IINa) and Prof. Shinya HOSOKAWA (IINa) was held. Faculty members and students from both on-campus and overseas participated in the seminar, not only at the venue but also online.

Dr. Marc De Boissieu (SiMAP-Grenoble Alpes University, France) gave a broad view of his research findings and experiences on thermal conductivity and lattice dynamics in structurally complex materials.

Prior to the seminar, Dr. Marc De BOISSUIEU and Special Prof. HOSOKAWA, his host faculty member, visited Director TAKASHIMA and had a brief discussion.

*IINa:  Institute of Industrial Nanomaterials, Kumamoto University

■Organizer世話人

細川　伸也　特任教授　（産業ナノマテリアル研究所）
Special Prof. Shinya HOSOKAWA, Institute of Industrial Nanomaterials

■Speaker｜講演者

グルノーブルアルプ大学/SiMAP　マーク・ドゥ・ボアシュー博士
Dr. Marc De Boissieu (SiMAP-Grenoble Alpes University, France)

■At Venue|会場の様子

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■Meeting with Director TAKASHIMA｜高島研究機構長との面談の様子

At Director's office on December 27, 2023

From left, Dr. De Boissieu, Dr. Hosokawa, and Dr. Takashima

The 108th IROAST Seminar 第108回IROASTセミナー開催のお知らせ

国際先端科学技術研究機構（IROAST）は、グルノーブルアルプ大学（SiMAP）所属マーク・ドゥ・ボアシュー博士による、第108回IROASTセミナーを下記のとおり開催いたします。
興味のある方はどなたでもご参加いただけます。多くの皆さまのご参加をお待ちしております。
本セミナーは英語にて行います。事前登録は不要です。

1．日　時：令和5年11月28日（火）16:25～17:55

2．会　場：黒髪南E1 69番 (理学部1・2号館)　C122講義室
                       ※会場講演に加え、オンラインでも開催
　　　　　　（Zoomの情報は本サイト下部にある問い合わせまでご連絡ください。）　 

3．講演者 (Speaker)：Director,  マーク・ドゥ・ボアシュー博士
                                          (グルノーブル・アルプ大学/SiMAP, フランス)                                                               

4．演題 (Title)：  “Thermal conductivity and lattice dynamics in structurally complex materials”

5.   概要（Abstract）：

Understanding the lattice thermal conductivity of materials is of key importance in various fields of material science: for thermoelectric, thermal barriers, thermal transport…. Whereas it is well understood for simple atomic structures, it remains a challenging question for structurally complex materials.

In this lecture I will focus on those materials displaying a ‘glass like thermal conductivity’ [1], with a relatively small value of the lattice thermal conductivity at ambient temperature and an almost independent temperature dependence in the range 20 to 300 K. This is the case for many different systems such as amorphous materials, disordered periodic crystals [1], clathrates [2], but also aperiodic crystals [3] such as the icosahedral quasicrystal i-AlPdMn [4], and the Rb2ZnCl4 phase that displays an incommensurately modulated phase between 190 and 300 K [5].

All these structures can be characterized by what can be named ‘structural complexity’.  I will first introduce the notion of structural complexity which can be characterized by two main parameters: (i) the long range order and the number of atoms in the unit cell (which goes to infinity for aperiodic crystals); (ii) the disorder that breaks the long range order and may occur as chemical site disorder or lattice displacement, with in the extreme case of amorphous systems the absence of long range order.

I will then review some of the recent results obtained in different materials by combining state of the art inelastic x-ray and neutron scattering with atomic scale simulation. We will show that phonons do not behave at all as in a glass: there is a restricted energy range for which acoustic phonons do propagate, with a rather large mean free path. A simple phonon lattice gaz model as proposed for clathrates [2] can be generalized to interpret the data and resolve the apparent paradoxal findings. The importance of including properly the disorder in large atomic scale simulation will also be discussed [6].

[1]          D. G. Cahill, S. K. Watson, and R. O. Pohl, Phys. Rev. B 46, 6131 (1992).
[2]          P.-F. Lory et al., Nat. Com. 8, 491 (2017).
[3]          T. Janssen, G. Chapuis, and M. de Boissieu, Aperiodic Crystals. From modulated phases to quasicrystals (second edition) (Oxford University Press, Oxford, 2018), Vol. 20, IUCr Monographs on Crystallography.
[4]          M. A. Chernikov, A. Bianchi, and H. R. Ott, Phys. Rev. B 51, 153 (1995).
[5]          D.-M. Zhu and A. C. Anderson, J. Low Temp. Phys. 94, 117 (1994).
[6]          P. F. Lory et al., Phys. Rev. B 102, 024303, 024303 (2020).

6．世話人： 赤井　一郎　教授（産業ナノマテリアル研究所）
                        Email：iakai@kumamoto-u.ac.jp

【IROASTセミナーに関するお問合せ】
佐藤
Email: szk-kiko@jimu.kumamoto-u.ac.jp

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IROAST will have the 108th IROAST Seminar by Dr. Marc de Boissieu (SiMAP-Grenoble Alpes University, France), as follows.
Anyone interested in this seminar is more than welcome. Registration is not required.
We hope to see you at the seminar.                      

1. Date and time: November 28 (Mon), 2023, 16:25 - 17:55
2. Venue: Room C122, Kurokami South E1 (Faculty of Science Bldg. 1 & 2)
   * Held online as well. (For Zoom information, please email IROAST.)
3. Speaker: Dr. Marc De Boissieu, Director, SiMAP-Grenoble Alpes University, France
4. Title & Abstract:：Referred to above
5. Organizer: Prof. Ichiro Akai (IINa, Kumamoto University)
                       E-mail: iakai@kumamoto-u.ac.jp

*Remarks: This seminar will be held in English.

IROAST Seminar inquiries
Sato (Ms.)
szk-kiko@jimu.kumamoto-u.ac.jp