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YASHIMA Laboratory



Professor :
Dr. Masatomo YASHIMA
Office : Room#410 of West 4th Building (Mail Box W4-17)
Phone # : +81-3-5734-2225
e-mail : yashima(at)cms.
Lectures Crystal Structure and Correlation with Material Properties(Graduate Schools), Scope of Chemistry and Materials Science (Graduate Schools), Chemistry 2 (Undergraduate School), Condensed Matter Chemistry (Undergraduate School).
Research Field : Materials Science, Crystal Structure and Properties of Inorganic Materials, Crystallography, Physical Chemistry, Inorganic Chemistry, Solid-State Chemistry
Education and Degree :
1982-1986 College of Natural Sciences, First Cluster of Colleges, Tsukuba University, Tsukuba, Japan (B. S.)
1986-1991 Graduate Course at Department of Materials Science and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Japan (M. S., and Doctor of Science in Engineering)
Professional Career :
1991-1995: Research Associate at Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Yokohama, Japan
1995-1997: Research Associate at Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Japan
1997-2011: Associate Professor at Department of Materials Science and Engineering, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama, Japan
1999-2000: Guest Professor at the Competence Center for Catalysis, Chalmers University of Technology, Gotenburg, Sweden
2011-present: Professor at Department of Chemistry and Materials Science, Tokyo Institute of Technology, Tokyo, Japan
Academic Activities : Crystallographic Society of Japan / Committee of Powder Diffraction of the International Union of Crystallography / International Center for Diffraction Data / Ceramic Society of Japan / Japan Institute of Metals / Chemical Society of Japan / Neutron Science Society of Japan

Assistant Professor :Dr. Kotaro FUJII
Office : Room#405 of West 4th Building (Mail Box W4-17)
Tel : 2331
e-mail : kfujii(at)cms.
Lectures :
(Department of Chemistry, Undergraduate)Chemistry Laboratory I&II
Research Field : Chemical Crystallography, Solid-State Chemistry
Degree : Mar. 2009 Dr. Sci. Tokyo Institute of Technology
Career : 2009 - 2010 Postdoctoral Researcher, Cardiff University(UK), 2010-2012 Postdoctoral Researcher, Tokyo Institute of Technology
Adjunct Assistant Professor :Dr. Eiki NIWA
Office : Room#405 of West 4th Building (Mail Box W4-17)
Tel : 2331
e-mail : niwa.e.aa(at)m.
Research Field : Solid-state chemistry, Electrochemistry, Thermodynamics. Kinetics
Degree : Sep. 2010 Dr. Eng. Tohoku University
Career : 2010-2013 Postdoctoral Researcher, Nihon Univ., 2013-2015 Assistant Professor, Nihon Univ.

Laboratory Home Page

Yashima Laboratory

Research Fields

Structure Analysis at High Temperatures and Structure-Based Material Design. From Basics to Applications.
In the world, there are many problems in various fields such as energy, environments, medicine and electronics. To solve these problems, the developments of inorganic materials are required. For this purpose it is of vital importance to investigate the crystal structure and electronic sate of materials. Namely the key to develop the materials to solve the problems in current technologies and societies is the study of the atomic arrangements and electron/nuclear density distributions in inorganic materials. Our group has been investigating the atomic structure and electron/nuclear density distributions of various materials through the advanced techniques for accurate crystal structure analysis. We examine not only high-purity samples but also industrial materials.
Many materials are prepared by heating at high temperatures. Many materials (Solid Oxide Fuel Cells (SOFCs), sensors and refractory) are utilized at high temperatures. Thus, the accurate structure analysis is needed for the materials kept at high temperatures. But, the previous structure studies through high-temperature diffractometry were not precise enough to discuss the structure-property correlation of many important materials (ex. diffusion mechanism in ionic conductors). Our group has designed, fabricated and developed new unique high-temperature systems for accurate structure analysis (Figs. 1a and 1b) and succeeded in the accurate structure analysis of numerous materials at high temperatures. Furthermore we are designing and creating new materials based on the crystal and electronic structures. Now the high-temperature structure analysis techniques have been established, which would lead to significant advance in our research works and to breakthrough in Chemistry and Materials Science.

(1) Developments of High-Temperature Accurate Structure-Analysis Systems: We are developing unique systems for excellent research works by ourselves!
Prof. Yashima's laboratory designed, fabricated and developed three "high-temperature accurate structure analysis systems" (Figs. 1a, b). These systems have enabled to obtain interesting scientific results which are first examples in the world or in Japan. We are able to determine accurately the spatial distributions of atoms, ions and electrons during heating the samples in air at high temperatures up to 1900 K. Consequently we have been establishing a new research field, "Accurate structure analysis at high temperatures".

Figure 1. High-temperature diffraction systems, which were developed by Prof. Yashima and collaborators. (a) High-temperature furnace installed at the goniometer of the synchrotron powder diffractometer of BL-4B2@KEK. (b) High-temperature furnace installed on the sample stage of the neutron powder diffractometer HERMES (Tohoku Univ.) at the research reactor JRR-3M (d). (c) Prof. Yashima's laboratory members who investigate the crystal structure and electron/nuclear density distributions of materials and develop the materials (March 2011).

(2) Research of positions and motions of ions and atoms in materials: Neutron diffraction experiments
Ionic conduction & atomic transport in solid materials are central theme of chemistry and physics in current science and technology, because ionic conductors are the key materials for energy and green societies. We are investigating the positions and motions of mobile ions in ionic conductors by neutron and synchrotron powder diffraction techniques. Our group has succeeded in the visualization of diffusional pathways of mobile ions in the lanthanum gallate-based phase for Solid Oxide Fuel Cells (SOFCs) (Fig. 2(a)), in bismuth oxide solid solution (One material with highest oxide-ion conductivity, Fig. 2(b)) and lithium-ion conducting materials. We have been investigating the crystal structure and phase transition of nano-particles, catalysts and ferroelectric materials. We also design new ionic conductors based on the knowledge of crystal structure.

Figure 2. Our group has succeeded in the visualization of diffusional pathways of mobile ions in the lanthanum gallate-based phase for Solid Oxide Fuel Cells (SOFCs) (1665 K, White line with arrows in Fig. 2(a)), in bismuth oxide solid solution (1019 K, Fig. 2(b)). (c) Electron-density distribution of the Perovskite CaTiO3. Experimental visualization of the Ti-O covalent bonding (1674 K). The covalent bonds are formed by the overlap of Ti 3d and O 2p orbitals.

(3) Experimental visualization of covalent bonds: Synchrotron powder diffraction experiments. Structure analysis of advanced materials with complicated structure. Material design based on crystal and electronic structures.
The material properties are correlated with the chemical bonding. In a compound, the covalent and ionic bonds coexist. The spatial arrangement of these chemical bonds is visualized by the electron-density analysis through x-ray diffraction experiments. Figure 2(c) shows the electron-density distribution of the Perovskite (CaTiO3) from the in situ synchrotron powder diffraction data measured at 1674 K. The Ti-O covalent bonds are experimentally visualized.
The decomposition of water by photocatalysts is an attractive way for clean and recyclable hydrogen production. We have been investigating the structural origin of the visible-light response of various photocatalysts through synchrotron X-ray and neutron powder diffractometry and first-principles band calculations. We also design new photocatalysts based on the knowledge of crystal structure.
Our group also studies the crystal and electronic structures of biomaterials. The high-angular-resolution of the synchrotron powder diffractometer shown in Fig. 1(a) enables to analyze the complicated structure of biomaterials.

Research TopicsF

Message from the Laboratory

To become an excellent scientist, researcher and/or engineer:
Important points for a graduate student are (1) to make their research plans by himself or herself, (2) to carry out their research by himself or herself and (3) to publish papers in high-impact journals and to present his or her works in international conferences. To accomplish these important tasks, Prof. Yashima and his laboratory are doing best. In the laboratory seminar, we are doing the literature and research reports. The fruitful discussion among students and professors is often done. The research report is done once two weeks in English. All the graduate students are doing best to obtain good results and to publish them in high-impact journals and to present their research results in international and domestic conferences. To obtain high-quality neutron and synchrotron powder diffraction data, we are often utilizing advanced and large facilities such as JRR-3M research reactor (Figures 1(b) and 1(d)), J-Parc, photon factory (PF, Figure 1(a)), and SPring-8. A graduate student has his/her own research project. In the neutron and synchrotron experiments, all the students are cooperating. Our research of accurate structure analysis is based on (1) preparation of high-purity samples, (2) experiments and measurements, (3) analysis of the data and (4) computer simulation. Research results by students are sometimes reported by the newspapers. Students won various awards (Best Poster Award in 3rd International Congress of Ceramics, Best Poster Award of the Crystallographic Society of Japan, Best presentation award in the department of Materials Science and Engineering). We like the after-hours drinking party to improve the interpersonal communication (once or twice three months).