研究领域

Chemical Crystallography/Solid-State Chemistry

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).

近期论文

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Defect induced sodium disorder and ionic conduction mechanism in Na1.82Mg1.09P2O7. Guandong Liu, Shin-ichi Nishimura, Sai Cheong Chung, Kotaro Fujii, Masatomo Yashima, Atsuo Yamada. J. Mat. Chem. A, 2(43), 18353-18359, (2014). New Perovskite-Related Structure Family of Oxide-Ion Conducting Materials NdBaInO4. Kotaro Fujii, Yuichi Esaki, Kazuki Omoto, Masatomo Yashima, Akinori Hoshikawa, Toru Ishigaki, James R. Hester. Chem. Mater., 26(8), 2488-2491, (2014). Crystal structures of a pentavalent bismuthate, SrBi2O6 and a lead bismuth oxide (Pb1/3Bi2/3)O1.4. Nobuhiro Kumada, Akira Miura, Takahiro Takei, Masatomo Yashima. J. Asian Ceram. Soc., 2(2), 150-153, (2014). Diffusion Path and Conduction Mechanism of Protons in Hydroxyapatite. Masatomo Yashima, Naoyuki Kubo, Kazuki Omoto, Hirotaka Fujimori, Kotaro Fujii, Kenji Ohoyama. J. Phys. Chem. C, 118(10), 5180-5187, (2014). Structural Origin of the Anisotropic Thermal Expansion of a K2NiF4-Type Oxide CaErAlO4 through Interatomic Distances. Kazuki Omoto, Masatomo Yashima, James R. Hester. Chem. Lett., 43(4), 515-517, (2014). Origin of anisotropic thermal expansion in CaYAlO4. Kazuki Omoto, Masatomo Yashima. Appl. Phys. Express, 7(3), 037301, (2014). Crystal Structure, Optical Properties, and Electronic Structure of Calcium Strontium Tungsten Oxynitrides CaxSr1–xWO2N. Masatomo Yashima, Uhi Fumi, Hiromi Nakano, Kazuki Omoto, James R. Hester. J. Phys. Chem. C, 117(36), 18529-18539, (2013). Experimental Visualization of the Diffusional Pathway of Oxide Ions in a Layered Perovskite-type Cobaltite PrBaCo2O5+δ. Yi-Ching Chen, Masatomo Yashima, Juan Peña-Martínez, John A. Kilner. Chem. Mater., 25(13), 2638-2641, (2013). Invited Review “Crystal and Electronic Structures, Structural Disorder, Phase Transformation, and Phase Diagram of Ceria-Zirconia and Ceria-Based Materials”. Masatomo Yashima. Chapter 1, pp.1-45 in Catalysis by Ceria and Related Materials 2nd Edition(ed. A. Trovarelli and P. Fornasiero), Catalytic Science Series, (Vol. 12). Experimental visualization of the Bi–O covalency in ferroelectric bismuth ferrite (BiFeO3) by synchrotron X-ray powder diffraction analysis. Kotaro Fujii, Hiroki Kato, Kazuki Omoto, Masatomo Yashima, Jun Chen, Xianran Xing. Phys. Chem. Chem. Phys., 15(18), 6779-6782, (2013). Crystal Structure and Oxide-Ion Diffusion of Nanocrystalline, Compositionally Homogeneous Ceria–Zirconia Ce0.5Zr0.5O2 up to 1176 K. Masatomo Yashima, Tomohiro Sekikawa, Daisuke Sato, Hiromi Nakano, Kazuki Omoto. Cryst. Growth & Des., 13(2), 829-837, (2013). Origin of the Ferrielectricty and Visible-Light Photocatalytic Activity of Silver Niobate AgNbO3. Masatomo Yashima, Shota Matsuyama. J. Phys. Chem. C, 116(47), 24902–24906, (2012). Role of Ga3+ and Cu2+ in the High Interstitial Oxide-Ion Diffusivity of Pr2NiO4-Based Oxides: Design Concept of Interstitial Ion Conductors through the Higher-Valence d10 Dopant and Jahn–Teller Effect. Masatomo Yashima, Hiroki Yamada, Sirikanda Nuansaeng, Tatsumi Ishihara. Chem. Mater., 24(21), 4100-4113, (2012). Crystal Structure, Oxygen Deficiency, and Oxygen Diffusion Path of Perovskite-Type Lanthanum Cobaltites La0.4Ba0.6CoO3−δ and La0.6Sr0.4CoO3−δ. Yi-Ching Chen, Masatomo Yashima, Takashi Ohta, Kenji Ohoyama, Shinji Yamamoto. J. Phys. Chem. C, 116(8), 5246-5254, (2012). Experimental Visualization of Chemical Bonding and Structural Disorder in Hydroxyapatite through Charge and Nuclear-Density Analysis. Masatomo Yashima, Yukihiko Yonehara, Hirotaka Fujimori. J. Phys. Chem. C, 115(50), 25077–25087, (2011). Evidence for (Bi,Pb)–O Covalency in the High TC Ferroelectric PbTiO3–BiFeO3 with Large Tetragonality. Masatomo Yashima, Kazuki Omoto, Jun Chen, Hiroki Kato, Xianran Xing. Chem. Mater., 23(13), 3135–3137, (2011). Structural analysis of Li2TiO3 by synchrotron X-ray diffraction at high temperature. Kazuki Omoto, Takuya Hashimoto, Kazuya Sasaki, Takayuki Terai, Tsuyoshi Hoshino, Masatomo Yashima. J. Nucl. Mater., 417(1-3), 692–695, (2011). Structure of Ferroelectric Silver Niobate AgNbO3. Masatomo Yashima, Shota Matsuyama, Rikiya Sano Mitsuru Itoh, Kenji Tsuda, Desheng Fu. Chem. Mater., 23(7), 1643–1645, (2011).