University of the Ryukyus · Faculty of Science

Research keywordsion-conducting glasses・lithium ion transport・glass structure・alumina glass・thermal analysis・amorphous material diffraction

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• Lithium Ion Transport Environment by Molecular Vibrations in Ion‐Conducting Glasses2023 · Hiroki Yamada, Koji Ohara, Satoshi Hiroi, Atsushi Sakuda, Kazutaka Ikeda, Takahiro Ohkubo, Kengo Nakada, Hirofumi Tsukasaki, Hiroshi Nakajima, Laszlo Temleitner, Laszlo Pusztai, Shunsuke Ariga, Aoto Matsuo, Jiong Ding, Takumi Nakano, Takuya Kimura, Ryo Kobayashi, Takeshi Usuki, Shuta Tahara, Koji Amezawa, Yoshitaka Tateyama, Shigeo Mori, Akitoshi Hayashi
• Crystal Growth, Structural and Thermal Studies of FeC4H4O6·2.5H2O2022 · Single crystals of iron(II) tartrate hemi-pentahydrate, FeC4H4O6·2.5H2O, were grown by the gel method using silica gels. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on the single crystals. The space group symmetry (orthorhombic P212121) and structural parameters were determined at room temperature. The crystal structure consisted of slightly distorted FeO6 octahedra, C4H4O6 and H2O molecules, C4H4O6–Fe–C4H4O6 chains jointed by Fe–O bonds, and O–H···O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystal were found to occur in the temperature range of 300–1060 K. We inferred that the weight losses were caused by the evaporation of bound water molecules and the evolution of H2CO, CO, and O2 gases from C4H4O6 molecules, and that the black residue after decomposition was composed of triiron tetraoxide (Fe3O4) and carbon.
• Structure of alumina glass2022 · <title>Abstract</title>The fabrication of novel oxide glass is a challenging topic in glass science. Alumina (Al₂O₃) glass cannot be fabricated by a conventional melt–quenching method, since Al₂O₃ is not a glass former. We found that amorphous Al₂O₃ synthesized by the electrochemical anodization of aluminum metal shows a glass transition. The neutron diffraction pattern of the glass exhibits an extremely sharp diffraction peak owing to the significantly dense packing of oxygen atoms. Structural modeling based on X-ray/neutron diffraction and NMR data suggests that the average Al–O coordination number is 4.66 and confirms the formation of OAl₃ triclusters associated with the large contribution of edge-sharing Al–O polyhedra. The formation of edge-sharing AlO₅ and AlO₆ polyhedra is completely outside of the corner-sharing tetrahedra motif in Zachariasen’s conventional glass formation concept. We show that the electrochemical anodization method leads to a new path for fabricating novel single-component oxide glasses.
• ガラスにならないEr2O3液体が持つ特異構造2021 · 小山千尋 , 小原真司 , 田原周太 , 小野寺陽平 , 石川毅彦

• 新たな固体電解質の開発に向けた超イオン導電体の形成要因の研究2016 · 若手研究(B)
• 量子ビームと理論の連携による革新的イオン伝導不規則構造材料創製基盤の構築2016 · 基盤研究(B)
• 無容器溶融法による非平衡バルクガラス合成プロセスの研究2012 · 基盤研究(B)

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