九州大学-研究者情報 [渡邉賢 (准教授) 総合理工学研究院物質科学部門]

1.	Hayashi, Naohiro; Watanabe, Ken; Shimanoe, Kengo , Low-temperature sintering characteristics and electrical properties of Ca- and Bi-doped Li7La3Zr2O12 electrolyte containing Li3BO3 additive, JOURNAL OF MATERIALS CHEMISTRY A, 10.1039/d2ta07747g, 11, 4, 2042-2053, 2023.01.
2.	Shingo Ide, Hiroki Takahashi, Isamu Yashima, Koichi Suematsu, Ken Watanabe, Kengo Shimanoe, Effect of Boron Substitution on Oxide-Ion Conduction in c-Axis-Oriented Apatite-Type Lanthanum Silicate, Journal of Physical Chemistry C, 10.1021/acs.jpcc.9b11454, 124, 5, 2879-2885, 2020.02, [URL], Apatite-type lanthanum silicate (LSO) is a material with high oxide-ion conductivity in the low- and intermediateerature range (573-873 K) and is, therefore, a promising solid electrolyte for lowerature applications such as solid oxide fuel cells and oxygen sensors. Herein, the effect of B substitution at the Si site in a c-axis-oriented apatite-type lanthanum silicate (La_9.7Si_5.3B_0.7O_26.2, c-LSBO) polycrystal on oxide-ion conduction is investigated. A highly c-axis-oriented LSBO polycrystal is fabricated by a vapor-solid reaction in which a dense La₂SiO₅ disk is heated in B₂O₃ vapor at ≥1673 K. The oxide-ion conductivity of c-LSBO reaches 16 mS cm^-1 at 678 K with an activation energy of 0.4 eV. The obtained oxide-ion conductivity of c-LSBO is approximately 190 times higher than that of yttria-stabilized zirconia and 5.8 times higher than that of the polycrystalline c-axis-oriented nondoped lanthanum silicate. Based on ¹¹B nuclear magnetic resonance measurements, B is located at the SiO₄ site as BO₄, suggesting the formation of an oxygen vacancy at the O4 site located along the c-axis due to charge compensation. In addition, molecular dynamics simulations indicate that the oxide-ion diffusion coefficient of the B-doped LSO is higher than that of the nondoped LSO. The high oxide-ion conductivity of c-LSBO is likely attributable to the formation of an oxygen vacancy at the O4 site by B doping, which has a lower valency than Si. Therefore, c-LSBO is a promising candidate as a solid electrolyte in electrochemical devices operating at low and moderately high temperatures..
3.	Ken Watanabe, Isao Sakaguchi, Minako Hashiguchi, Noriko Saito, Emily M. Ross, Hajime Haneda, Takeo Ohsawa, Naoki Ohashi, Isotope tracer investigation and ab-initio simulation of anisotropic hydrogen transport and possible multi-hydrogen centers in tin dioxide, Journal of Applied Physics, 10.1063/1.4953387, 119, 22, 2016.06, [URL], Hydrogen as an impurity in single crystals of tin dioxide was investigated through diffusivity and vibrational-mode analyses performed using isotope tracers and density functional theory calculations. It was found that hydrogen diffusion along the 001 axis is very fast, even at relatively low temperatures (400 ï¿½C), but is considerably slower within the (001) plane. Using transitional state calculations, this diffusion behavior was determined to be the result of anisotropy in the migration barrier for interstitial hydrogen (H_i). In addition, the two distinct vibrational modes observed in the optical spectrum were identified as the O-H stretching modes of Hi and the substitutional hydrogen at the tin sites..
4.	Ken Watanabe, Takeo Ohsawa, Isao Sakaguchi, Oliver Bierwagen, Mark E. White, Min Ying Tsai, Ryosuke Takahashi, Emily M. Ross, Yutaka Adachi, James S. Speck, Hajime Haneda, Naoki Ohashi, Investigation of charge compensation in indium-doped tin dioxide by hydrogen insertion via annealing under humid conditions, Applied Physics Letters, 10.1063/1.4870425, 104, 13, 2014.03, [URL], The behavior of hydrogen (H) as an impurity in indium (In)-doped tin dioxide (SnO₂) was investigated by mass spectrometry analyses, with the aim of understanding the charge compensation mechanism in SnO₂. The H-concentration of the In-doped SnO₂ films increased to (1-2)×10¹⁹cm^-3 by annealing in a humid atmosphere (WET annealing). The electron concentration in the films also increased after WET annealing but was two orders of magnitude less than their H-concentrations. A self-compensation mechanism, based on the assumption that H sits at substitutional sites, is proposed to explain the mismatch between the electron- and H-concentrations..
5.	Ken Watanabe, Isao Sakaguchi, Shunichi Hishita, Naoki Ohashi, Hajime Haneda, Visualization of grain boundary as blocking layer for oxygen tracer diffusion and a proposed defect model in non doped BaTiO₃ ceramics, Applied Physics Express, 10.1143/APEX.4.055801, 4, 5, 2011.05, [URL], We performed visualization of the oxygen diffusion path in oxidized and reduced BaTiO₃ ceramics by utilizing an ion-imaging technique. The oxygen tracer diffused quickly from the surface up to the grain boundary, and then behaved as discontinuous steps at the grain boundary. The grain boundary acted as a blocking layer against oxygen diffusion. The reduction process enhanced the blocking effect. The blocking of oxygen diffusion at the grain boundary originated in the formation and distribution of complex defects between the charged oxygen vacancy and the reduced Ti near the grain boundary..
6.	Watenabe, Ken; Yuasa, Masayoshi; Kida, Tetsuya; Teraoka, Yasutake; Yamazoe, Noboru; Shimanoe, Kengo, High-Performance Oxygen-Permeable Membranes with an Asymmetric Structure Using Ba0.95La0.05FeO3-delta Perovskite-Type Oxide, ADVANCED MATERIALS, 10.1002/adma.200903953, 22, 21, 2367-2370, 2010.06.
7.	Ken Watanabe, Masayoshi Yuasa, Tetsuya Kida, Kengo Shimanoe, Yasutake Teraoka, Noboru Yamazoe, Dense/porous asymmetric-structured oxygen permeable Membranes based on la_0.6Ca_0.4CoO₃ perovskite-type oxide, Chemistry of Materials, 10.1021/cm8013144, 20, 22, 6965-6973, 2008.11, [URL], To achieve high-efficiency oxygen permeation using mixed (ionic and electronic) conducting perovskite-type oxides, we examined asymmetric-structured membranes of La_0.6Ca_0.4CoO₃ in which a thin dense membrane was deposited on a porous support. The La_0.6Ca _0.4CoO₃ porous support was fabricated using irregular-shaped precursor particles prepared through an oxalate method. The fabricated support had good gas permeability and thermal stability, showing sufficient properties as a support for dense thin membranes. A dense membrane of 10 μm thickness was successfully formed on the porous support by coating a La_0.6Ca_0.4CoO₃ slurry and subsequent densification by sintering. The deposited thin membrane was gastight and free from clacks, as revealed by gas permeation tests and SEM observations. The asymmetric membrane exhibited a high oxygen permeability of 1.66 cm³ (STP, standard temperature and pressure) min^-1 cm^-2 at 930 °C, which was four times higher than that of a typical sintered-disk type membrane with 1200 μm thickness, demonstrating its feasibility as a high-performance oxygen separation membrane..

主要総説, 論評, 解説, 書評, 報告書等

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主要学会発表等

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1.	Ken Watanabe, Koichi Suematsu, Kengo Shimanoe, Low temperature sintering of garnet-type Li7La3Zr2O12 for all solid state Li-ion battery, OptoX-NANO 2019, 2019.12.
2.	Ken Watanabe, Challenge toward co-sintering of all solid-state Li ion battery based on oxides, The 11th International Conference on the Science and Technology for Advanced Ceramics, 2019.07.
3.	Ken Watanabe, Shingo Ide, Koichi Suematsu, Kengo Shimanoe, New concept of solid electrolyte gas sensor based on oxide-ionic conductor, 22th international Conference on Solid State Ionics, 2019.06.
4.	K. Watanabe, Material design for an electrode of oxygen pumps based on oxide-ion conductors, CIMTEC2018 (14th International Ceramics Congress), 2018.06.
5.	吉野嵩啓, 渡邉賢, 末松昂一, 西堀麻衣子, 島ノ江憲剛, Li-B系酸化物を用いたLi₇ La₃ Zr₂O₁₂ の低温焼結, 第 56 回セラミックス基礎科学討論会プログラム, 2018.01.
6.	K. Watanabe, Material design for gas sensor based on defect in metal oxide semiconductor, the 7th edition of the Gospel Workshop, 2017.11.
7.	K. Watanabe, Hydrogen in Metal oxides semiconductor, TVS-2017, 2017.10.

特許出願・取得

特許出願件数 1件

特許登録件数 0件

学会活動

所属学会名

日本固体イオニクス学会

日本化学会

電気化学会

日本セラミックス協会

化学センサ研究会

学協会役員等への就任

2022.01～2023.12, 電気化学会九州支部, 役員.

2021.03～2023.03, 電気化学会, 電気化学　編集部　編集委員会.

2021.04～2027.03, 日本セラミックス協会, 行事企画委員.

学会大会・会議・シンポジウム等における役割

2022.03.10～2022.03.12, 日本セラミックス協会　2022年年会, プログラム編成委員.

2018.11.14～2018.11.16, 第58回電池討論会, 現地実行委員.

学会誌・雑誌・著書の編集への参加状況

2021.03～2023.03, 電気化学, 国内, 編集委員.

学術論文等の審査

年度	外国語雑誌査読論文数	合計
2021年度	10	10
2020年度	14	14
2018年度	6	6
2017年度	2	2
2016年度	2	2

受賞

奨励賞, 日本セラミックス協会　電子材料部会, 2021.11.

研究奨励賞, 九州ファインセラミックス・テクノフォーラム, 2021.06.

2019年JCS-JAPAN優秀論文賞, 日本セラミックス協会, 2020.05.

平成31年度科学技術分野の文部科学大臣表彰若手科学者賞, 文部科学省, 2019.04.

研究資金

科学研究費補助金の採択状況(文部科学省、日本学術振興会)

2019年度～2021年度, 基盤研究(B), 分担, 高選択性pptレベルマイクロガスセンサのための材料設計構築.

2017年度～2021年度, 基盤研究(C), 分担, ピラミッド型酸化亜鉛粒子のガスセンサ特性.

2016年度～2018年度, 基盤研究(B), 分担, ダブルレセプター機能によるバイオマーカーガスのppbレベル検知.

2014年度～2016年度, 基盤研究(C), 分担, 酸化亜鉛粒子の階層構造を利用したＶＯＣガスセンサ.

2011年度～2013年度, 基盤研究(B), 分担, 酸化物イオン導電性膜の構造設計と高効率酸素分離.

共同研究、受託研究(競争的資金を除く)の受入状況

2021.03～2022.03, 代表, 硫化物全固体Liイオン二次電池用正極材料に関する研究.

寄附金の受入状況

2021年度, リチウムイオン伝導体材料の学術教育研究.

九大関連コンテンツ

pure2017年10月2日から、「九州大学研究者情報」を補完するデータベースとして、Elsevier社の「Pure」による研究業績の公開を開始しました。

QIR　九州大学学術情報リポジトリシステム情報科学研究院

総合理工学研究院


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