九州大学-研究者情報 [麻生亮太郎 (准教授) 工学研究院エネルギー量子工学部門]

1.	Ryotaro Aso, Hajime Hojo, Yoshio Takahashi, Tetsuya Akashi, Yoshihiro Midoh, Fumiaki Ichihashi, Hiroshi Nakajima, Takehiro Tamaoka, Kunio Yubuta, Hiroshi Nakanishi, Hisahiro Einaga, Toshiaki Tanigaki, Hiroyuki Shinada, Yasukazu Murakami, Direct identification of the charge state in a single platinum nanoparticle on titanium oxide, Science, 10.1126/science.abq5868, 378, 202-206, 2022.10, A goal in the characterization of supported metal catalysts is to achieve particle-by-particle analysis of the charge state strongly correlated with the catalytic activity. Here, we demonstrate the direct identification of the charge state of individual platinum nanoparticles (NPs) supported on titanium dioxide using ultrahigh sensitivity and precision electron holography. Sophisticated phase-shift analysis for the part of the NPs protruding into the vacuum visualized slight potential changes around individual platinum NPs. The analysis revealed the number (only one to six electrons) and sense (positive or negative) of the charge per platinum NP. The underlying mechanism of platinum charging is explained by the work function differences between platinum and titanium dioxide (depending on the orientation relationship and lattice distortion) and by first-principles calculations in terms of the charge transfer processes..
2.	Ryotaro Aso, Yohei Ogawa, Takehiro Tamaoka, Hideto Yoshida, Seiji Takeda, Visualizing Progressive Atomic Change in the Metal Surface Structure Made by Ultrafast Electronic Interactions in an Ambient Environment, Angewandte Chemie - International Edition, 10.1002/anie.201907679, 58, 45, 16028-16032, 2019.11, [URL], Understanding the atomic and molecular phenomena occurring in working catalysts and nanodevices requires the elucidation of atomic migration originating from electronic excitations. The progressive atomic dynamics on metal surface under controlled electronic stimulus in real time, space, and gas environments are visualized for the first time. By in situ environmental transmission electron microscopy, the gas molecules introduced into the biased metal nanogap could be activated by electron tunneling and caused the unpredicted atomic dynamics. The typically inactive gold was oxidized locally on the positive tip and field-evaporated to the negative tip, resulting in the atomic reconstruction on the negative tip surface. This finding of a tunneling-electron-attached-gas process will bring new insights into the design of nanostructures such as nanoparticle catalysts and quantum nanodots and will stimulate syntheses of novel nanomaterials not seen in the ambient environment..
3.	Ryotaro Aso, Daisuke Kan, Yuichi Shimakawa, Hiroki Kurata, Control of structural distortions in transition-metal oxide films through oxygen displacement at the heterointerface, Advanced Functional Materials, 10.1002/adfm.201303521, 24, 33, 5177-5184, 2014.09, [URL], Structural distortions in the oxygen octahedral network in transition-metal oxides play crucial roles in yielding a broad spectrum of functional properties, and precise control of such distortions is a key for developing future oxide-based electronics. Here, it is shown that the displacement of apical oxygen atom shared between the octahedra at the heterointerface is a determining parameter for these distortions and consequently for control of structural and electronic phases of a strained oxide film. The present analysis by complementary annular dark- and bright-field imaging in aberration-corrected scanning transmission electron microscopy reveals that structural phase differences in strained monoclinic and tetragonal SrRuO₃ films grown on GdScO₃ substrates result from relaxation of the octahedral tilt, associated with changes in the in-plane displacement of the apical oxygen atom at the heterointerface. It is further demonstrated that octahedral distortions and magnetrotransport properties of the SrRuO₃ films can be controlled by interface engineering of the oxygen displacement. This provides a further degree of freedom for manipulating structural and electronic properties in strained films, allowing the design of novel oxide-based heterostructures..
4.	Ryotaro Aso, Daisuke Kan, Yuichi Shimakawa, Hiroki Kurata, Atomic level observation of octahedral distortions at the perovskite oxide heterointerface, Scientific reports, 10.1038/srep02214, 3, 2013.07, [URL], For perovskite oxides, ABO₃, slight octahedral distortions have close links to functional properties. While perovskite oxide heterostructures offer a good platform for controlling functionalities, atomistic understanding of octahedral distortion at the interface has been a challenge as it requires precise measurements of the oxygen atomic positions. Here we demonstrate an approach to clarify distortions at an atomic level using annular bright-field imaging in aberration-corrected scanning transmission electron microscopy, which provides precise mappings of cation and oxygen atomic positions from distortion-minimized images. This technique revealed significant distortions of RuO₆ and ScO₆ octahedra at the heterointerface between a SrRuO₃ film and a GdScO₃ substrate. We also found that structural mismatch was relieved within only four unit cells near the interface by shifting the oxygen atomic positions to accommodate octahedral tilt angle mismatch. The present results underscore the critical role of the oxygen atom in the octahedral connectivity at the perovskite oxide heterointerface..

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学会活動

所属学会名

日本顕微鏡学会

応用物理学会

学協会役員等への就任

2023.04～2024.04, 日本顕微鏡学会　学際的顕微研究領域若手研究部会, 会長.

学会大会・会議・シンポジウム等における役割

2023.06.25～2023.06.25, International symposium for young scientist in state-of-the-art microscopy, 主催者（責任者）.

受賞

令和６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, 2024.04.

第16回（令和４年度）風戸研究奨励賞, 公益財団法人風戸研究奨励会, 2023.02.

第33回（2016年度）井上研究奨励賞, 公益財団法人　井上科学振興財団, 2017.02.

第34回応用物理学会講演奨励賞, 公益財団法人　応用物理学会, 2013.09.

Poster Competition 1st PRIZE (Physical Sciences), The European Microscopy Society, 2012.09.

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)

2022年度～2025年度, 基盤研究(B), 分担, 遷移金属ダイカルコゲナイド原子層を酸化前駆体とする機能性酸化物超薄膜の創出.

2022年度～2024年度, 基盤研究(B), 分担, アニオン欠陥の自在制御による革新的酸素発生触媒の開拓.

2022年度～2023年度, 新学術領域研究, 代表, 高速高分解能マッピングによる蓄電固体界面のオペランド解析.

2022年度～2024年度, 基盤研究(C), 代表, 全固体電池界面の原子スケール低温その場観察.

2020年度～2021年度, 新学術領域研究, 代表, 環境制御した電子顕微鏡法による蓄電固体界面の局所構造解析.

2019年度～2021年度, 若手研究, 代表, 高速高分解能測定による原子分子ダイナミクスの実時間解析.

2015年度～2016年度, 若手研究(B), 代表, イオン化した気体分子による金属表面への吸着・衝突現象の動的解析.

競争的資金(受託研究を含む)の採択状況

2020年度～2023年度, 物質・デバイス領域共同研究拠点基盤共同研究, 代表, ガス反応を利用した機能性ナノ構造その場形成.

寄附金の受入状況

2023年度, 公益財団法人風戸研究奨励会, 風戸研究奨励賞（研究費助成）／高感度電子線ホログラフィーによるナノスケール電場解析.

2021年度, 公益財団法人木下記念事業団, 木下基礎科学研究基金助成／アニオン制御した機能性酸化物材料の原子・電子構造解析.

学内資金・基金等への採択状況

2021年度～2022年度, 工学研究新分野開拓助成, 代表, 歪み解析による酸化物ナノ結晶の電気分極に関する研究.

2021年度～2021年度, QRプログラム　わかばチャレンジ, 代表, 全固体電池界面のナノ構造解析に向けた低温その場観察法の開発.

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

工学部・工学研究院


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