Nanoscale Engineering of Compositional Modulations in Alloys and Composite Thin Film Oxides for Exploration of Their New Properties and Functionalities

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02610
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Tohoku University
• Principal Investigator: MATSUMOTO Yuji 東北大学, 工学研究科, 教授 (60302981)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 酸化物薄膜 / ナノ傾斜組成変調 / 光触媒 / 電池材料 / 強誘電体・磁性体

Outline of Final Research Achievements

After the three-year period in this research program, the outcomes include the following: (a) Mg:ZnO band gap-graded films were fabricated and their photochemical properties were found to depend on the gradient direction of the films. (b) La: LiCoO2(LCO) films were prepared with La atoms preferentially substituted for the Li site. The introduction of a composition gradient structure for La in a LCO film improved the charge-discharge cycle performance, while it deteriorated for the La-LCO compositionally uniform films. (c) Ir:(La, Sr)MnO3 (LSMO) films were still ferromagnetic. The saturation magnetization of Ir-LSMO whose Ir was uniformly doped over the films exhibited an oscillatory behavior as the doped Ir content increased. In contrast, the saturation magnetization of Ir-LSMO films with composition gradients of Ir along the growing direction, was enhanced, significantly larger than expected from a simple linear sum of the magnetization of each constituent thin minute layer.

Free Research Field

薄膜・表面界面

Academic Significance and Societal Importance of the Research Achievements

本研究では，酸化物薄膜材料を対象として，従来，強誘電体膜や金属の磁性膜に限られていた，電子やフォノン、イオンの拡散や伝搬、さらには波動関数の広がりと同程度の様々な“ナノスケールの組成変調”を有する薄膜をデザインすることで，単一組成のものとは異なる光電気化学特性や二次電池特性，さらには磁気特性が発現することを実験的に検証した。本成果は，“ナノスケールの組成変調”が材料設計の新しいコンセプトとして，今後，薄膜，バルク材料を問わず，産学における材料開発研究に積極的に取り入れられる契機となることが期待される。