研究課題/領域番号 |
22K04686
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研究種目 |
基盤研究(C)
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配分区分 | 基金 |
応募区分 | 一般 |
審査区分 |
小区分26020:無機材料および物性関連
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研究機関 | 京都大学 |
研究代表者 |
YI Wei 京都大学, 工学研究科, 准教授 (50903431)
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研究期間 (年度) |
2022-04-01 – 2025-03-31
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研究課題ステータス |
交付 (2022年度)
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配分額 *注記 |
4,030千円 (直接経費: 3,100千円、間接経費: 930千円)
2024年度: 650千円 (直接経費: 500千円、間接経費: 150千円)
2023年度: 650千円 (直接経費: 500千円、間接経費: 150千円)
2022年度: 2,730千円 (直接経費: 2,100千円、間接経費: 630千円)
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キーワード | Polar metal |
研究開始時の研究の概要 |
The research will be carried out on layered perovskite oxides as following: (1) chemical doping by inequivalent cation substitution on B-site. (2) O-vacancy introduced by high pressure synthesis method. (3) determine ferroelectricity and metallicity phase diagram for doping system.
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研究実績の概要 |
Ferroelectric metals combining ferroelectricity and metallicity, two seemingly mutually exclusive properties in one system, strongly stirred the research community. Ferroelectrics with a spontaneous and reversible electric polarization, are promising for a wide range of applications and pose a number of fundamental questions. In general, they are insulators. Introducing itinerant charge carriers is expected to screen the long-range coulomb forces and quench ferroelectricity. This conventional concept was broken when the existence of ferroelectric-like metal was theoretically proposed by Anderson and Blount and the ferroelectric-like structural transition in metallic was experimentally observed in LiOsO3. Although several theoretical predictions of ferroelectric/polar metals have been reported, the experimental observations are still rather rare so far. The core issue of this project is to extend the members of this material family and research the unconventional properties of ferroelectric/polar metal materials. We have achieved two things in the fiscal year 2022 (FY2022). First, one new metallic transition metal oxide (same to LiOsO3) with ferroelectric-like structural transition at low temperature was successfully synthesized in polycrystalline form. Second, a series of carrier doped layered perovskite oxides with Ruddlesden-Popper type structure was prepared.
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現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
In FY2022, we achieved 50% of the final goal of this research project. One new transition metal oxide with LiNbO3-type structure has been prepared in the polycrystalline form. Its physical properties were examined by a series of characterizations: the polar structure at low temperature was demonstrated by the structure analyses using the synchrotron x-ray diffraction and neutron diffraction data of powder samples; the critical temperature of phase transition was suggested by the anomaly in the curve of specific heat vs temperature, the metallic conductivity was measured at variable temperature. For the carrier-doped layered perovskite oxides, characterizations of physical properties including electric conductivity in magnetic field at low temperatures suggested the magnetoresistance effect. The possibility of structure phase transition at low temperatures is being examined by the detailed structure analyses of polycrystalline samples using synchrotron x-ray diffraction.
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今後の研究の推進方策 |
For the future study in FY2023, we will continue the project and conduct detailed evaluations of physical properties and structures, such as the convergent-beam electron diffraction (CBED) perform to confirm the loss of inversion symmetry. The preparations and structure analyses of ferroelectric/polar metal compounds will be done in doped layered perovskites. We also aim to modulate the functionality of ferroelectric/polar metal materials by the doping carriers.
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