2020 Fiscal Year Final Research Report
Ferroelectric nano-ordering and fractal nature in ferroelectric nanocrystals
| Project/Area Number |
18K03476
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 13020:Semiconductors, optical properties of condensed matter and atomic physics-related
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| Research Institution | Hokkaido University |
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Principal Investigator |
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | 強誘電性ナノ結晶 / 強誘電的ナノ秩序化 / 強誘電性ナノ秩序形成ダイナミクス / 高分解能広帯域光散乱分光 / トロイダル強誘電性 / フラクタル / 超臨界水熱合成法 / チタン酸鉛 |
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| Outline of Final Research Achievements |
In the present study, the crossover from the ferroelectric phase transition to the ferroelectric nano-ordering phenomenon and the fractal nature (self-similarity) in the nano-ordering process were investigated from the viewpoint of phonon dynamics by minimizing ferroelectric crystals to nanometer size. The temperature dependence of the broadband spectra mainly due to Raman susceptibility and the hyper-Rayleigh scattering spectra due to the presence of a 2nd-order nonlinear susceptibility were observed in high-quality lead titanate nanocrystals and barium titanate nanocrystals prepared by supercritical hydrothermal synthesis using a high-resolution broadband light scattering spectroscopy, as well as the size dependence of ferroelectric nanocrystalline particles. The relationship between ferroelectric nano-ordering and fractal nature was clarified by spectral analysis.
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| Free Research Field |
誘電体物理学
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| Academic Significance and Societal Importance of the Research Achievements |
協力現象について巨視的なスケールからナノメータ領域に至るサイズ効果は十分な解明がこれまでなされていない。主な理由として理論的には大きな自由度と境界条件の取り扱いの難しさ、また実験的には本質的な物性が評価できる良質なナノ結晶試料の作製の難しさにある。本研究では超臨界水熱合成法で作製された極めて良質な強誘電性ナノ結晶試料について高分解能広帯域光散乱分光を用いることで強誘電性ナノ秩序化現象の物理的発現機構の解明に重要な知見を得ることに成功し、本研究成果は「強誘電体の臨界サイズの問題」に対して物理学的起源の解明に重要な知見を与えた。
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