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Study on Ferroelectric Mesocrystalline Perovskite Materials with Enhanced Piezoelectric Response
https://kagawa-u.repo.nii.ac.jp/records/415
https://kagawa-u.repo.nii.ac.jp/records/4157e073c62-6df9-43fe-97c5-55af794aae4e
| 名前 / ファイル | ライセンス | アクション |
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本文の要約 (148.4 kB)
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内容の要旨・審査結果の要旨 (158.9 kB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||||||||
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| 公開日 | 2020-04-02 | |||||||||||
| タイトル | ||||||||||||
| タイトル | Study on Ferroelectric Mesocrystalline Perovskite Materials with Enhanced Piezoelectric Response | |||||||||||
| 言語 | en | |||||||||||
| 言語 | ||||||||||||
| 言語 | eng | |||||||||||
| 資源タイプ | ||||||||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_db06 | |||||||||||
| 資源タイプ | doctoral thesis | |||||||||||
| その他（別言語等）のタイトル | ||||||||||||
| その他のタイトル | 強誘電性メソクリスタルペロブスカイト材料及び圧電応答向上効果に関する研究 | |||||||||||
| 言語 | ja | |||||||||||
| アクセス権 | ||||||||||||
| アクセス権 | open access | |||||||||||
| アクセス権URI | http://purl.org/coar/access_right/c_abf2 | |||||||||||
| 著者 |
趙, 衛星
× 趙, 衛星
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| 抄録 | ||||||||||||
| 内容記述タイプ | Abstract | |||||||||||
| 内容記述 | Mesocrystals, as an abbreviation of mesoscopically structured crystal, are a new classification of nanostructured solid materials, which are composed of individual nanocrystals that are aligned along a common crystallographic direction. Although the mesocrystal is a polycrystal, it possesses both single crystal like properties, such as uniform crystal orientation and high crystallinity, and polycrystal properties, such as crystal interface and porosity. Therefore, the mesocrystalline materials have potential applications to the functional materials for catalysts, senses, ferroelectric and piezoelectric devises, and solar cells. Since the mesocrystalline material is a new research field, its properties and behavior remain almost unexplained. In the present dissertation, creation of various ferroelectric mesocrystalline materials, including Bax(Bi0.5Na0.5)1-xTiO3 (BBNT) mesocrystals, mesocrystalline nanocomposites of BaTiO3/Bi0.5K0.5TiO3 (BT/BKT) and SrTiO3/CaTiO3 (ST/CT), and characterizations of their nanostructures, ferroelectric, piezoelectric and dielectric behaviors are described. These mesocrystalline materials can be synthesized by using topochemical structural transformation processes from a layered titanate H1.07Ti1.73O4·nH2O (HTO) precursor. They exhibit special ferroelectric behavior. The heteroepitaxial interfaces are formed in the mesocrystalline nanocomposites of BT/BKT and ST/CT, which introduces a crystal lattice strain at the heteroepitaxial interfaces resulting enhanced piezoelectric and dielectric responses. The results suggest that the mesocrystalline nanocomposites are promising materials for the application of lattice strain engineering to improve the piezoelectric response. This dissertation is composed of five chapters as follows: In Chapter I, the general introductions to the ferroelectric, piezoelectric, and dielectric materials, ferroelectric perovskite materials, the properties, synthesis processes, and applications of mesocrystalline materials, and methods for enhancement of ferroelectric, piezoelectric, and dielectric responses. Furthermore, the purposes of this dissertation are also presented. In Chapter II, synthesis and nanostructure of the BBNT perovskite mesocrystal are mentioned. The BBNT perovskite mesocrystal was synthesized by a two-step topochemical process for the first time. In the first step, a layered titanate HTO precursor was solvothermally treated in Ba(OH)2 solution to obtain a BaTiO3/HTO (BT/HTO) nanocomposite. In the second step, the BT/HTO nanocomposite was hydrothermally treated in a mixed BiCl3-NaOH solution to obtain BBNT mesocrystal. The platelike BBNT mesocrystal was constructed from [110]-oriented BBNT nanocrystals with crystal sizes of about 30 nm. All BBNT nanocrystals in one platelike BBNT mesocrystal showed the same orientation in the [110]-direction. The reactions for the formation of BT/HTO nanocomposite from HTO precursor and BBNT mesocrystal from BT/HTO nanocomposite are topochemical reactions, which retains the platelike morphology of the HTO precursor particle during synthesis. In Chapter III, the studies are carried out on synthesis, piezoelectric and dielectric behaviors of mesocrystalline BT/BKT nanocomposite. This nanocomposite can be synthesized via a two-step topochemical process. In the first step, the BT/HTO nanocomposite was synthesized from HTO precursor by solvothermal reaction. In the second step, a BT/HTO-Bi2O3-K2CO3 mixture was heat-treated to obtain BT/BKT nanocomposite. The formation reaction of BT/BKT nanocomposite is a solid state topochemical reaction. Nanostructural analysis reveals that the BT/BKT nanocomposite is constructed from well-aligned [110]-oriented BT nanocrystals and [001]-oriented BKT nanocrystals. In the nanocomposite, a 2-dimensional heteroepitaxial interface of BT(001)/BKT(100) is formed, which introduces a lattice strain at the interface owing to their lattice mismatch. The BT/BKT nanocomposite exhibits much larger d33* and εr values than those of individual BT and BKT mesocrystals. The enlarged piezoelectric and dielectric responses demonstrate the potentials application of lattice strain engineering to mesocrystalline nanocomposites for high performance lead-free piezoelectric materials. In Chapter IV, a new type of mesocrystalline nanocomposite, ST/CT is described. This mesocrystalline nanocomposite can be synthesized by a two-step topochemical process from the HTO precursor. Firstly, a SrTiO3/HTO (ST/HTO) nanocomposite was synthesized by solvothermal treatment of the HTO precursor in a Sr(OH)2-NaOH mixed solution. Secondly, the ST/HTO nanocomposite was solvothermally treated in a Ca(OH)2-NaOH mixed solution to obtain ST/CT nanocomposite. The reactions in the formation process of ST/CT nanocomposite are also topochemical reactions. The ST/CT nanocomposite is constructed from well-aligned [110]-oriented ST nanocrystals and [001]-oriented CT nanocrystals, where a 3-dimensional heteroepitaxial interface is formed. The large piezoelectric response and an elevated Curie temperature (Tc) were achieved by construction of the 3-dimensional heteroepitaxial interface. It is notable fact that the Tc of ST phase was elevated from -250 oC to 300 oC, resulting a ferroelectric ST phase in ST/CT nanocomposite at room temperature. In Chapter V, a summary of the present study is given. The contributions of this study to the future developments in functional mesocrystals and lead-free piezoelectric materials are mentioned. |
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| 言語 | en | |||||||||||
| 学位名 | ||||||||||||
| 言語 | ja | |||||||||||
| 学位名 | 博士（工学） | |||||||||||
| 学位授与機関 | ||||||||||||
| 識別子Scheme | kakenhi | |||||||||||
| 識別子 | 16201 | |||||||||||
| 言語 | ja | |||||||||||
| 機関名 | 香川大学 | |||||||||||
| 言語 | en | |||||||||||
| 機関名 | Kagawa University | |||||||||||
| 学位授与年月日 | ||||||||||||
| 学位授与年月日 | 2020-03-24 | |||||||||||
| 学位授与番号 | ||||||||||||
| 学位授与番号 | 甲第140号 | |||||||||||
| 著者版フラグ | ||||||||||||
| 出版タイプ | VoR | |||||||||||
| 出版タイプResource | http://purl.org/coar/version/c_970fb48d4fbd8a85 | |||||||||||
| KEID | ||||||||||||
| 28863 | ||||||||||||
