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Development of Functional Mesocrystalline Materials and Ferroelectric Perovskites
https://kagawa-u.repo.nii.ac.jp/records/407
https://kagawa-u.repo.nii.ac.jp/records/407dc989066-bab4-46cc-af82-f2076db17453
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本文の要約 (6.6 MB)
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内容の要旨及び審査結果の要旨 (171.4 kB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||||||||
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| 公開日 | 2019-09-24 | |||||||||||
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| タイトル | Development of Functional Mesocrystalline Materials and Ferroelectric Perovskites | |||||||||||
| 言語 | en | |||||||||||
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| 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 | |||||||||||
| 著者 |
張, 文雄
× 張, 文雄
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| 内容記述タイプ | Abstract | |||||||||||
| 内容記述 | Mesocrystals, a new class of unique materials, not only have some potential properties based on the individual nanocrystals but also exhibit unique collective properties of nanocrystal ensembles. They have become a fascinating research area as a new class of materials for catalysis, sensing, and energy storage and conversion in the past decade. On the other hand, perovskite solar cells (PSCs) have attracted the great interest of the researchers due to their low-cost potentials on converting solar power to electrical power. However, its mysterious hysteresis behavior severely hampers further improvements of the materials for future developments. In the present dissertation, the ferroelectric, dielectric and piezoelectric properties of the ferroelectric mesocrystalline BaTiO3/Bi0.5Na0.5TiO3 (BT/BNT) and BaTiO3/ BaBi4Ti4O15 (BT/BBT) nanocomposites are greatly enhanced by the lattice strain engineering. We have found that the mesocrystalline nanocomposite is a promising material for strain engineering to improve the piezoelectric response because it has a high density of the heteroepitaxial interface. Besides, the Curie temperature of the BT/BNT and BT/BBT nanocomposites are also highly elevated, which broadens the application range of the materials. In addition, a detailed structural analysis and ferroelectric investigation of the CH3NH3PbI3-xClx perovskite used in PSCs are performed to understand the working mechanism of the PSCs. Ferroelectric semiconducting behavior of the material is uncovered and a clear charge transfer mechanism is defined. This dissertation is composed of five chapters as follows: In Chapter I, the general introductions to the mesocrystals and perovskite ferroelectric material for a solar cell including history, working mechanisms, materials properties, and characterization techniques are given. Furthermore, the purposes of this dissertation are also included. In Chapter II, a ferroelectric mesocrystalline BaTiO3/Bi0.5Na0.5TiO3 (BT/BNT) nanocomposite synthesized from a layered titanate H1.07Ti1.73O4 (HTO) by a facile two-step topochemical process is introduced. The BT/BNT nanocomposite is constructed from well-aligned BT and BNT nanocrystals with the same crystal-axis orientation. The BT/BNT heteroepitaxial interface in the nanocomposite is promising for the enhanced piezoelectric performance by using the lattice strain engineering, which gives a giant piezoelectric response with a d*33 value of 408 pm/V. The introduced lattice strain at the BT/BNT heteroepitaxial interface causes transitions of pseudo-paraelectric BT and BNT nanocrystals to the ferroelectric nanocrystals in the mesocrystalline nanocomposite, which enlarges ferroelectric, piezoelectric and dielectric responses. The lattice strain also results in the elevated Curie temperatures (Tc) of BT and BNT and a new intermediate phase transition. In Chapter III, a ferroelectric mesocrystalline BaTiO3/BaBi4Ti4O15 (BT/BBT) nanocomposite synthesized from a layered titanate H1.07Ti1.73O4 (HTO) by a facile two-step topochemical process is exhibited. The BT/BBT nanocomposite is constructed from well-aligned BT and BBT nanocrystals oriented along the [110] and [11-1] crystal-axis directions respectively. The lattice strain is introduced into the nanocomposite by the formation of the BT/BBT heteroepitaxial interface, which causes a greatly elevated Curie temperature from 400 to 700 °C and an improved piezoelectric response with d*33=130 pm/V. In addition, the BT/BBT nanocomposite is stable up to a high heating temperature of 1100 ºC, therefore the mesocrystalline ceramic can be fabricated as a high-performance ferroelectric material. In Chapter IV, the ferroelastic and antiferroelectric properties of the CH3NH3PbI3-xClx perovskites at room temperature are presented. And the ferroelectric hysteresis loops of the CH3NH3PbI3-xClx perovskites are analyzed with the assistance of the CIP and heat treatments for a reliable result. The anti-ferroelectric nature of the semiconducting CH3NH3PbI3-xClx perovskite has been clearly illustrated by using the piezoelectric response microscope system (PFM), which gives solid evidence for the argument between the non-ferroelectric and ferroelectric nature for the material at the room temperature and pave the way for the fabrication of high efficient perovskite solar cells. In Chapter V, a summary of this study is given. Importance of the study for future developments in functional mesocrystals and solar cells are also provided. |
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| 言語 | en | |||||||||||
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| 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 | 2019-03-24 | |||||||||||
| 学位授与番号 | ||||||||||||
| 学位授与番号 | 甲第137号 | |||||||||||
| KEID | ||||||||||||
| 28771 | ||||||||||||
