2022 Fiscal Year Annual Research Report
Bismuth titanate-based high temperature piezoceramics: Domain structure and polarization dynamics
| Project/Area Number |
21F21704
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| Allocation Type | Single-year Grants |
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| Research Institution | Kyushu University |
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Principal Investigator |
陳 強 九州大学, 工学研究院, 教授 (30264451)
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| Co-Investigator(Kenkyū-buntansha) |
XIE SHAOXIONG 九州大学, 工学(系)研究科(研究院), 外国人特別研究員
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| Project Period (FY) |
2021-11-18 – 2024-03-31
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| Keywords | Bismuth titanite / Atomic observations / Domain walls / Polarization shift / Domain switching |
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| Outline of Annual Research Achievements |
Domain structures in BIT perovskite piezoelectrics were probed by PFM and TEM techniques. The TEM experimental results show that there mainly exist (110)-type 90 degree domain walls in the pure BIT ceramics. However, for the doped BIT ceramics, numerous (001)-type 180 degree domain walls appear on the lateral planes of grains. These domain walls were further examined by 3D PFM experiments, whose spatially visualized models were successfully established combined with the atomic observations of ion displacement and polarization shift via STEM. In addition, the polarization switching of BIT ceramics was initially investigated by a conductive PFM probe, which reveals the independent switching behaviors of polarization vector along a-axis and c-axis of unit cell.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The ceramic material used in this project was fabricated in advance through traditional solid-state reaction technique. Then, both of PFM- and TEM samples were also prepared as planned. Due to well-understanding the knowledge of PFM operation and TEM observation as well as nonlinear theory of phase transformation, the domain structures of BIT ceramics at multi-scale have been investigated successfully. Moreover, its polarization dynamics have been probed initially according to the PFM experiments. The current research findings have been published to the Journal of Scripta Materialia. As a whole, the research goals as planned have been achieved, and the research progress is partially in advance.
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| Strategy for Future Research Activity |
Previous research has revealed the domain structures in BIT ceramics in detail, and to some extent, has also initially probed its polarization dynamic behaviors under a small electric field via PFM. To further elaborate the polarization dynamics of the ceramic, the polarization switching will be investigated by macro poling engineering under a larger electric field, and the resulting domain configurations will be analyzed by the observations of SEM and PFM. Furthermore, the in-situ strain TEM sample will be prepared, and the stress-induced polarization dynamic behaviors and corresponding physical mechanisms will be expounded. From the 3D information of polarization switching, the spatial model of polarization dynamics under stress fields will be established.
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