2023 Fiscal Year Annual Research Report
Bismuth titanate-based high temperature piezoceramics: Domain structure and polarization dynamics
| Project/Area Number |
22KF0290
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| Allocation Type | Multi-year Fund |
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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, 工学研究院, 外国人特別研究員
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| Project Period (FY) |
2023-03-08 – 2024-03-31
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| Keywords | Bismuth titanate / Atomic arrangement / Domain walls / Piezoelectric responses / Spatial model |
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| Outline of Annual Research Achievements |
Bismuth titanate (BIT) ceramics are potential candidates for high-temperature sensing applications. Despite great advances in performance optimization, the research on domain structures and polarization dynamics are still scarce, limiting further development of such advanced functional materials for more emerging applications. Here, our work focuses on the detailed characterization of domain structures at multi-scale and polarization dynamic behaviors under both electrical and mechanical loads. In brief, the morphologies of domain structures were characterized by PFM at micro-scale, and then structural features of ferroelectric domains were analyzed by TEM and HRTEM at micro-scale and nano-scale, respectively. Most importantly, the polarization vectors of ferroelectric domains were directly observed by atomic-resolution HAADF-STEM. To elaborate the polarization dynamics under electric fields, a series of bias voltages were applied on the surface of ceramics by using PFM lithography, revealing the significant evolution behaviors of ferroelectric domains under applied electric fields. Besides, nanoindentation technique was employed to unravel the ferroelectric domain effect on mechanical properties of BIT ceramics, demonstrating that more domain walls have a positive effect on mechanical hardness. Moreover, polarization dynamics under both constant and cyclic mechanical stresses were elucidated based on nonlinear deformation or domain switching including reversible domain switching and irreversible domain switching in stress-strain curves of ceramics.
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