Bismuth titanate-based high temperature piezoceramics: Domain structure and polarization dynamics

2021 Fiscal Year Annual Research Report

• Project/Area Number: 21F21704
• Allocation Type: Single-year Grants
• Research Institution: Kyushu University
• Principal Investigator: 陳 強 九州大学, 工学研究院, 教授 (30264451)
• 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
• Project Period (FY): 2021-11-18 – 2024-03-31
• Keywords: Bismuth titanate / Atomic arrangement / Domain walls / Piezoelectric responses / Spatial model

Outline of Annual Research Achievements

The atomic-scale microstructural feature of bismuth titanate high temperature ceramics was investigated, directly revealing the atomic arrangement in layered perovskite structure of Aurivillius phase. Subsequently, we initially probed the domain structures in bismuth titanate piezoceramics. The transmission electron microscopy (TEM) experimental results show that there mainly exist (110)-type 90 degree domain walls in bismuth titanate ceramics. These domain walls were further examined by three dimensional piezoresponse force microscopy (3D PFM) experiments. Finally, a spatially visualized model of (110)-type 90 degree domain walls was established according to the specific piezoelectric responses of ferroelectric variants under multiple 3D PFM modes.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The PFM- and TEM samples were well prepared as planned. Due to well-understanding the knowledge of PFM operation and TEM observation, the crystal structure and domain structure of bismuth titanate high temperature ceramics have been investigated initially. The research findings are summarizing and preparing for writing a paper to submit it to an international journal. As a whole, the research goals as planned have been achieved, and the research progress is partially in advance.

Strategy for Future Research Activity

Previous research, to some extent, has revealed general domain structure in pure bismuth titanate high temperature ceramics by PFM probing and TEM observation. To further elaborate the domain structure of the ceramic, we will investigate ferroelectric domain and ion displacement at atomic-scale by using high resolution TEM and scanning TEM combined with two dimensional Gaussian Fitting technique. In addition, the polarization switching of bismuth titanate high temperature ceramics will also be investigated by micro-poling engineering under an external electric field and a conductive PFM probe, respectively, to initially unravel the polarization switching mechanism and attempt to establish the spatial model of polarization dynamics.