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Optimizing electro-strain via manipulating the oxygen octahedral structure in BF-BT-based ceramics
Bing Li1, Junfei Guo1, Shizhao Zhong1
1Department of Materials Science, Sichuan University, 610064, Chengdu, China. wujiagang0208@163.com.
Physical Chemistry Chemical Physics : PCCP
|December 5, 2022
Summary
Doping bismuth ferrite-barium titanate (BF-BT) ceramics with NaNbO3 enhances electro-strain by optimizing oxygen octahedron symmetry and tilt. This structural tuning, particularly with Na+, leads to improved electrical properties in BF-BT ceramics.
Area of Science:
- Materials Science
- Solid State Physics
- Ceramic Engineering
Background:
- Electrical properties of bismuth ferrite-barium titanate (BF-BT) ceramics are significantly influenced by doping.
- The role of intrinsic structural factors, such as oxygen octahedron symmetry and tilt, in BF-BT's electro-strain remains poorly understood.
- Existing research primarily focuses on doping effects, neglecting fundamental structural contributions to electro-strain.
Purpose of the Study:
- To investigate the correlation between intrinsic crystal structure evolution and electro-strain in BF-BT ceramics.
- To elucidate the mechanism by which dopant ionic radii influence structural symmetry and electro-strain.
- To identify optimal doping strategies for enhancing the electro-strain of BF-BT ceramics.
Main Methods:
- Designed three doping systems: BF-BT-xLiNbO3, BF-BT-xNaNbO3, and BF-BT-xKNbO3, utilizing dopants with similar chemical properties but varying ionic radii (Li+, Na+, K+).
- Performed macro-property characterization to measure electro-strain.
- Conducted microscopic crystal structure analysis and real-space domain imaging to examine structural changes and domain configurations.
Main Results:
- The BF-BT-xNaNbO3 system exhibited the largest electro-strain (S ~ 0.25%) at x = 0.02.
- Na+ doping enhanced the symmetry of O-O and Fe-O bond lengths while maintaining optimal oxygen octahedron tilt.
- Li+ and K+ doping induced asymmetry in bond lengths, negatively impacting electro-strain; improved strain correlated with miniaturized maze-like domain structures.
Conclusions:
- Synergistic effects of bond length symmetry, appropriate oxygen octahedron tilt, and miniaturized domain structures are responsible for enhanced electro-strain in BF-BT-0.02NaNbO3.
- Understanding the impact of intrinsic crystal structure on electro-strain is crucial for tailoring BF-BT electrical properties.
- NaNbO3 doping presents a promising route for optimizing the electro-strain performance of BF-BT ceramics.
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