Anisotropic dislocation-domain wall interactions in ferroelectrics

Area of Science:

• Materials Science
• Solid State Physics
• Ferroelectricity

Background:

• Dislocations typically degrade material properties.
• Controlling dislocation-domain wall interactions is crucial for functional materials.
• Barium titanate is a key ferroelectric material with potential for advanced applications.

Purpose of the Study:

• To develop a general framework for controlling dislocation-domain wall interactions in ferroics.
• To engineer anisotropic dielectric and electromechanical properties in barium titanate crystals.
• To investigate the impact of controlled dislocation networks versus point defects on material stability and functionality.

Main Methods:

• Fabrication of barium titanate crystals with an imprinted dislocation network.
• Characterization using transmission electron microscopy, X-ray diffraction, and nuclear magnetic resonance.
• Phase-field simulations and driving force calculations to understand defect interactions.

Main Results:

• Engineered anisotropic dielectric and electromechanical properties via controlled line-plane relationships.
• Achieved extraordinary and stable large-signal dielectric permittivity (≈23100) and piezoelectric coefficient (≈2470 pm V⁻¹).
• Demonstrated cyclic degradation in properties when using point-plane defect relations, contrasting with the stable network approach.

Conclusions:

• A 1D-2D defect approach provides a viable method for controlling ferroic properties.
• Engineered dislocation networks offer a pathway to enhance and stabilize material functionality.
• This framework is applicable for tailoring properties in a wide range of functional material systems.