High-Performance Lead-Free Ceramics With Simultaneously High Piezoelectricity and High Mechanical Quality Factor

Area of Science:

• Materials Science
• Solid State Physics
• Ceramics Engineering

Background:

• High piezoelectric coefficient (d33) and mechanical quality factor (Qm) are crucial for high-power piezoelectric applications.
• A trade-off typically exists between high d33 and high Qm in lead-free piezoelectrics due to mobile domain walls increasing losses.
• Existing lead-free materials struggle to meet the demanding performance requirements for advanced applications.

Purpose of the Study:

• To overcome the inherent trade-off between high d33 and high Qm in lead-free piezoelectric materials.
• To investigate the effect of defect dipoles on the piezoelectric properties of lead-free barium titanate systems.
• To develop novel lead-free piezoelectric ceramics with enhanced performance for high-power applications.

Main Methods:

• Synthesis of Mn-doped Ba(Sn, Ti)O3 ceramics at the quadruple point (QP) composition.
• Characterization of piezoelectric properties, including d33 and Qm.
• High-resolution scanning transmission electron microscopy (HR-STEM) for microstructural analysis.
• Phase-field simulations to understand the underlying mechanisms.

Main Results:

• Mn doping in Ba(Sn, Ti)O3 ceramics successfully introduced defect dipoles, mitigating the d33-Qm trade-off.
• 0.5%Mn-doped BST exhibited a d33 of 710 pC/N and Qm of 929; 1%Mn-doped BST showed a d33 of 614 pC/N and Qm of 1138.
• Achieved a 1.6-fold increase in d33 and a 10-fold increase in Qm for BST-0.5%Mn compared to undoped BST.
• Microstructural analysis and simulations revealed that coexisting QP phases with symmetry-conforming defect dipoles are responsible for the enhanced properties.

Conclusions:

• The study demonstrates a novel approach to simultaneously enhance d33 and Qm in lead-free piezoelectric materials by introducing defect dipoles.
• The findings challenge the conventional understanding of the physical incompatibility between high d33 and high Qm.
• This work provides a pathway for designing eco-friendly, high-performance piezoelectric materials for sustainable and efficient high-power applications.