Textured Lead-Free Ceramic with High Thermal Stability and Electrical Quality Factor

Area of Science:

• Materials Science
• Solid State Chemistry
• Ceramics Engineering

Background:

• Maintaining high piezoelectric figures of merit (FOM) in (K,Na)NbO3 ceramics across varying temperatures and electric fields is a significant challenge.
• Piezoelectric materials are crucial for sensors, actuators, and energy harvesting devices, necessitating robust performance under diverse conditions.

Purpose of the Study:

• To develop a textured (K,Na)NbO3-based ceramic with improved piezoelectric properties, thermal stability, and fatigue resistance.
• To investigate the effects of texturing and MnO2 doping on the electromechanical performance and energy harvesting capabilities of the material.

Main Methods:

• Fabrication of a textured K0.48Bi0.02Na0.5Nb0.92Sb0.04Zr0.04O3 ceramic using NaNbO3 templates.
• Optimization of microstructural orientation and MnO2 doping (0.1 mol%) to enhance electrical quality factor (Qe).
• Characterization of piezoelectric coefficients (d33, k31), strain response, P-E and S-E loops, and energy harvesting performance under various conditions.

Main Results:

• Achieved a high texture degree of ~98% with piezoelectric coefficients d33 = 570 pC/N and k31 = 0.4 at room temperature.
• Improved electrical quality factor (Qe) from 22 to 33 through MnO2 doping.
• Demonstrated excellent fatigue resistance up to 10^6 cycles and a maximum output power of ~50 µW for energy harvesting.

Conclusions:

• The combination of defect engineering (Mn doping) and microstructural engineering (texturing) significantly enhances the electromechanical properties of (K,Na)NbO3 ceramics.
• The developed material exhibits a promising balance of high piezoelectric performance, thermal stability, and fatigue resistance, suitable for practical energy harvesting applications.