Characteristics of Li x (K y Na 1-y ) 1- x (Nb 0.9 Ta 0.06 Sb 0.04 )O 3 Lead-Free Piezoelectric Ceramics Ming-Chang Kuan Department of Electronic Engineering, Southern Taiwan University

OUTLINE Introduction Introduction Experimental Procedures Experimental Procedures Results and Discussion Results and Discussion Conclusion Conclusion

Introduction Applications of Piezoelectric Ceramics ArmySonars IndustryCivil Buzzer 、 Sensors 、 Actuators 、 Transducers 、 Cleaner 、 Transformer 、 SAW Medical Extracorporeal Shockwave 、 Cosmetology 、 Examination

Piezoelectric Ceramic’s Vibration Modality and Range

Market PZT Piezoelectric Materials

Lead-Free Piezoelectric Ceramics BaTiO 3 -based Materials BaTiO 3 -based Materials (Bi 1/2 Na 1/2 )TiO 3 -based Materials (Bi 1/2 Na 1/2 )TiO 3 -based Materials Bi-layered Structure Materials Bi-layered Structure Materials (KNaNb)O 3 -based (KNN-based) Materials (KNaNb)O 3 -based (KNN-based) Materials Tungsten bronzes structure Tungsten bronzes structure

The Dopants of Piezoelectric Ceramics The Dopants of Piezoelectric Ceramics PerformanceElements K p Increasing Li‚Ag‚Sb‚Ta‚Sn Q m Increasing Cu‚Mn,Sn Sintering Ability Li‚Cu‚Sn‚Sb

Experimental Procedures K 2 CO 3, Na 2 CO 3, Li 2 CO 3, Sb 2 CO 3, Nb 2 CO 3, Ta 2 CO 3, Nb 2 CO 3, Ta 2 CO 3 Mixed & Ball-milled (10 hr) Calcined (89 0  C/6 hr) Ball-milled 6 hr PVA (5 wt %) pressed into pellets Sintering in the air (1060~1100  C /4hr) Ag/Pd electrodes Polarized in 100  C silicon oil (4kV/mm / 30 min) Measured (HP 4294A ) (kp‚  r ‚ tanδ)

The coefficients and are depend on the resonant modes of the radial circular plate resonators

XRD patterns for x=0.06 and y=0.5 Results and Discussion

SEM Microstructures for x=0.06 and y= °C 1060 °C 1080 °C1090 °C

XRD patterns for x=0.06 and sintering temperature=1090  C

SEM Microstructures for x=0.06 and sintering temperature=1090  C y=0.47y=0.485 y=0.495y=0.5

Electromechanical coupling factors for y=0.48

Relative dielectric constants for y=0.485

Loss tangent for y=0.485

Electromechanical coupling factors for x=0.06

Relative dielectric constants for x=0.06

Loss tangent for x=0.06

Electromechanical coupling factors for x=0.06 and y=0.485

Relative dielectric constants for x=0.06 and y=0.485 (1 kHz)

Conclusion The amounts of A-side atoms (Li, K, and Na) will cause to the lattice distortion and lead to the improvements of piezoelectric and dielectric characteristics The amounts of A-side atoms (Li, K, and Na) will cause to the lattice distortion and lead to the improvements of piezoelectric and dielectric characteristics The best sintering temperature is 1090  C The best sintering temperature is 1090  C The best composition is obtained from x=0.06 and y=0.485, The best composition is obtained from x=0.06 and y=0.485, The optimum characteristics are: k P =42.8 %,  r =1280, tan δ =3, and T c =340  C The optimum characteristics are: k P =42.8 %,  r =1280, tan δ =3, and T c =340  C

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