Investigations On The High Power Piezoelectric Ceramics And Multilayer Structure Prepared By Tape Casting Method

Compared with the traditional electromagnetic motor, piezoelectric ultrasonic motor has outstanding advantages in many areas. The suitable materials of piezoelectric motor should be high power piezoelectric ceramics, of which the piezoelectric coefficients d33should be higher than300pC/N, electromechanical coupling factor kp should be higher than0.5, mechanical quality factor Qm should be higher than1000, dielectric loss constant tand should be lower than0.5%. In this paper,0.09Pb(Sn1/3Nb2/3)O3-0.09Pb(Zn1/3Nb2/3)O3-xPbZrO3-(0.82-x)PbTiO3(PSN-PZN-xPZ-PT) ceramics were prepared by conventional solid-state reaction method. The effects of different Zr/Ti ratios from39/43to44/38on the piezoelectric properties of PSN-PZN-xPZ-PT ceramics were investigated. Combining with the XRD patterns, the Morphotropic phase boundary (MPB) was locked near x=0.41. Finally, when calcining temperature was880℃and sintering temperature was1200℃,the optimized properties of PSN-PZN-0.41PZ-PT ceramics were obtained as d33=388pC/N、=0.58、 ε33T/ε0=1480、Qm=80.To obtain hard type piezoelectric ceramic, MnO2was selected as a dopant. The effects of different concentrations of Mn on the structure, dielectric and piezoelectric properties of the PSN-PZN-0.41PZ-PT were investigated. The piezoelectric coefficients, the electromechanical coupling factor, relative permittivity, mechanical quality factor, Curie temperature, remnant polarization, coercive field of PSN-PZN-0.41PZ-PT ceramics with1.5mol%Mn were320pC/N、0.55、1350、1350.0.45%、313℃,18.8μC/cm、20kv/cm. The vibration velocity of the ceramics was68mm/s at resonance frequency of90kHz under100Vpp voltage drive, which was17%higher than traditional materials PZT-4.The tape-casting process was studied in this paper. The organic additives included solvent, binder and plasticizer. Based on the characteristic of powder, butyl acetate was chosen as solvent, polyvinyl butyral (PVB) was chosen as binder and Di-n-octylo phthalate was chosen as plasticizer. The experiments of preparing piezoelectric ceramic green tape using tape-casting technique had been done. The best ratio of power, solvent, binder and plasticizer was55:35:5:5. Comparing with dry pressure method, the tape casting method showed superiority. XRD patterns showed that samples had the structure of perovskite. The thick film prepared by tape casting could be Co-fired with the inner electrode. This can be used for multilayer structure ceramics.