Study On The Preparation And Properties Of PZN-PZT-Based Piezoelectric Ceramics

Pb(Zr,Ti)Cb (PZT) systems, which exhibit excellent piezoelectirc andelectromechanical performances, play a significant role in electronic industry,mainly in the manufacture of actuators and sensor devices. PZT was found to hostextraordinarily excellent properties for compositions close to the morphotropicphase boundary(MPB), which was located around PbZr03:PbTi03~0.52:0.48.Inorder to further improve the performance of PZT to satisfy specific applications,two effective way have been proposed. One way is to enhance the dielectric andpiezoelectric properties of PZT by using dopants. Another effective way is toform a ternary system with the addition of lead-based relaxor ferroelectrics toPZT. Among all the lead-based relaxor ferroelectrics, lead zinc niobatePb(Zni/3Nb2/3)03(PZN) is one of the most important relaxor ferroelectrics.In previous work，several PZT-based ternary solid solution have beeninvestigated, such as Pb(Fei/2Nbi/2)03-Pb(Mgi/2Nbi/2)03-PbZroi.52To.4s03,Pb(Mni/3Nb2/3)03-Pb(Zni/3Nb2/3)03-PbZro.52Tiod Pb.4803, an(Ybi/2Nbw2)Ch-Pb(Mm/3Nb2/3)03-PbZro.48Tio0date.523. To, there have been no reports ofinvestigations into Pb(Al i/2Nbi/2)03-Pb(Zni/3Nb2/3)03-PbZro.52Tio0N.483(xPA-PZT-PZN), so in this work，the solid solutions of PZT-PZN-xPAN were designedand investigated. In this work, xPZN-PZT ceramics were prepared by a conventional method. Through investigating xPZN-PZT ceramics, some conclusions can be found: Further increasing the PAN content, the phase structure changes from the tetragonal to rhombohedral phase, the result suggested a morphtropic phase boundary (MPB) formed between the ferroelectric rhombohedral and tetragonal phases around x=0.2-0.3; near the MPB region, the optimum electric properties of Stotal=0.47%, d33=423pC/N, and the d33=570pC/N. And the optimal formula was determined as0.2PZN-0.8PZT.Based on the optimal formula, ternary solid solution xPAN-(0.2-x)-PZN-0.8PZT was designed and fabricated. The composition, temperature, and frequency dependence of the dielectric, ferroelectric, and piezoelectric properties were systematically studied. The main works in this dissertation are as follows: Combined with the XRD analysis and the room temperature electric properties, a MPB should be identified to be in the range of0.02<x<0.05; With the introduction of PAN, The optimum electric properties of Pm=46.3μC/cm2, Pr=42μC/cm2, Pr/Pm=90.5%, Tm=283℃, Stotal=0.48%, Sneg=0.31%, and d33=410pC/N were achieved in PZT-PZN-xPAN ceramics with x=0.02, indicating an excellent ferroelectric property; Increasing PAN content tends to increase the unipolar strain of PZT-PZN-xPAN ceramics, and a large strain response of-0.24%with normalized strain Smax/Emax as high as767pm/V was obtained for the PZT-PZN-0.1PAN under a low electric field of～3kV/mm at room-temperature. The experimental results demonstrate that this system could be an ideal piezoelectric material in the manufacture of actuators and sensor devices.