Studies On Piezoelectric Properties Of PLZT-based Ferroelectric Ceramics

Piezoelectric materials,which can realize the conversion between mechanical energy and electrical energy,are widely used in sensors,actuator,ultrasonic transducers etc.With the development of technology,the requirements for piezoelectric properties of materials are getting harder,so there is an urgent need for materials with strong piezoelectricity.In this paper,Pb1-xLax（ZryTi1-y）1-x/4O₃+1 wt%Sb₂O₅（PLZT,x=0.055～0.090,y=0.55～0.64）ceramics were synthesized by solid state reaction method.By XRD test,it is indicated that tetragonal phase content decreases and rhombohedral phase content increases with the increase of Zr content For high La content,there is a point of discontinuity with the increase of Zr content.However,the solid solubility of Sb₂O₅ in samples with high La content and high Zr/Ti ratio decreases,and pyrochlore phase will appear.The excellent piezoelectric performance is obtained at x=0.060,y=0.58（d33=880 pC/N,kp=0.7,Qm=49,εr=5200,tanδ=0.019）.Combined with the XRD test results,the local phase diagram of the system was drawn based on d33.According to the dielectric temperature spectrum,the samples possess relaxor characteristicTaking Pb_0.94)La_0.06(Zr_0.58Ti_0.42)_0.98O₃ as the object,the effect of Sb3+ion occupation on performance was explored by the design of different formulas.Dielectric,piezoelectric,dielectric properties and XRD were tested at room temperature,the results suggested that Sb3+ion designed into the B site in the perovskite structure can obtain great piezoelectricity.Taking Pb_0.935La_0.065(Zr_{0.59Ti0.410.98375}O₃+1 wt%Sb₂O₅+x wt%Pb(Yb_0.5Nb_0.5)O₃（PYN）as the objec When x=1.0,the optimal piezoelectric performance is obtained:d33=930 pC/N,kp=0.67,Qm=42,εr=6000,tanδ=0.028.The source of strong piezoelectricity is that the addition of PYN changed the phase structure of PLZT 6.5/59/4 from coexistence of tetragonal phase and pseudocubic phase to pseudocubic phase.At last,comparing the performance,dependence of electrical properties on temperature,and the change of XRD diffraction peaks before and after poling between Pb_0.935La_0.065(Zr_0.59Ti_0.410.98375)O₃+1 wt%Sb₂O₅+1 wt%PYN（1PYN-PLZT）and Pb_0.9625Sm_0.025[（Mg1/3Nb2/3）_0.69Ti_0.31]O₃（2.5Sm-PMN-3 1PT）.It was found that the movement of domain wall has a significant contribution to the piezoelectric dielectric properties in the weak field as to 2.5Sm-PMN-31PT,while the main contribution of the 1PYN-PLZT piezoelectric and dielectric properties comes from the intrinsic effect.Comparing with 2.5Sm-PMN-31PT,1 PYN-PLZT has higher polarization and coercer field,as well as higher dielectric peak temperature and depolarization temperature.