Research On The Preparation And Propeties Of PAN-PZT Based Ferroelectric Ceramics

Lead zirconate-titanate(PZT)-based piezoelectric ceramics have been widely used for varies of electronic devices because of their excellent dielectric,electromechanical coupling and piezoelectric properties. PZT-based binary ceramics systems are progressing toward to ternary and quaternary multi component systems in order to meet the ever-increasing demands of applications.One doping method is that introduction of new ferroelectric materials to PZT ceramic may obtain a new product which express mixed properties of the two ceramics. The other doping method is that being replaced by an equivalent, hard or soft doped to optimize the performance of ferroelectric materials. For example, when Fe3+replaced either Zr4+or Ti4+in PZT, the polarization hysteresis is significantly affected with the introduced of an internal bias field that tends to counteract the effects of external fields. Doped material is an ideal material for the fabrication of multilayer piezoelectric ceramic capacitors,precision micro-displacement, sensors, actuators, medical ultrasound transducers, and other functions of the device. In previous work, several PZT-based ternary solid solution have been investigated, such as Pb(Fe1/2Nb1/2)O3-Pb(Mg1/2Nb1/2)O3-Pb Zr0.52Ti0.48O3,Pb(Mn1/3Nb2/3)O3-Pb(Zn1/3N b2/3)O3-Pb Zr0.52Ti0.48O3,and Pb(Yb1/2Nb1/2)O3-Pb(Mn1/3Nb2/3)O3-Pb Zr0.48Ti0.52O3.Reports of investigations about Pb(Al1/2Nb1/2)O3-Pb Zr0.52Ti0.48O3(x PAN-PZT)are few, so in this work, the solid solutions of x PAN-PZT were designed and investigated.Therefore, the main work I did is that x PAN-PZT piezoelectric ceramics were well prepared and characterized and the component on the basis of further modification by doping has been also investigated. In this work, x PAN-PZT ceramics were prepared by the conventional mixed oxide method.The phase structure changes from the tetragonal to rhombohedra phase with increasing PAN mole fraction and the result suggested a morphtropic phase boundary(MPB) formed between the ferroelectric rhombohedra and tetragonal phases around x=0.1-0.12. The excellent electrical properties are obtained for ceramic with 0.1 mol%PAN, Stotal=0.34%, d33=365 p C/N, Pr=42 μC/cm2, TC=375 ℃.Then the effect of Sr2+doping for A site substitution to 0.1PAN-0.9PZT on phase compose, microstructure, piezoelectric properties and dielectric properties are systematically studied. The Curie temperature of the ceramic decreased significantly when doping with Sr2+, but there are few effects on the structure of Sr2+ doped PANPZT system and no phase transition was observed. The excellent dielectric, ferroelectric performance are obtained for the PAN-PZT ceramic with0.05 mol% Sr2+, d33=470 p C/N, Pr=32.5μC/cm2. When the amount of Sr2+replacement for 0.1 mol%, Stotal=0.34%, Spol=0.21%, but low Curie temperature,Tc=220 ℃.