The Investigation Of Preparation And Doping Modification Of Pb_0.96La_0.04(Zr_0.55Ti_0.45)O₃Piezoelectric Ceramics

The Pb1-yLay (ZrxTi1-x)1-y/4O3(PLZT)piezoe lee trie ceramics doped by Sb2O3were prepared by conventional solid solution method. The X-ray diffraction(XRD) were applied to analyze phases of the sintered ceramics, and the scanning electronic microscope (SEM) were applied to analyze micro structure of ceramics. The effects of the composition,packing powders,sintering time the sintering temperature on the dielectric and piezoelectric properties of the system were also discussed. Through the experiments,we obtained the following conclutions:an appropriate proporition of Sb2O3can enhance the dielectric and piezoelectric properties of the PLZT ceramics significantly. At the same time,improvements of the techno logy, such as calcining temperature and sintering technology,can improve the dielectric and piezoelectric properties to some extend,especially calcining temperature and sintering time. The lack of lead which leads to many lead vacancies existing mainly depended on the packing powders.If the packing powders were not suitable, the properties of materials would be worse.When the Zr/Ti=55/45with adding4.0at.%La3+and1.5wt.%Sb3+the ceramics which were calcined at975℃and sintered at1280℃obtained the best properties:d33=683pC/N,Kp=0.673,ε33T=3426,tgδ=1.80%,Tc=238℃.The best formula: Pb0.96La0.04(Zr0.55Ti0.45)0.9903+1.5wt.%Sb2O3.(Shortened form in the following dicuss: PLSZT). The results of this study would play an importrent part in the manufacture process.In addition, the micro structure and the electric properties of the PLSZT system doped by Sr2+close to the morphotropic phase boundary (MPB) were investigated systematically as a function of the Zr/Ti ratio and the content of Sr2+doping. The effect of the Sr is to move the morphotropic boundary somewhat toward the rhombohedral phase side and, in addition, there is a decrease in the distortion from cubic symmetry. The greatest properties were obtained with Zr/Ti=55.5/44.5.And in general,the substitution of Sr in Pb site made the grains grow well with clear boundaries and gave improved dielectric constanteand increased piezoelectric strain coefficient d33,with slight decrease in the Curie temperature.From what has been discussed above,we can get the best formula of the ceramics with Sr2+doping: Pb0.96La0.04(Zr0.555Ti0.445)0.99+1.5wt%Sb2O3+1.0at%SrCO3.The main parameters:d33= 736pC/N,Kp=0.68,ε33T=3282,tgδ=2.0%,Tc=220℃,Pr=34.49μC/cm2,Ec=9.28KV/cm The piezoelectric strain coefficient d33of the ceramic went up,which increased the working range of the piezoelectric ceramics.