Study On Processing And Properties Of High Power And Receiving-projecting Dual-purpose Piezoelectric Ceramic

In this paper, Lead Zirconate Titanate piezoelectric ceramics of Pb_0.94Sr_0.06(Zr_0.53Ti_0.47)O₃+0.1wt%(Ni₂O₃+Cr₂O₃) were prepared with conventional mixed solid oxide. In order to satisfy the requirements of high power devices, two series of Ce,Mn were doped in PZT dual system. The reaction temperature of piezoceramci powder during sintering was analyzed by DTA-TGA method. The effects of different influencing factors on the phase structure, microstructure, piezoelectric and dielectric properties were analyzed by means of XRD, SEM and electrical measurement.The experimental results indicate that the performance of PZT piezoelectric ceramics was improved by doping proper amount of CeO₂. Dopants and sintering temperature have little influences on phase, and only pure perovskite phase is observed in these patters peak. With increasing the Ce content, the phase transforms from tetragonal to rhombohedral. The proper amount of doping CeO₂ contributed to the growth of ceramic grain, and the grain is more uniform and compact. When doping much CeO₂, the doping CeO₂ will enrich at crystal boundary, which prevents grains from growing. With increase of sintering temperature, the grains grow up remarkably, however, too high sintering temperature is harmful to the grain growth because of the volatilization of PbO. When content of CeO₂ is 0.3wt% and the sintering temperature is 1280℃, the crystal shape of PZT piezoelectric ceramic is full, well-distributed and compacted. So, PZT ceramic has better piezoelectric property and lower dielectric loss. The property parameters of samples are: d₃₃=375pC/N, Kp=0.68, Qm=460,ε₃₃^T=1400, tanδ=0.0028.Piezoceramic with manganese addition has hard characteristic, but few manganese content can play the soft role. Mn dopant has great influence on phase, while sintering temperature has little influence on it. With increase of Mn content, the phase transforms from tetragonal to orthogonal obviously. When the content of MnO₂ is 0.05% and the sintering temperature is 1280℃, dielectric loss reduces and mechanical quality factor Qm increases, while the piezoelectric property increases little, the PZT ceramic has the best properties, that is, d₃₃=338pC/N, K_p=0.626, Q_m=421,ε₃₃^T=1260, tanδ=0.00384.When Ce and Mn ion were doped together, the phase structure of the ceramic is still perovskite structure. When 0.3 wt% CeO₂ was doped, along with the increase of MnO₂, perovskite structure of the sample gradually changed from the tetragonal phase to the tripartite phase. When th content of CeO₂ was 0.3wt % and the sintering temperature was 1280℃, proper amount of doping Mn can promote grain to grow up, but when doping too much would significantly inhibite the normal growth, existing some impurity in grain boundary. The influences of MnO₂ and CeO₂ composite dopant and sintered temperature on the PZT ceramics properties were studied by orthogonal tests. The results of orthogonal experiment show that Mn content is the key factor influencing its performance. With increase of Mn content, Kp, d₃₃ andε₃₃^T decrease, while Qm and tanδincrease. CeO₂ content is the important factor for the properties of PZT piezoceramic. With increasing, the admixture of CeO₂, K_p, d₃₃ andε₃₃^T will first decrease and then increase. When the doping amount exceeds 0.3 wt%, K_p, d₃₃ andε₃₃^T will have a reduced tendency again. The optimum conditions are W(MnO₂)= 0.05%, W(CeO₂)= 0.3%, and the sintering temperature is 1280℃, under which the properties are d₃₃=381pC/N,K_p=0.65,ε₃₃^T=1621,tanδ=0.0027,Q_m=485.