The Study Of Fabrication And Performance Of Low Temperature Sintering Of Soft PZT-Based Piezoelectric Ceramics

Piezoelectric motor is a significant part in the various types of multilayer piezoelectricdevices, which has been extensive used in micro-electronics. In order to increase thedisplacement and decrease the response time of the piezoelectric motor, it is necessary forthe material to be a soft piezoelectric material with a low mechanical quality factor.However, to reduce the sintering temperature of a soft PZT piezoelectric ceramic is andifficulty nowadays. Therefore, to solve this problem, the Pb(Zn_1/3Nb_2/3)O₃-Pb（Zr,Ti）O₃（PZN-PZT） piezoelectric ceramic was selected as the research object. To reduce thesintering temperature and improve the properties of the ceramics, the preparing process ofceramic was improved, the basic formula was modified and metal oxide doping wasinvestigated.Firstly, the preparing process of piezoelectric ceramics was investigated. By modifyingthe calcination temperature of the raw materials, the piezoelectric properties improve. Byadjusting the ball milling process, the size of the powder after milling decreased from0.91μm to0.72μm. The powder with lower size was more active, so the piezoelectric andferroelectric properties of ceramics improved. Besides, the raw materials from differentmanufactures made great influence on the properties of material. Finally, with theimprovement of the preparing process of ceramic, the piezoelectric properties increased, thepiezoelectric constant d₃₃increased from340pC/N to527pC/N, and the electromechanicalcoupling coefficient improved from0.31to0.37.Based on the adjusting of the preparing processes of ceramic, the effects of basicformula on the properties of material were studied. The concentration of Pb(Zn_1/3Nb_2/3)O₃in the PZN-PZT ceramics was changed, and the optimized properties were obtained whenthe formula was0.3Pb(Zn_1/3Nb_2/3)O₃-0.7Pb（Zr,Ti）O₃. The ratio of Zr/Ti was studied, andwhen the ratio of Zr/Ti was49/51, the system lied on the morphotropic phase boundary.Finally, the concentration of Pb element was investigated. When the concentration Pbelement was equal the stoichiometric ratio, the best properties of ceramics were obtained.The effects of Li₂CO₃and Sm₂O₃on the properties of ceramics were studied. With the addition of Li₂CO₃, the sintering temperature of ceramics reduced from1125℃to950℃and the piezoelectric properties did not deteriorate. However, when the sinteringtemperature was below950℃, the piezoelectric properties decreased obviously with theLi₂CO₃addition. The additive of Sm₂O₃could improve the piezoelectric properties whenthe samples were sintered at900℃. Finally, when sintered at900℃the optimizedproperties of ceramics were obtained as d₃₃=483pC/N，k₃₁=0.376，Qm=73.09，εr=2524，tanδ=0.0178。...