Research And Preparation On The Low Temperature Sintering Of PZT-based Piezoelectric Ceramics

It is well known that PZT-based piezoelectric ceramics have been an important station in the piezoelectric ceramics field because of their stable function, excellent electric properties, available production and low cost. But their high sinter temperature make lead oxide lossed very serious in sintering process, which result in deflecting stoichiometric proportion, deteriorating the electric properties and polluting the environment. So it is an active and effectual method in reducing the loss of lead oxide that use the technology of the low temperature sintering. Also, the argentine and copper can be used as the electrode for greatly decreasing the cost of once-firing by the low temperature sintering. Therefore, the studies of the low temperature sintering have lots of economic and social benefits.The samples were prepared by solid-state reaction method, and the doping and modification and the low temperature sintering of PZT-based piezoelectric ceramics were studied by the liquid-phase sintering. At last the new compounding PCN-PFW-PZT piezoelectric ceramic was prepared, that had good properties and lower sintering temperature.Firstly, single oxide WO₃ and CuO were additioned respectively to the PMS-PNN-PZT piezoelectric ceramics, and the effects on microstructure, electric properties and sintering function were studied. The results showed that the addition of WO₃ exhibition the softness doping. The samples could be sintered at 1100℃with WO₃ doped and electric properties having a little drop. The addition of CuO could make samples sintered at rough 1000℃, but the electric properties had bad decline. By the view of microstructures, they both show the character of the liquid sintering.By the studies of single oxide doping, the next step, the perovskite structure of solid solution Pb(Fe_2/3W_1/3)O₃ (PFW) and Pb(Cu_1/3Nb_2/3)₃ (PCN) that contain above two oxides respectively were used to co-doping for the low temperature sintering and good electric properties. The effects of PFW's contents in PFW-PZT piezoelectric ceramics were studied. It was found that the addition of PFW could improve PZT piezoelectric ceramics'sintering temperature and worsened electric properties a little. When the contents of PFW was 4.5 mol%, the best sintering temperature was 1100℃, and here the electric properties were the best comparatively.In order to low the sintering temperature, the effects of PCN's contents in PCN-PFW-PZT piezoelectric ceramics were studied. The results revealed that the addition of PCN could reduce the sintering temperature to 1000℃, and the system held good electric properties. The mechanism may be the co-action of softness and hardness doping. The finally compound 0.08PCN-0.045PFW-PZT was fixed, and when sintered at 1000℃, its optimized electric properties were d₃₃=381 pC/N,K_p=0.58,Q_m=1025,ε_r=1323,tgδ=0.015. This compound can reduce the evaporation of PbO, and also its sintering temperature match the qualification of the temperature of rich-argentums material pole.