The Research On Pzn-plzt Piezoelectric Ceramics With High Properties

In morden times, piezoelectric ceramics has been widely used in aerospace, microelectronics and biological fields. With the development of modern technology, the performance requirements of piezoelectric ceramics have been being higher and higher. Through people's efforts for a long time, many kinds of high properties piezoelectric ceramics have been prepared. Among those systems, PZN-PZT becomes the focus because of its high piezoelectric performance, but the system has large dielectric loss and require higher conditions to prepare, such as hot-processing, which needs high cost, all of these limit its application in industry.By using precursor method and traditional solid reaction sintering method, we prepared PZN-PZT piezoelectric ceramics in the experiments, then through adding La2O3 into it and improving the production technology, we got PZN-PLZT piezoelectric ceramics with higher electric proformances. The piezoelectric constant can reach up to 550pC/N. At the condition of good electric properties, we reduced the dielectric loss to less than 2%, and enhanced the Curie temperature above 200℃in order to meet the requirements of industrial applications.The experiments mainly consist of two parts. One is research and preparation of pure PZN-PZT, the other is PZN-PLZT piezoelectric ceramics which consistans rare earth element La2O3 in it. First, in order to find the best temperature to synthesis precursor ZnNb2O6 and calcine the mixtures, the 0.2PZN-0.8PZT piezoelectric ceramics is prepared. Base on it, the best ratio of xPZN-1-xPZT piezoelectric ceramics is determined by changing the content of PZN. The other part is built base on the conclutions of the above experiments. We chose the best PZN-PZT stoichiometric and added element La2O3 into it to get higher properties. By studying the effects of La2O3 doping on microstructure and various electric properties, optical content of La2O3 is deterimined at last. At the same time we used different sintering temperatures to get the best properties.Through the experiments, we obtained the following conclutions:An appropriate proporition of La2O3 can improve the piezoelectric ceramics'electrical properties significantly, at the same time, improments of the technology, such as synthesis temperature of precursor ZnNb2O6 and sintering process, can improve the performance to some extent. But compared with La2O3 doping, it has lighter impacts.Through a variety of performace tests, we obtained the following performance parameters:d33=550pC/N; Kp=61.01%;ε33T/ε0=2394; tanδ=1.7%。Among them, d33 is piezoelectric constant, Kp is planar electromechanical coupling coefficient,ε33T/ε0 is relative permittivity under the free state.