Research On The Properties Of The PZT Piezoelectric Ceramics Doped With Antimony And Lithium And The Optimization Of Process

The Sb2O3 doped dual piezoelectric ceramics was choosed as reseach object in this article, and the specimens were prepared by conventional solid solution method. The best proportion of PSZT ceramics sysyem, the different adding method of Sb2O3 doped PZT, the influence of different electrodes and metallized temperature in PSZT ceramics and the Li₂CO₃ doped PSZT ceramics were studied.As to the PSZT ceramics, when the ratio of Zr/Ti is 52:48 with adding 1.2wt.% Sb2O3 which was sintered at 1200℃, the best properties of specimens were obtained:ρ=7.79g/cm3,ε₃₃^Tε0=1992, tanδ=1.78%, d33 = 410pC/N, Kp = 0.65, Tc=385℃, Td≈270℃. At this time, grains grew well with clear boundaries, and the average size of grains was 2μm. But with the ingcreasing of Sb2O3, the grain size decreased gradually.There was no change in the perovskite stucture of PSZT ceramics with different adding method. By comparison, the method of plus is superior to the mentod of replacement. For the former, the grain distribution is uniformity with high density; for the later, the grain size was different, as a result, the density declined largely. The performance decline of the latter is mainly due to the lack of lead which leads to many lead vacancies existing, thereby worsening the properties of materials.For the PSZT piezoelectric ceramics coated with different electrodes which were metallized at differnet temperature, the silver-palladium electrode was better than silver electrode. And the properties of specimens appeared first increased and then decreased tendency where the optimun value was obtained at 800℃.At this temperature, microscopic morphology analysis indicated that the particles of silver electrode combined compactly, thus there were independent holes. However, the particles of silver-palladium electrode interweaved mesh structure which was favorable to strengthen the strength and stability of electrode layer. The line scanning showed that the Ag in electrodes diffused to ceramic substrates gradually, that is to say transition layer was formed. The spread of Ag of silver electrode was more serious than silver-palladium electrode, which was bad for piezoelectric properties. The specimens properties coated with silver-palladium electrode was better than coated silver electrode.The reasons were as follows: on one hand, the formation of mesh structure; on the other hand, the silver-palladium alloy formed because of the addition of Pd, which inhabited the diffusion of silver ions to ceramic matrix. As to the Li2CO3 doped PSZT ceramics, the effect of doping quantity, synthesis temperature and sintering temperature on PSZT ceramics were studied respectively. The results showed that the sintering temperature reduced by 30℃⁵0℃with the addition of Li2CO3. When the content of Li2CO3 was 0.05wt.%, synthesized at 900℃and sintered at 1170℃, the comprehensive performances of samples were obtained:ρ=7.78g/cm³,ε₃₃^Tε0=1803, tanδ=1.65%, d33=387pC/N, kp=0.64, Tc=415℃, Td≈300℃. The higher curie temperature and depolarization temperature improved the application temperature of piezoelectric ceramics further.