【作者】 万丹丹；

【导师】 杨颖；

【作者基本信息】 南京航空航天大学 ， 材料学， 2010， 硕士

【摘要】 近年来,由于压电作动器和变压器的大规模使用,大功率压电陶瓷材料引起了广泛的研究和关注。为获得高的功率密度,多层叠片式压电陶瓷元器件也逐渐成为近期的研究热点。日前实现叠层结构更倾向采用Ag-Pd贵金属作内电极多层叠合一次烧成。若PZT压电陶瓷能在900°C以下烧成,则可采用Ag作内电极,这样不仅可以降低成本也可以抑制PbO的挥发。目前,人们通过添加钙钛矿型弛豫铁电体发展了许多三元系、四元系的PZT基大功率压电陶瓷。PZT–PMS–PZN由于具备优异的电学性能:d₃₃ = 369 pC/N, Qm = 1381, k_p = 64%, tanδ= 0.44%,ε₃₃^T = 1600,而被认为是大功率的候选材料之一。然而针对该材料的研究局限于熔盐合成法,且烧结温度偏高。为此,本课题选择PZT–PMS–PZN材料为研究对象,从成分设计、低温烧结特性、掺杂改性对材料的显微结构与电学性能的影响进行系统的研究。采用普通固相法制备四元系0.90Pb(Zr_xTi_1-x)O3-0.05Pb（Mn1/3Sb2/3）O3-0.05Pb（Zn1/3Nb2/3）O3陶瓷,进一步添加CuO烧结助剂降低烧结温度。研究不同Zr:Ti比和CuO添加量对陶瓷微结构、电学性能的影响规律。结果表明,Zr:Ti比对陶瓷电学性能影响显著,当Zr:Ti=48:52时,1100°C烧结后的陶瓷具有优异的电学性能:d₃₃ = 355 pC/N, Qm = 1550, k_p = 60%, tanδ= 0.33%,ε₃₃^T = 1308。该配方在添加1.0 wt% CuO后,烧结温度下降到900°C,并且保持较好的电学性能:d₃₃ = 306 pC/N, Qm = 997, k_p = 53.6%, tanδ= 0.50%,ε₃₃^T = 1351。通过对0.90PZT-0.05PMS-0.05PZN + 1.0 wt% CuO陶瓷原始粉体进行了差热-热失重分析,930°C左右出现的吸热峰证实了烧结过程中液相的存在。为进一步优化0.90PZT-0.05PMS-0.05PZN + 1.0 wt% CuO陶瓷的压电性能,选择La₂O₃和Nb₂O₅分别作为A-/B-位的施主掺杂物。研究结果表明,La₂O₃掺杂可以显著提高d₃₃和k_p值,且几乎不降低Qm。当掺杂0.5 wt% La₂O₃时,陶瓷的电学性能最佳:d₃₃ = 355 pC/N, Qm = 936, k_p = 58.4%, tanδ= 0.32%,ε₃₃^T= 1590。另一方面,Nb₂O₅掺杂对陶瓷压电性能的影响相对复杂,当Nb₂O₅掺杂量为0.5 wt%时,陶瓷也具有良好的电学性能:d₃₃ = 300 pC/N, Qm = 971, k_p = 58.4%, tanδ= 0.36%,ε₃₃^T = 1332.。更多还原

【Abstract】 Nowadays, high-power piezoelectric ceramics have received extensive attention and study due to their increasing applications in piezoelectric actuators and transformers. Particularly, the multilayer layer piezoelectric devices become a popular topic for their high power density. In general, co-firing process is preferred for multilayer devices. If the piezoelectric ceramics could be sintered below 900°C, pure Ag internal electrodes can be used instead of Ag-Pd alloy and the volatilization of PbO can be suppressed as well.These days, some ternary or quaternary high-power piezoelectric ceramics were obtained by adding perovskite structure relaxors into PZT system. Among them, PZT–PMS–PZN quaternary system is a most qualified candidate for high-power applications with good electrical properties: d33 = 369 pC/N, Qm = 1381, k_p = 64%, tanδ= 0.44%, andε₃₃^T = 1600. However, previous studies used the molten salt synthesis method and the sintering temperature was as high as 1100°C. Therefore, PZT-PMS-PZN quaternary system was selected in this study, the composition design, low temperature sintering behavior and doping effects were discussed with respect to the crystal structure, micro-morphology and electrical performance.0.90Pb(Zr_xTi_1-xO3-0.05Pb(Mn1/3Sb2/3O3-0.05Pb(Zn1/3Nb2/3)O3 quaternary high power piezoelectric ceramics were synthesized by using conventional solid-state sintering; to decrease the sintering temperature CuO was added as a sintering agent. The crystal structure, micro-morphology and electrical properties were studied in terms of Zr:Ti ratio and CuO content. These results indicate that the Zr:Ti ratio has a significant influence on the electrical properties; 0.90PZT-0.05PMS-0.05PZN （Zr:Ti=48:52） ceramics sintered at 1100°C with maximum tetragonality exhibit the optimal electrical properties: d33 = 355 pC/N, Qm = 1550, kp = 60%, tanδ= 0.33%, andε33^T = 1308. Moreover, 1.0 wt% CuO additive has a significant improvement in the sinterability of 0.90PZT-0.05PMS-0.05PZN ceramics, lowering the sintering temperature to 900°C and maintaining moderate electrical properties: d33 = 306 pC/N, Qm = 997, kp = 53.6%, tanδ= 0.50%, andε33^T = 1351. The low temperature sintering behavior could be explained with the formation of a transient liquid phase by CuO during sintering. Moreover, the endothermic peak at about 930°C in the differential thermal analysis （DTA） curve of the raw ceramic powder provides further evidence for amorphous phase.To obtain more optimum piezoelectric properties, La2O3 and Nb2O5 were selected as donor doping to 0.90PZT-0.05PMS-0.05PZN + 1.0 wt% CuO system. Our study demonstrates that La2O3 is very effective on piezoelectric properties, remarkably increasing the d33 and kp value without degrading the Qm value. Finally, 0.5 wt% La2O3 added 0.90PZT-0.05PMS-0.05PZN + 1.0 wt% CuO ceramics show excellent electrical properties: d33 = 355 pC/N, Qm = 936, kp = 58.4%, tanδ= 0.32%, andε33^T= 1590. On the other hand, the effect of Nb2O5 on piezoelectric properties is much complicated, 0.50 wt% Nb2O5 doped 0.90PZT-0.05PMS-0.05PZN + 1.0 wt% CuO ceramics have a remarkable improvement in kp value and maintain good electrical properties: d33 = 300 pC/N, Qm = 971, kp = 58.4%, tanδ= 0.36%, andε33^T = 1332.</sub>更多还原