【作者】 金向峰；

【导师】 吕文中；

【作者基本信息】 华中科技大学 ， 微电子学与固体电子学， 2007， 硕士

【摘要】 采用传统的陶瓷工艺,对Bi1/2Na1/2TiO3(BNT)陶瓷进行A位取代,制备了Bi1/2(Na1-xLix)1/2TiO3(BNLT)无铅压电陶瓷,并研究该陶瓷的铁电特性、介电性能、压电性能以及微观结构。在此BNLT无铅压电陶瓷基础上进行CeO2,La2O3和Co2O3掺杂,得到性能改进的BNLT陶瓷,并初步探讨了掺杂改性的机理。BNLT陶瓷的电滞回线曲线表明Li+离子部分取代Na+离子能降低该体系陶瓷样品的矫顽场强,从而提高BNT陶瓷的压电性能。XRD结果表明,在x=0～0.20时,Bi1/2(Na1-xLix)1/2TiO3陶瓷为单相三方晶系钙钛矿结构,在x=0.30时,会有影响压电性能的杂相产生。SEM结果表明,Li含量越高,陶瓷的烧结温度越低,Li促进了晶粒特定方向的生长。x= 0.15时,压电系数d33达到极大值109 pC/N。介电温谱表明BNLT陶瓷应该是一种弛豫型铁电体。同时研究极化工艺条件对材料压电性能的影响。在BNLT无铅压电陶瓷中掺入CeO2,La2O3和Co2O3。结果表明一定量CeO2的掺入能同时提高压电常数d33和机械品质因数Qm,以及相对介电常数εr,并减小了介电损耗tanδ。La2O3的掺入,可以提高BNLT15陶瓷的压电常数d33和机械品质因数Qm。但随着La2O3掺入量继续增大,性能急剧下降。从本实验结果来看,La2O3的掺入量选取在0.2wt%比较适合。Co2O3的掺入,可以提高BNLT15陶瓷的压电常数d33和相对介电常数εr。尤其值得注意的是,Co2O3的掺入能够显著地提高机电耦合系数kp。其中一组配方BNLT15-0.8wt% Co2O3陶瓷,其压电常数d33为115 pC/N,机电耦合系数kp为0.31,相对介电常数εr为991.8,比掺杂之前分别提高6%,70%和45%。更多还原

【Abstract】 Lead-free piezoelectric ceramics Bi1/2(Na1-xLix)1/2TiO3 (BNLT)were prepared by the conventional ceramic sintering technique. The Li+ substituted Na+ at the A sites of the perovskite structure. The ferroelectric properties, dielectric properties, piezoelectric properties and microstructures of these piezoelectric ceramics were studied. BNLT ceramics doped with CeO2, La2O3 and Co2O3 were also studied, the piezoelectric properties and dielectric properties of these piezoelectric ceramics has been improved.The result on observation of P-E hysteresis loops indicates that while some Li+ ions substituted Na+ ions ,the remanent polarization Pr of BNLT ceramics is increased, and the coercive field Ec is decreased, which enhances piezoelectric properties. From the result of XRD, it was found that Bi1/2(Na1-xLix)1/2TiO3 ceramics show a single phase of perovskite structure with a rhombohedral symmetry in the range of x=0~0.20. Other phases which decrease piezoelectric properties of ceramics was found at x=0.30. From the result of SEM, the sintering temperature decreases with the increasing amounts of Li, and Li promotes the growth in some directions of crystalline grains. The measurements results of piezoelectric properties reveal that d33 reach a maximum 109 pC/N at x=0.15. The temperature dependence of dielectric constant were measured, it is found that the ceramics are relaxor ferroelectric. The effects of poling technique on the piezoelectric properties in the system were also investigated.Lead-free piezoelectric ceramics Bi1/2(Na1-xLix)1/2TiO3 (BNLT)doping with CeO2 were prepared by the conventional ceramic sintering technique. It is concluded that with the addition of proper amount of CeO2, the piezoelectric constant d33, the mechanical quality factor Qm and the dielectric constantεr are increased, and the dielectric loss tanδis decreased.Lead-free piezoelectric ceramics Bi1/2(Na1-xLix)1/2TiO3 (BNLT)doping with La2O3 were prepared by the conventional ceramic sintering technique. It is concluded that with the addition of proper amount of La2O3, the piezoelectric constant d33, the mechanical quality factor Qm are increased. But the piezoelectric properties and dielectric properties are decreased quickly when the amount of La2O3 is larger than 0.2wt%.更多还原