【作者】 刘培祥；

【导师】 孙清池；

【作者基本信息】 天津大学 ， 材料学， 2007， 硕士

【摘要】 本文选取0.25Pb(Mg_1/3Nb_2/3)O₃-0.15Pb(Ni_1/3Nb_2/3)O₃-（0.6-x）PbZrO_3-xPbTiO₃（简称PMN-PNN-PZT）体系压电陶瓷作为研究对象,研究了Ti/Zr对系统准同型相界及压电、介电性能的影响。通过研究得出:当Ti/Zr介于1.55和1.655之间时,物相由三方相向四方相转变,系统处于准同型相界处。材料性能尤以Ti/Zr=1.643时最好:ε₃₃^T/ε₀=3384、d₃₃=477pC/N、K_p=0.56、Q_m=82、tanδ=2.3%、T_c=205℃。通过对比前驱体合成工艺与传统的氧化物混合合成工艺对系统相结构、微观形貌、压电和介电性能的影响发现:前驱体合成工艺能更好的避免焦绿石相的生成,有效保证化学计量比的稳定,并能抑制内部晶粒的过大生长和促进晶界致密化,对压电陶瓷性能的提升较为明显。另外,本文还研究了烧结温度对压电陶瓷系统微观结构和性能的影响,结果表明:最佳烧结温度是1180℃。此时晶粒生长的均匀致密,粒径大小在（3～5）μm。此烧结温度下测得压电陶瓷样品的体积密度最大,为7.89g/cm³,气孔率最低,为3%。最后,本文还对不同氧化物掺杂剂对PMN-PNN-PZT体系压电陶瓷的掺杂改性进行了研究。通过分析掺杂物La₂O₃,ZnO和CeO₂对材料性能的影响,并结合X衍射分析图和扫描电子显微镜图得出:La₂O₃最佳的掺杂量为0.6wt%,ZnO最佳的掺杂量为0.4wt%,CeO₂的最佳掺杂量为0.10wt%,过多的掺杂物将在晶界处偏析,影响材料的性能。比较各掺杂物的影响结果,以0.10wt% CeO₂的掺杂对材料性能的提升最为明显:ε₃₃^T/ε₀=3640、d₃₃=507pC/N、K_p=0.61、Q_m=116、tanδ=1.0%、T_c =222℃。CeO2掺杂能促进晶粒的生长,最大晶粒直径能达到20μm,它对材料性能的影响总体表现出“软性掺杂”和“硬性掺杂”的特性。更多还原

【Abstract】 0.25Pb(Mg_1/3Nb_2/3)O₃-0.15Pb(Ni_1/3Nb_2/3)O₃-（0.6-x）PbZrO_3-xPbTiO₃ （abbreviated as PMN-PNN-PZT） piezoelectric ceramics was selected as research object, the effect of Ti/Zr ratio on its morphotropic phase boundary ,dielectric and piezoelectric properties was studied.The results show that the system lies in morphotropic phase boundary when Ti/Zr ratio is between 1.55 and 1.655,while rhombohedral phase transforms into tetragonal phase.The best properties are abtained when Ti/Zr=1.643:ε₃₃^T/ε₀=3380,d₃₃=477pC/N,K_p=0.56,Q_m=82, tanδ=2.3%,T_c=205℃.In the paper, the effect of precursor synthesis process compared with oxide compound synthesis process on phase structure, microstructure and properties of PMN-PNN-PZT ceramics was investigated.The experiment indicates that the precursor synthesis process can avoid Pyrochlore Phase, stabilize the chemistry matching,inhibit the big grain growth and improve sintering densities, the material properties can be improved greatly by the process.Also,the effect of sintering temperature on microstructure and material properties was discussed,it is found that, sintered at 1180℃,the crystals is dispersive well ,the average grain size is （3～5）μm and the biggest volume density is 7.89g/cm³ ,while the porosity is lowest, 3%.In the end, the doping modification of PMN-PNN-PZT system piezoelectric ceramics was studied. Some conclusions can be drawed by analyzing the influence of the oxide dopants as La₂O₃,ZnO and CeO₂ upon the material properties,also combining SEM and XRD pictures: the optimal doping amount of La₂O₃,ZnO and CeO₂ is 0.6wt%,0.4wt% and 0.10wt% respectively.Excessive amount of dopants will assemble in the crystal boundary and influence material properties.The material properties can be improved obviously with 0.10wt% CeO₂ doping compared with other dopants:ε₃₃^T/ε₀=3640、d₃₃=507pC/N、K_p=0.61、Q_m=116、tanδ=1.0%、T_c =222℃.The CeO₂ doping can promote crystal grain growth, the biggest crystal grain diameter can attain 20μm.The behavior effect of CeO2 doping on material properties are explained by soft doping and hard doping mechanism.更多还原