【作者】 张玉平；

【导师】 李月明；

【作者基本信息】 景德镇陶瓷学院 ， 材料学， 2007， 硕士

【摘要】 本文采用传统电子陶瓷方法制备了偏铌酸铅（PbNb₂O₆，简称PN）基高居里温度压电陶瓷，系统研究了材料的制备工艺与结构、压电性能的关系，分析了PN基陶瓷的组成、结构与压电性能之间的联系，并结合实验结果探讨了PN基陶瓷的铁电性对压电性能的影响。研究了PN基陶瓷的合成温度、烧成温度、冷却方式对样品晶体结构与压电性能的影响。结果表明：合适的合成温度为850～900℃，保温2h，陶瓷的烧结温度在1245～1255℃，保温2h，通过掺杂使PN基压电陶瓷在自然冷却的条件下形成具有铁电性的斜方钨青铜结构。研究了极化工艺条件对PN基陶瓷压电性能的影响，发现极化电场强度和极化温度对陶瓷的压电性能有较大的影响，而极化时间的影响相对较小。适宜的极化电场是4.5 kV／mm，极化温度为160～170℃，极化时间为15 min。研究了0.3 wt％MnO₂-(Pb_1-xBa_x)Nb₂O₆体系（简称PBMN）陶瓷的结构、压电及其介电性能。XRD分析表明，经过烧结，PBMN体系由合成时的三方非铁电相转变为斜方铁电相。陶瓷材料的居里温度测试结果表明该体系具有较高的居里温度T_c（490～550℃），其压电性能随着Ba²⁺掺入量的增加明显提高，当x=0.05 mol时，陶瓷的压电常数d₃₃达到最大值，为70 pC／N，居里温度T_c为510℃，介电常数ε₃₃ ^T／ε₀=326，介质损耗tanδ为1％。研究了（1-2y）PbNb₂O₆-ySrTiO₃-yTiO₂体系（简称PST）陶瓷的结构、压电、介电及其铁电性能。测定了该体系陶瓷材料在1、10、100 kHz下的介电常数-温度曲线，发现该体系陶瓷是一类弛豫型铁电体材料，并具有较高的居里温度T_c（500～560℃）。同时，Sr²⁺和Ti⁴⁺的掺杂降低了PN陶瓷的剩余极化强度P_r和矫顽电场E_c，当y=0.02时具有较高的剩余极化强度P_r和较低的矫顽电场E_c，相应的材料的压电、介电性能最好，压电常数和机电耦合系数达到最大值，分别为d₃₃=83 pC／N，k_t=34.9％；机械品质因数和介质损耗达到最小值，分别为Q_m=12，tanδ=1.5％，并具有较高的居里温度T_c=550℃。更多还原

【Abstract】 In this dissertation, lead metaniobate （PbNb₂O₆ （PN）） based piezoelectric ceramic with high Curie temperature were synthesized by conventional ceramics preparation technique. The relations among preparation method, crystal structure and the piezoelectric properties were investigated, and the relations among the composition, the crystal structure and the piezoelectric properties were also studied. The effect of ferroelectric feature on the piezoelectric properties has been established in terms of experimental results.The dependence of crystal structure and piezoelectric properties on synthesized temperature, sintering temperature and cooling method of PN-based ceramics was studied. The results show appropriate synthesized temperature is in the range of 850 900℃for 2 h and sintering temperature for ceramic is in the range of 1245～1255℃for 2 h. The orthorhombic symmetry tungsten bronze structure with ferroelectric characteristic of the PN-based ceramic is obtained at furnace-cooling condition. The piezoelectric properties of the PN-based ceramics highly depend on poling field and temperature, while no remarkable effect of poling time on the piezoelectric properties. Appropriate poling field is 4.5 kV/mm, poling temperature is 160～170℃and poling time is 15 min.The structure, piezoelectric and dielectric properties of 0.3wt%MnO₂-(Pb_1-xBa_x)Nb₂O₆ （PBMN） ceramics were investigated. XRD results reveal that the crystal structure of ceramics transformed from rhombohedral non-ferroelectric to orthorhombic ferroelectric by sintering. The result of dielectric constant vs temperature shows that all the compositions have a high Curie temperature in the range of 490～550℃. The piezoelectric properties of PBMN ceramics have been enhanced with the increasing of dopant Ba²⁺ content. When x=0.05, the piezoelectric constant d₃₃ attains 70 pC/N which is the maximum of all the compositions, the Curie temperature T_c is 510℃, the dielectric constantε₃₃^T/ε₀ is 326 and dielectric loss tang is 1%.The crystal structure, piezoelectric, dielectric and ferroelectric properties of （1-2y）PbNb₂O₆-ySrTiO₃-yTiO₂ （PST） ceramics were also studied. The dependence of dielectric constant and temperature at 1、10、100 kHz frequency was analysized, respectively. It is found that this system ceramics are relaxational ferroelectric materials and they have high Curie temperature about 500～560℃. It is showed that it has the relatively higher remanent polarization P_r and relatively lower coercive field E_c from P-E hysteresis loops results at y=0.02. This material has good piezoelectric and dielectric properties of which are piezoelectric constant d₃₃=83 pC/N, electromechanical coupling factor k_t=34.9%, mechanical quality factor Q_m=12, dielectric loss tanδ=1.5% and the Curie temperature T_c=550℃, respectively.更多还原