【作者】 郭炜；

【导师】 李玲霞；

【作者基本信息】 天津大学 ， 微电子学与固体电子学， 2004， 硕士

【摘要】 本论文利用先驱体B位复合取代法制备高介（Ni1/3Nb2/3）O3-（Mn1/3Nb2/3）O3-BaTiO3系统陶瓷材料，并在此基础上加入适量助熔剂以改变其烧结特性，制备出中温烧结X7R瓷料，同时对先驱体合成取代机理及系统介电性能进行了分析。利用先驱体掺杂细晶BaTiO3进行改性可以避免钙钛矿结构陶瓷烧成过程中焦绿石相对系统介电性能的严重影响。由于（Ni1/3Nb2/3）O3与（Mn1/3Nb2/3）O3的居里点在负温，因此系统中先驱体取代后形成的Ba（Ni1/3Nb2/3）O3与Ba（Mn 1/3Nb2/3）O3的居里峰将向负温方向移动。根据居里峰的叠加效应，可使（Ni1/3Nb2/3）O3-（Mn 1/3Nb 2/3）O3- BaTiO3系统提高室温下的介电常数。另一方面，先驱体（Ni1/3Nb2/3）O3与（Mn1/3Nb2/3）O3的平均离子半径分别为（0.0707nm）与 (0.0697nm)，尺寸接近且均大于Ti4+(0.061nm)的离子半径，这些半径较大的离子复合取代Ti4+后将使其所在处的八面体扩张，相应的使相邻以Ti4+为中心的八面体受到压缩，使局部失去了铁电性，表现为ε峰值降低，温度特性平坦，峰值两侧肩部上举，从而起到了展宽居里峰的作用。两种先驱体协同改性可使系统如下性能，烧结温度 1290℃：介电常数：ε≥5000 容量变化率：ΔC/C≤±15%（-55℃～+125℃） 介质损耗：tgδ≤1.2% 绝缘电阻率：ρv≥1011Ω·cm为了进一步降低烧结温度，以便采用较便宜的70%Ag-30%Pd电极，在上述高介瓷料中添加适量助熔剂，使系统的烧结温度降至1150℃，所得系统的介电性能如下，烧结温度 1150℃：介电常数：ε≥3600 容量变化率：ΔC/C≤±15%（-55℃～+125℃） 介质损耗：tgδ≤1.2% 绝缘电阻率：ρv≥1012Ω·cm更多还原

【Abstract】 In this paper, the way of B-site substitution using precursor in （Ni1/3Nb2/3）O3-（Mn1/3Nb2/3）O3-BaTiO3 system was studied. On the basis of this system, X7R ceramics with prefect dielectric properties were achieved at intermediate temperature range. Meanwhile, the mechanics of precursor replacement of B-site ion was also discussed.The formation of some unexpected transition phase do harm to dielectric properties of system in sintering process, which can be avoided by doping with precursor in fine-grained BaTiO3. After substitution precursor for Ti4+, the Curie peak of Ba（Ni1/3Nb2/3）O3 and Ba（Mn 1/3Nb2/3）O3 were shifted to negative temperature. Moreover, the dielectric constant was improved greatly at room temperature because of the superposition effection. On the other hand, the average ionic radius of Ba（Ni1/3Nb2/3）O3 (0.0707nm)and Ba（Mn 1/3Nb2/3）O3 (0.0697nm)were similar and greater than Ti4+(0.061nm). The octahedron was enlarged after these big ions substituting partly for Ti4+. Other neighbor octahedrons can be compressed and the movement of Ti4+ in center was limited. To some extent, part of ferroelectricity was disappeared. This can reduce the dielectric constant, broaden the Curie peak and flatten the temperature dependence curve. The dielectric properties are as follow:ε≥5000 ΔC/C≤±15% （-55℃～+125℃） tgδ≤1.2% ρv≥1011Ω·cmThe flux was also used in order to reduce the sinter temperature to 1150℃. Under this sintering condition, cheaper electrode such as 70%Ag-30%Pd can be utilized to produce intermediate temperature sintered porcelain. This kind of material must be made good use of in EMI capacity filter. The dielectric properties in system are as follow:ε≥3600 ΔC/C≤±15% （-55℃～+125℃）tgδ≤1.2% ρv≥1012Ω·cm更多还原