添加KNN和BBS对BaTiO3陶瓷微结构和介电性能的影响

摘要

BaTiO3 (BT) capacitor ceramics with Kc.5Nao.5NbO3 (KNN) and BBS glass (BBS) were prepared by the solid state reaction route. The effects of doping KNN and BBS on the crystal structure, microstructure and dielectric properties were investigated by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and impedance analyzer. The results show that KNN-doped BT ceramics exhibit pure perovskite structure. AC/C25x: values at high temperature obviously decrease with increasing KNN content. 3%-5% (mole fraction) KNN-doped BT ceramics are satisfied with the EIA X7R specification. Adding 1% (mass fraction) BBS and 3% (mole fraction) KNN have no effect on the crystal structure of BT ceramic. However, the secondary phases, Bi1B9 and BaTi5On, occur when BSS content is more than 3% (mass fraction). BT ceramic sample with 3%BBS (mass fraction) and 1%KNN (mole fraction) sintered at 1 100 V shows medium dielectric constant (1 045), low dielectric loss (0.74%), high volume resistivity (5.5X 1011 12cm). The variation of dielectric permittivity for BT-KNN ceramic compared with room temperature is about —6.6% at —55 The, -1.7% at 125 t and -13.2% at 150 °C. The as-prepared ceramic material has great potential as X8R multilayer ceramic capacitors at intermediate temperature.%采用固相法制备添加K0.5Na0.5NbO3(KNN)和BBS玻璃(BBS)的BaTiO3电容器陶瓷.借助X射线衍射仪、扫描电镜和阻抗分析仪研究掺杂对晶体结构、微观组织及介电性能的影响.结果表明:单独添加KNN的样品呈单一的钙钛矿结构.随KNN的增加,陶瓷样品高温端的电容变化率减小.掺杂3％～5％KNN(摩尔分数)陶瓷满足X7R特性.掺杂1％BBS(质量分数)对含3％KNN(摩尔分数)陶瓷的晶体结构无影响.BBS超过3％(质量分数)时,有第二相Bi4B2O9和BaTi5O11生成.1 100℃烧结掺杂3％BBS(质量分数)和1％KNN(摩尔分数)的BaTiO3陶瓷具有中等介电常数(1045),低的介电损耗(0.74％)和较高的体积电阻率(5.5×1011 Ω.cm),在-55、125和150℃的电容变化率分别为-6.6％、-1.7％和-13.2％,有望用于中温制备的X8R型多层陶瓷电容器.