B_(0.7)Sr_(0.3)TiO_3(BST) and Ba_(0.7-x)Pb_xSr_(0.3)TiO_3CBPST) ceramics derived from different amount of initial PbO excess were prepared by conventional solid-state method. Both permittivity and dielectric loss of all samples were measured in a temperature range. The substitution of Pb for Ba in BST system has revealed to raise the Curie temperature from 44-175'C ,and exhibited a diffused phase transition(DPT), expecially for the ceramic Ba_(0.5) Pb_(0.1) TiO_3 which can improve the temperature stability of tunability for phase shifter than others. Moreover,some ferroelectric model parameters were calculated to interpret the DPT by adopting Smolenski' s theory and Curie-Wise law. For example,values of diffuseness exponent a,Curie constant and transition region have varied from 1.29-1. 88,from 1. 25×10~5-1. 47×10~5K,and from 13.4-22. 8℃,respectively.%用固相反应法制备了Ba_(0.7)Sr_(0.3)TiO_3及其含Pb钛酸锶钡(BPST)陶瓷,运用修正的Smolenski的成分起伏理论和居里外斯定律,结合介电常数温度谱,研究了钙钛矿结构的BST及铅取代的钛酸锶铅钡(BPST)的弥散相,对其相变行为进行了分析,得出了的一些铁电模型参数.结果表明,该系列样品在弥散相变区的弥散指数α为1.29～1.88,相变区间为13.4～22.8℃;在顺电相其居里常量为1.25×10~5～1.47×10~5K数量级.当Pb含量为0.1(即Ba_(0.6)Pb_(0.1)TiO_3)时,居里峰较宽,弥散相明显,故具有较高的调谐温度稳定性.另外铅的加入提高了铁电体的相变温度,从44℃上升到175℃.
展开▼
