Bi掺杂SrTiO_3陶瓷缺陷结构模拟及介电性能研究

Study on Defect Structure Atomistic Simulation and Dielectric Properties of Bi Doped SrTiO_3 Ceramics

采用固相反应制备Sr_(1-x)Bi_xTiO_3陶瓷,研究Bi掺杂对SrTiO_3的介电性能、缺陷结构及缺陷偶极子的影响。通过X线衍射(XRD)分析其物相结构,表明在掺杂浓度范围内均未出现第二相。通过GULP模拟,得到Sr_(1-x)Bi_xTiO_3中可稳定存在的缺陷偶极子有[2Bi_(Sr)~·+V_(Sr)″]、[V_O^(··)+V_(Sr)″]、[2V_O^(··)+V_(Ti)″″]和[V_O^(··)+2 Ti_(Ti)']。各组掺杂陶瓷样品的弛豫特性均满足Arrhenius定律,这是弛豫受热激发所致,随着Bi掺杂量的增加弛豫激活能增加,弛豫度减小。

Sr1-xBixTiO3 ceramics were prepared by conventional solid state reaction. The dielectric properties, defect structure and defect dipoles of SrTiO3 ceramics doped with Bi were investigated. The crystal structure were characterized by X - ray diffraction （XRD）. The results show that the second phase does not occur in doping range. Obtained by the General Utility Lattice Program, the stable defect dipoles are [ 2 BiSr ＋ VSr ], [ Vo＂ ＋ Vsr ], [ 2Vo＇ ＋ VTi ] and [ Vo＂ ＋ 2 Ti＇Ti ]. The results suggest that all the dielectric relaxations are related to the thermally activated process by following Arrhenius law. With the content of Bi increasing, the relaxation activation energy of the peaks of dielectric loss increases and the degree of dielectric relaxation decreases.