(Ba_(1-x)Sr_(x/2)Ca_(x/2))TiO_3陶瓷的介电弛豫特征和铁电性能

DIELECTRIC RELAXATION AND FERROELECTRIC PROPERTIES OF (Ba_(1-x)Sr_(x/2)Ca_(x/2))TiO_3 CERAMICS

采用传统陶瓷的制备方法,制备了(Ba1-xSrx/2Cax/2)TiO3(x=0.10,0.20,0.40,0.50,0.60)铁电陶瓷。X射线衍射分析表明:x=0.20时,陶瓷样品具有三方、四方共存的晶体结构。不同频率下陶瓷样品的介电温谱显示(Ba1-xSrx/2Cax/2)TiO3材料具有弥散相变的特征,在x=0.60时,(Ba1-xSrx/2Cax/2)TiO3陶瓷具有典型的弛豫铁电体特征。研究发现:当x=0.20时,(Ba1-xSrx/2.Cax/2)TiO3陶瓷材料的矫顽电场达到极小值。基于极性纳米微区理论的观点,进一步研究了弛豫铁电体和具有弥散相变铁电体两者之间的关系,结果表明:仅仅当实验频率和极性纳米微区的弛豫频率相近时,在弥散相变温区内介电弛豫行为才能被观察到。

Ferroelectric ceramics （Ba1-xSrx/2Cax/2）TiO3 （ x= 0.10,0. 20,0. 40,0. 50,0. 60 ） were prepared by a conventional ceramics preparation technique. X-ray diffraction analysis indicates that the ceramics sample of x=0.20 has a coexisting rhombohedral and tetragonal crystal structure. The dielectric constants as a function of temperature at different frequencies show that the ceramics have characteristics of ferroelectrics with diffused phase transition, and the ceramics sample of x=0.60 exhibits a typical relaxor ferroelectric behavior . The lowest value of the coercive field is obtained at x=0.20. The relationship between ferroelectrics with diffused phase transitions and relaxor ferroelectrics was investigated. Dielectric relaxation can be observed only when the experimental frequency is close to the relaxation frequency of the polar nano-microregion at the temperature of the diffused phase transition.