Abstract :
The dielectric and ferroelectric properties of Ba1−xSrxTiO3 (BST) ( x = 0.10 , 0.20 , 0.30 , 0.40 and 0.60) ceramics and Ba1−2xSrxCaxTiO3 (BSCT) ( x = 0.10 , 0.20 , 0.30 ) ceramics have been investigated. The low temperature phase transitions of BST ceramics vanish after Ca2+ substitution while the high temperature transition is diffused and relaxed, which becomes more obvious with increasing x . Ca2+ substitution obviously decreases the dielectric constant maximum, K m , of BST ceramics and changes the temperature of dielectric constant maximum, T m , of BST ceramics. The shift of T m in BST is attributed mainly to the Sr2+ and Ba2+ concentration. BST ceramics exhibit almost normal ferroelectric characteristics, while a typical relaxor behavior was observed in BSCT ceramics. The relaxor behavior observations may be understood by a random electric field induced domain state.
