Dielectric and ferroelectric characteristics of [(Bi0.5Na0.5)0.94Ba0.06]1−xSrxTiO3 ceramics

Effects of Sr-substitution upon dielectric and ferroelectric characteristics of (Bi0.5Na0.5)0.94Ba0.06TiO3 ceramics have been investigated together with the structure. [(Bi0.5Na0.5)0.94Ba0.06]1−xSrxTiO3 solid solutions are formed in the entire composition range investigated here (x = 0–0.3), and there are two kinds of symmetries: P4bm and R3c. A morphotropic phase boundary separating P4bm and R3c is observed at x = 0.025. There are two dielectric anomalies in the permittivity versus temperature curve. Sr-substitution significantly enhances the low-temperature dielectric relaxation (around T d ) and lowers the phase transition temperature (high-temperature dielectric anomaly at T m ). The saturated polarization–electric field (P–E) hysteresis loops are determined further below T d , and the pinched P–E hysteresis loops are generally indicated between T d and T m . With increasing Sr-content, T d increases at first and then turns to decrease above x = 0.10, while T m decreases continuously. Moreover, the pinched P–E hysteresis loops become very weak at x > 0.25. Sr-substitution changes the stabilization of the nonpolar state above T d , and suppresses the electric field induced phase transition.