Acoustic emission pronounced field‐induced response near critical point in Ba 0.6 Sr 0.4 TiO 3 ferroelectrics

Ba 0.60 Sr 0.40 TiO 3 ceramic ferroelectric (FE) has been investigated in the wide temperature range under a dc external electric field ( E ) by means of dedicated acoustic emission (AE) method. The Curie point T c  = 9 °C, as well as both the temperature points, characteristic of relaxor ferroelectrics (RFEs), Burns temperature T d  = 283 °C and intermediate temperature T * = 182 °C have successfully been detected. T c demonstrates a nontrivial behavior in dependence on E , i.e., initially it decreases, reaches a minimum of T th  = 1.2 °C at the small threshold field E th  = 0.75 kV cm −1 , and then starts to increase similar to ordered FEs, as E increases. The AE count rate, accompanying this nontrivial behavior of T c ( E ) dependence, exhibits a pronounced maximum ≈5.4 s −1 above E th at the E m  = 1.5 kV cm −1 . Both, T d and T * demonstrate a dependence on E , too, as was recently observed in relaxor FEs PbSc 0.5 Nb 0.5 O 3 [Dul'kin et al., J. Appl. Phys. 113 , 054105 (2013)]. The AE pronounced maximum is explained to be a consequence of the giant piezoelectric coefficients intrinsic to Ba x Sr 1− x TiO 3 FEs.