Acoustic emission pronounced field-induced response near critical point in Ba0.6Sr0.4TiO3 ferroelectrics



Ba0.60Sr0.40TiO3 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 Tc = 9 °C, as well as both the temperature points, characteristic of relaxor ferroelectrics (RFEs), Burns temperature Td = 283 °C and intermediate temperature T* = 182 °C have successfully been detected. Tc demonstrates a nontrivial behavior in dependence on E, i.e., initially it decreases, reaches a minimum of Tth = 1.2 °C at the small threshold field Eth = 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 Tc(E) dependence, exhibits a pronounced maximum ≈5.4 s−1 above Eth at the Em = 1.5 kV cm−1. Both, Td and T* demonstrate a dependence on E, too, as was recently observed in relaxor FEs PbSc0.5Nb0.5O3 [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 BaxSr1−xTiO3 FEs.