Detection of the critical end point in PbSc_0.5Ta_0.36Nb_0.14O₃ relaxor ferroelectrics crystals via acoustic emission

PbSc_0.5Ta_0.36Nb_0.14O₃ relaxor-ferroelectric crystals were studied by the means of dielectric and acoustic emission (AE) methods in the temperature range of 180-300 K. In zero dc electric field (E) no AE was detected at the smeared dielectric maximum Tm≈260K characteristic for canonical relaxor ferroelectrics. Under the E a phase transition appears at T_C = 217K for E∼1 kVcm^-1. The T_C(E) dependence is linear with an anomaly point at E∼1.3 kV cm^-1, at which dT_C/dE abruptly changes. At this E value the AE rate exhibits a maximum. The anomalous E point is assigned to be the critical end point for this solid solution.