Relaxor–ferroelectric crossover seen via characteristic temperatures of Ba x Sr 1– x TiO 3 ferroelectrics detected by acoustic emission

Ba x Sr 1– x TiO 3 ferroelectrics ceramic with x  = 70 and 80% have been studied by means of acoustic emission over a wide 0–300 °C temperature range and under dc external electric field. All the Curie temperatures T c , intermediate temperatures T * , and Burns temperatures T d have been successfully detected and compared with those previously detected in Ba x Sr 1– x TiO 3 with x  = 60% and pure BaTiO 3 , using the acoustic emission. For all the compounds, the critical end points at which the strains are expected to be largest, have been successfully detected, too. While the T c linearly increases as x increases, it was established that both the T * and T d exhibit nonlinear behavior: they initially decrease, attain the minima near x  ≈ 70% and then start to increase and tend to those, corresponding to pure BaTiO 3 , as it was previously reconstructed for T d in BaZr x Ti 1– x O 3 compound [Shvartsman and Lupascu, J. Am. Ceram. Soc. 95 , 1 (2012)]. Such a phenomenon is discussed from the viewpoint of the presence of polar nanoregions, intrinsic to pure BaTiO 3 in the paraelectric phase, and it is concluded, that a minimum in both the T * ( x ) and T d ( x ) dependences points out a range of relaxor–ferroelectric crossovers in Ba‐based compounds.