Detecting the Burns temperature in Na_0.5Bi_0.5TiO₃-xBaTiO₃ lead-free relaxor ferroelectrics by means of acoustic emission

Na_0.5Bi_0.5TiO₃-xBaTiO₃ ceramics samples (0< x < 0.8) were studied by means of an acoustic emission method. The characteristic temperatures such as the Burns temperature, T _B, the transition to paraelectric phase, T _p, the temperature maximum of the dielectric constant, T _m, and the intermediate temperature, were detected and their dependences on x were plotted. Based on the comparison of the obtained data with the previously published ones, it is shown that the Burns temperature, T _B, cannot be reliably determined by the deviation of the reverse dielectric constant, , from a straight line.