Effect of some dopants on temperature of high-temperature phase transitions of Na_0.5Bi_0.5TiO₃-0.06BaTiO₃ lead-free relaxor ferroelectrics ceramics seen via acoustic emission

Na_0.5Bi_0.5TiO₃-0.06BaTiO₃ relaxor ferroelectrics ceramic samples doped with 1 wt% of CuO, Fe₂O₃, Sb₂O₃, La₂O₃ and Ta₂O₅ were investigated by means of dielectric and acoustic emission methods in the high-temperature range. Dielectric constants exhibited a wide and smeared maximum at the temperature T _m, accompanied by acoustic emission sharp bursts, but the dielectric constants exhibited no anomaly when further transiting into cubic paraelectric phase at the temperature T _p, accompanied by acoustic emission sharp bursts, too. Based on acoustic emission data the shifts of these two temperatures, T _m and T _p, in dependence on a wt% of the incorporated ions as well as the acoustic emission count rate distribution in dependence on the incorporated ions radii were plotted and discussed.