Phase transition and electrical properties of high performance, high temperature Bi(mg,Ti)O₃-PbTiO₃-PbZrO₃ relaxor ferroelectric ceramics

Traditional Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ based relaxor ferroelectrics have attracted much attention. However, the relatively low T_m restricts their application in the high temperature range. In the present study, a novel (0.8-x)Bi(Mg_1/2Ti_1/2)O₃-xPbTiO₃-0.2PbZrO₃ ((0.8-x)BMT-xPT-PZ) relaxor ferroelectric based on the high temperature BMT-PT piezoelectrics was designed. All samples exhibit pure perovskite structures and the phase structures show a gradual transition from relaxor rhombohedral (R) to normal tetragonal (T) phases via the morphotropic phase boundary (MPB) in the composition range x = 0.36–0.39. The dielectric relaxation behavior can be observed in all samples although a spontaneous normal-relaxor ferroelectric transformation is observed in the T phase region. The x = 0.38 sample exhibits the optimal overall electrical properties with the d₃₃ value of 325 pC/N, the k_p value of 0.38, the T_m value of 290 ^oC. The results indicate that the present studied ternary system has a good potential as high temperature relaxor ferroelectrics.