The structure, electrical properties and phase diagram of Sm-modified BiFeO₃-PbTiO₃ solid solution ceramics

BiFeO₃-PbTiO₃ based materials attract lots of research interests due to the rich structure and properties variants. In this work, a series of 0.55Bi_1-xSm_xFeO₃-0.45PbTiO₃ solid solution ceramics with x = 0.1–0.3 are synthesized by sintering method. X-ray diffraction results show the phase evolution with the existence of rhombohedral and tetragonal phase in the composition range (i.e., morphotropic phase boundary, MPB) of x = 0.125–0.175. Both ferroelectric and piezoelectric properties are enhanced when approaching to MPB. Moreover, the additional thermal treatments including oxygen annealing and quenching processes are successfully employed to obtain further enhanced properties with remnant polarization P_r = 38.8 μC/cm² and piezoelectric coefficient d₃₃ = 131 pC/N. Finally, the phase diagram of the ternary system BiFeO₃-SmFeO₃-PbTiO₃ is constructed based on the results in this work and literatures, which could be valuable for efficiently developing BiFeO₃-PbTiO₃ based ferroic materials with desired properties.