Enhanced piezoelectric and ferroelectric properties of BiFeO3-BaTiO3 lead-free ceramics by optimizing the sintering temperature and dwell time

0.7BiFeO3-0.3BaTiO3 (BFO-0.3BT) ceramics were prepared to uncover the impacts of sintering temperature (TS) and dwell time (td) on the microstructure and electrical properties. With increasing the TS or td, the grain sizes increase along with the porosity decreases, which is in favor of the alignment of dipole. However, excess TS or td are inclined to cause the volatilization of Bi2O3, which deteriorates piezoelectric properties. Because of the R-T two-phase coexistence, low defect ions concentration and porosity, as well as appropriate grain size, the excellent d33 = 208 pC/N and kp = 35.46% as well as Pr = 28.52 μC/cm2 were achieved in BFO-0.3BT ceramics at TS = 1000 °C and td = 6 h. In addition,large unipolar strain 0.13% and d33* = 256.2 pm/V also were obtained in BFO-0.3BT ceramics at TS = 1000 °C and td = 6 h. This research indicates that the porosity and defect ion concentration as well as grain size also play an important role in piezoelectric properties in BFO-BT ceramics.