Enhanced piezoelectric properties of BiFeO3-BaTiO3 lead-free ceramics by shifting phase boundary via simultaneous adjusting component and quenching technique

The morphotropic phase boundary (MPB) is particularly crucial for high piezoelectric performance of perovskite ferroelectrics. This study focus on the shift of MPB and its impacts on the piezoelectric properties of (1-x)Bi0.997La0.003FeO3-xBaTiO(3) ferroelectric ceramic. Although appropriate La doping reduces leakage current, the phase boundary is moved towards tetragonal (T) phase. By adjusting BaTiO3 component, the concentration of rhombohedral (R) and T phase is restored back to almost equality at x = 0.295, achieving optimal piezoelectric properties (d(33) = 179 pC/N, k(p) = 33.06 %). Furthermore, through applying quenching on 0.30 <= x <= 0.32 samples occupied mainly by T phase, a higher d(33) value of 205 pC/N and a remarkable amplification of d(33) (about 40 %) are both realized at x = 0.32, which is ascribed to the shift of R/T phase ratio close to 1:1. These results confirm the importance of phase boundary movement and provide an effective approach for performance enhancement of BiFeO3-BaTiO3 system.