Quenching and Electrical Current Poling Effect on Improved Ferroelectric and Piezoelectric Properties in BiFeO₃-Based...

The effects of quenching on the structural, electrical, dielectric, ferroelectric (FE), and piezoelectric properties are investigated systematically in the 0.85BiFe_1-CrO₃-0.15BaTi_1-MnO₃ (0 ≤ x ≤ 0.03) ceramics. Optimal piezoelectricity and FE Curie temperature are obtained through optimized quenching rate and temperature. Quenching effect on piezoelectricity is especially significant for the samples near morphotropic phase boundaries (MPB), which can be ascribed to quenching-induced changes in phase ratio (rhombohedral and tetragonal phase) and domain structure/defect dipole orientation. Moreover, a new poling method, that is, cooling the sample at a constant dc current across FE T_C, is established to improve the piezoelectricity. This work not only reveals the possible mechanism of quenching effect on the improved piezoelectricity in the BFO-based piezoceramics (especially near the MPB) but also suggests an electric current poling strategy for improving piezoelectricity by suppressing the defect dipole effects in BFO-based and even other piezoelectrics.