Piezoelectric and ferroelectric properties of lead-free [Bi1−y(Na1−x−yLix)]0.5BayTiO3 ceramics

Lead-free [Bi1−y(Na1−x−yLix)]0.5BayTiO3 (BNLB-x/y) piezoelectric ceramics were prepared by sintering the constituent oxides, and their piezoelectric and ferroelectric properties studied. The results of X-ray diffraction (XRD) suggest that Li+ and Ba2+ diffuse into the Bi0.5Na0.5TiO3 (BNT) lattices to form a solid solution with a single-phase perovskite structure. The ceramics can be well sintered at 1100–1150 °C. The introduction of Li+ and Ba2+ into Bi0.5Na0.5TiO3 significantly decreases the coercive field, Ec but maintains the large remanent polarization, Pr of the materials. The ceramics exhibit relatively good piezoelectric properties and very strong ferroelectricity: piezoelectric constant, d33 = 208 pC/N, planar electromechanical coupling factor, kp = 37.0%, remanent polarization, Pr = 38.5 μC/cm2, coercive field, Ec = 3.27 kV/mm. The depolarization temperature, Td of BNLB-0.075/0.04 ceramics is about 190 °C.