Nonergodic–ergodic relaxor transition and enhanced piezoelectric properties in B-site complex ions substitution 0.93Bi0.5Na0.5TiO3–0.07BaTiO3 ceramics

The influence of B-site complex ions substitution on the dielectric and piezoelectric properties of (Bi0.5Na0.5)0.93Ba0.07Ti1–x(W0.5Mg0.5)xO3 (BNBT–xWM) ceramics was studied in detail. X-ray diffraction patterns revealed that B-site substitution resulted in a phase transition from the tetragonal phase to pseudocubic phase. Ferroelectric to relaxor (FE-RE) phase transition temperature TF-R decreased with increasing (W0.5M0.5)4+ dopants, finally below room temperature. The destabilization temperature of piezoelectric constant d33, together with ferroelectric response was decreased with increasing x. However, the strains could be significantly enhanced with the addictive of (W0.5M0.5)4+, and a large strain of 0.325% with a normalized strain, d33* of 541.7 pm/V could be achieved for x = 0.04 ceramics [ergodic relaxor (ER) dominant]. The enhanced strains might attribute to the composition-induced NR–ER transition and high dynamic polar-nanoregions (PNRs), which strongly affecting piezoelectric and dielectric properties.