The effects of sintering atmosphere on microstructures and electrical properties of lead-free (Bi0.5Na0.5)TiO3-based ceramics

0.93(Bi0.5Na0.5)TiO3–0.07BaTiO3 (BNT–7BT) piezoelectric ceramics sintered in O2 and N2 have been investigated to understand the effects of sintering atmosphere in defects, microstructures, and dielectric properties. The BNT–7BT ceramics sintered in O2 and N2 exhibit a major pseudo-cubic structure with slight distortion from the cubic cell. The specimen sintered in N2 atmosphere shows larger grain sizes than the specimen sintered in O2. The X-ray photoelectron spectroscopy (XPS), SEM–EDS, and TEM–EDS suggest that specimen sintered in N2 atmosphere exhibits more ion vacancies. Leakage current measurements suggest more oxygen vacancies for specimen sintered in N2. A higher remnant polarization and lower coercive field were observed for specimen sintered in O2. Strain vs. E field (S–E) loops display higher E-field induced strain up to 0.256% and higher dielectric permittivity for specimen sintered in O2. This work suggests that sintering in the O-rich atmosphere can reduce defects and enhances ferroelectric, dielectric, and piezoelectric properties.