Structure and electrical behavior of unpoled and poled 0.97(Bi0.5Na0.5)0.94Ba0.06TiO3-0.03BiAlO3 ceramics

The ceramics (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT) and 0.97BNBT-0.03BiAlO3 (BNBTA/0.03) were synthesized via a solid-state reaction method. Effects of electric poling and Al3+-doping on structure and electrical behavior of BNBT and BNBTA/0.03 were studied. The results of Raman spectroscopy and X-ray diffraction confirm lattice distortion due to the doping of Al3+. BNBT and BNBTA/0.03 exhibit pure phase and dense microstructures. The tetragonal-rhombohedral morphotropic phase boundary exists in both samples. Electric poling causes an increase in the amount of the tetragonal phase. Dielectric behavior is sensitive to the electric poling and Al3+-doping. Compared to BNBT, BNBTA/0.03 exhibits pinched polarization loops, current-electric field curves with four peaks, and higher normalized piezoelectric constant. Based on the results of ultraviolet-visible diffuse reflectance spectra, electric conductivity, and Rayleigh analysis, it is suggested that the differences in electrical behavior between BNBT and BNBTA/0.03 are related to oxygen vacancies.