Comparative study on structure, dielectric, and piezoelectric properties of (Na0.47Bi0.47Ba0.06)0.95A0.05TiO3 (A = Ca2+/Sr2+) ceramics: Effect of radii of A-site cations

Lead-free ceramics (Na0.47Bi0.47Ba0.06)TiO3, (Na0.47Bi0.47Ba0.06)0.95Ca0.05TiO3, and (Na0.47Bi0.47Ba0.06)0.95Sr0.05TiO3 (BNBT, BNBT-Ca, and BNBT-Sr, respectively) were obtained via solid-state sintering. Due to the different radii between Ca2+ and Sr2+, the mean radii of the A-site cations in BNBT-Ca, BNBT, and BNBT-Sr are different. Effects of radii of the A-site cations on crystallite structure, microstructure, piezoelectric, and dielectric properties of the ceramics were investigated comparatively. X-ray diffraction and Raman spectroscopy results reveal the lattice distortion due to the doping. With the increase in the mean radii of the A-site cations, lattice parameters, tolerance factor, band-gap energy, average size of grains, dielectric constant, and piezoelectric constant of the ceramics increase. The results imply that structure and electrical properties of BNBT-based ceramics are associated with radii of the A-site cations, which provides a possible route to tune structure and electrical properties of BNBT-based materials by changing radii of the A-site cations.