Effect of preparation method on properties of BNT-BKT-BT piezoelectric ceramics

0.852Bi_0.5Na_0.5TiO₃-0.120Bi_0.5K_0.5TiO₃-0.028BaTiO₃(BNT-BKT-BT) ceramics prepared by solid state reaction and hydrothermal method is investigated in this paper. The study is aimed at finding out the effects of different preparation methods on dielectric and piezoelecrtic properties of BNT-BKT-BT ceramics. BNT-BKT-BT ceramics were fabricated by conventional solid state reaction and hydrothermal method. XRD results show that a pure perovskite without a secondary phase is structured, while the diffraction intensity of the powder by solid state reaction is higher than that of the powder by hydrothermal method. At the same time, SEM shows a significant difference of surface topography between the ceramics comes up with different preparation methods, which also takes place in dielectric and piezoelectric properties of the ceramics. The values of piezoelectric constant d₃₃, dielectric constant ε_r, mechanical quality factor Q_m, and electromechanical planar coupling coefficients k_p of BNT-BKT-BT ceramics by solid state reaction are higher than that of ceramics by hydrothermal method while the dielectric loss factor tanδ and thick electromechanical coupling factor k_t is lower. The experimental results reveal that the preparation method is of great help in taking effect on dielectric constant ε_r, and piezoelectric constant d₃₃.