Growth and characterization of Na0.5Bi0.5TiO3-BaTiO3 lead-free piezoelectric crystal by the TSSG method

In this paper, polycrystalline material of 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (abbreviated as NBBT94/6) was synthesized by solid-state reaction techniques. DTA and TG analysis indicate the proper temperature for solid-state reaction is 1200 deg C. A single crystal with dimensions of 25 mm X 10 mm was successfully grown by using the top-seeded solution growth (TSSG) method. X-ray fluorescence analysis revealed that the composition of the as-grown crystal is NBBT98/2. X-ray powder diffraction results show that the as-grown NBBT98/2 crystal possesses the perovskite structure and belongs to the rhombohedral system. The unit-cell constants of the as-grown NBBT98/2 crystal are a = b = c = 3.8862 A and = beta = gamma = 89.2 deg . At room temperature, the dielectric constant of < 0 0 1 > oriented NBBT98/2 crystal is 770 at 10 kHz and it decreases to 430 after poling under the E-field of 7 kV/mm. Maximum d33 values of 60, 65 and 30 pC/N were obtained for < 0 0 1 > , < 1 1 0 > and < 1 1 1 > oriented NBBT98/2 crystal, respectively.