Crystal growth and high piezoelectric performance of 0.95Na0.5Bi0.5TiO3–0.05BaTiO3 lead-free ferroelectric materials

A large single crystal of 0.95Na0.5Bi0.5TiO3?0.05BaTiO3 (0.95NBT?0.05BT) with dimensions of 35?mm diameter ? 10?mm length was grown by the top-seeded-solution growth method (TSSG). X-ray powder diffraction results indicate that the as-grown 0.95NBT?0.05BT crystal is of a perovskite structure and belongs to the rhombohedral system. The dielectric, ferroelectric and piezoelectric properties were investigated in detail. The room temperature dielectric constants for unpoled 0?0?1, 1?1?0 and 1?1?1 oriented crystal samples are 1450, 1650 and 1750 at 1?kHz and decrease to 1050, 800 and 480 after poling. The remanent polarizations Pr of 0?0?1, 1?1?0 and 1?1?1 oriented crystal samples are 16.44??C?cm?2, 23.69??C?cm?2 and 27.63??C?cm?2 with the coercive fields Ec of 32.72?kV?cm?1, 31.20?kV?cm?1 and 28.15?kV?cm?1, respectively. Interestingly, the piezoelectric constant d33 of the 0.95NBT?0.05BT crystal shows apparent anisotropy along its pseudocubic 0?0?1, 1?1?0 and 1?1?1 directions. The 0?0?1 poled 0.95NBT?0.05BT crystals show excellent piezoelectric properties with d33 = 280?pC?N?1. However, the d33 values of the 1?1?1 oriented 0.95NBT?0.05BT crystal are only 90?pC?N?1. The origin of apparent anisotropy in piezoelectric properties has been discussed in detail.