Polarization and Piezoelectric Properties of High Performance Bismuth Sodium Titanate Single Crystals Grown by High-Oxygen-Pressure Flux Method

(Bi 0.5 Na 0.5 )TiO 3 (BNT) single crystals were grown by flux method at a high oxygen pressure ( P O 2 ) of 1 MPa, and their polarization and piezoelectric properties were investigated. BNT single crystals exhibited a saturated polarization hysteresis with remanent polarizations ( P r ) of 31 µC/cm 2 along [100] c , 44 µC/cm 2 along [110] c and 54 µC/cm 2 along [111] c . These results show that spontaneous polarization of BNT is approximately 55 µC/cm 2 or larger. Strain measurements of rhombohedral BNT crystals suggest that the polarization reversal along [111] c is achieved by non-180° P s rotation whereas that along [100] c is accomplished by 180° P s switching.