High-Performance Bi0.5Na0.5TiO3 Single Crystals Grown by High-Oxygen-Pressure Flux Method

High- P O 2 (oxygen pressure) crystal growth is developed for Bi 0.5 Na 0.5 TiO 3 single crystals based on defect chemistry at high temperatures. Thermogravimetric analysis shows that the vacancy formations of Bi and O at high temperatures are controlled by the surface reaction (oxygen desorption), which is suppressed at a higher P O 2 . Bi 0.5 Na 0.5 TiO 3 crystals grown at a P O 2 of 1 MPa exhibit a saturated remanent polarization of 44 µC/cm 2 along [110] cubic , suggesting a spontaneous polarization of 54 µC/cm 2 along [111] cubic (polar direction) of rhombohedral Bi 0.5 Na 0.5 TiO 3 . High- P O 2 heat treatments are proposed to be effective for fabricating high-quality and high-performance ferroelectric/piezoelectric devices using Bi-based ferroelectric oxides.