High-performance Bi0.5Na0.5TiO3 single crystals grown by high-oxygen-pressure flux method

High-Po-2 (oxygen pressure) crystal growth is developed for Bi0.5Na0.5TiO3 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 suface reaction (oxygen desorption), which is suppressed at a higher Po-2, Bi0.5Na0.5TiO3 crystal grown at a Po-2 of 1 MPa exhihit a satureated remanent polarization of 44 mu C/cm(2) along [110](cubic), suggesting a spontaneous polarization of 54 mu C/cm(2) along [111](cubic) (polar direction) of rhombohedral Bi0.5Na0.5TiO3. High-Po-2 heat treatments are proposed to be effective for fabricating high-quality and high-performance ferroelectric/piezoelectric devices using Bi-based ferroelectric oxides.