Enhanced polarization switching in ferroelectric Bi0.5Na0.5TiO3 single crystals by defect control



Single crystals of ferroelectric (Bi,Na)TiO3 (BNT) were grown by the top-seeded solution growth (TSSG) method at a high oxygen pressure of 0.9 MPa using Pt crucibles and their conductivity (leakage current) and polarization properties were investigated at 25 °C along 〈100〉cubic. The platinum concentration ([Pt]) in BNT crystals was controlled by using different kinds of Na salts in flux. It is shown that the conductivity of BNT crystals is governed by Bi vacancies for crystals with a [Pt] less than approximately 4000 ppm and by Pt impurities for ones with a higher [Pt].

original image

Photo and polarization hysteresis of a high-quality (Bi,Na)TiO3 ferroelectric single crystal. Enhanced polarization switching (a large remanent polarization and a low coercive field) was achieved by defect control during the crystal growth.