Ferroelectric and piezoelectric properties of (Bi1/2K1/2)TiO3 ceramics

The dielectric, ferroelectric and piezoelectric properties of bismuth potassium titanate, (Bi1/2K1/2)TiO3 (BKT), ceramics were studied. Single-phase BKT ceramics with a high relative density of 97% were obtained by the hot pressing (HP) method. The resistivities of BKT ceramics hot-pressed at 1060 and 1080 degrees C (hereafter abbreviated as BKT-HP1060 degrees C and BKT-HP1080 degrees C) were fairly high being of the order of 10(13) Omega.cm at room temperature (RT). The Curie temperature T-c of BKT-HP1060 degrees C was 437 degrees C, which is relatively higher than those of other lead-free piezoelectric materials. In this study, the ferroelectric properties of BKT ceramics were successfully obtained with fully saturated hysteresis loops. The remanent polarization P-r and coercive field E-c of BKT-HP1080 degrees C were 22.2 mu C/cm(2) and 52.5kV/cm, respectively. D-E hysteresis loops for these ceramics were observed even at 260 degrees C. The electromechanical coupling factor k(33) and piezoelectric constant d(33) of BKT-HP1080 degrees C were 0.28 and 69.8pC/N, respectively. The second-phase transition temperature T-2 of 340 degrees C was determined from the temperature dependence of piezoelectric and dielectric measurements.