Ferroelectric and Piezoelectric Properties of (Bi_1/2K_1/2)TiO₃ Ceramics

Abstract

The dielectric, ferroelectric and piezoelectric properties of bismuth potassium titanate, (Bi 1/2 K 1/2 )TiO 3 (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°C (hereafter abbreviated as BKT-HP1060°C and BKT-HP1080°C) were fairly high being of the order of 10 13 Ω·cm at room temperature (RT). The Curie temperature T c of BKT-HP1060°C was 437°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°C were 22.2 µC/cm 2 and 52.5 kV/cm, respectively. D – E hysteresis loops for these ceramics were observed even at 260°C. The electromechanical coupling factor k 33 and piezoelectric constant d 33 of BKT-HP1080°C were 0.28 and 69.8 pC/N, respectively. The second-phase transition temperature T 2 of 340°C was determined from the temperature dependence of piezoelectric and dielectric measurements.