Piezoelectric Properties and Depolarization Temperatures of (Bi<sub>1/2</sub>Na<sub>1/2</sub>)TiO<sub>3</sub>-(Bi<sub>1/2</sub>K<sub>1/2</sub>)TiO<sub>3</sub>-BaTiO<sub>3</sub> Lead-Free Piezoelectric Ceramics

Abstract

The piezoelectric properties of a solid solution based on the three components of bismuth sodium titanate, (Bi1/2Na1/2)TiO3 (BNT), bismuth potassium titanate, (Bi1/2K1/2)TiO3 (BKT), and barium titanate, BaTiO3 (BT), that is, x(Bi1/2Na1/2)TiO3-y(Bi1/2K1/2)TiO3-zBaTiO3 [BNBKy:z(x); x+y+z=1] are investigated. Fine piezoelectric properties in lead-free piezoelectric ceramics were obtained near the MPB composition, and the highest electromechanical coupling factors, k33 and kp, and piezoelectric constant, d33, were 0.58 and 0.36 for BNBK2:1(0.89) and 181 pC/N for BNBK2:1(0.88), respectively. In this study, we also measured the depolarization temperature, Td, from the temperature dependence of dielectric and piezoelectric properties.