Papers by Keyword: Depolarization Temperature

Abstract: Lead-free 0.85(Bi1/2Na1/2)TiO3- 0.10(Bi1/2K1/2)TiO3- 0.05BaTiO3 (BNKB) ceramics with Li2CO3 or (Bi1/2Li1/2)TiO3 (BLT) added were fabricated by a conventional solid oxide route. The XRD analysis indicates that Li2CO3 introduction leads to the increasing of fraction of tetragonal phase while the BLT introduction does in a reverse tendency. Meanwhile, the depolarization temperature Td of Li2CO3-added BNKB ceramics was enhanced obviously while that of BLT-added BNKB ceramics went down as the addition amount increased. The similarity in variation of the phase structure and the Td of BNKB ceramics reveals the nature of Li+ introduction source on phase structure in BNKB ceramics.

Abstract: The phase transition temperatures of divalent and trivalent ions substituted (Bi1/2Na1/2)TiO3 ceramics were investigated in detail by electrical measurement. BNT ceramics substituted by divalent (Ca2+, Sr2+ and Ba2+) and trivalent (La3+, Nd3+, Ho3+ and Yb3+) ions were prepared by conventional ceramic fabrication process. For these ceramics, the depolarization temperature, Td, the rhombohedral-tetragonal phase transition temperature, TR-T, and the temperature of the maximum dielectric constant, Tm, were determined on the basis of the temperature dependences of dielectric and piezoelectric properties. In this study, we demonstrated the relationship between phase transition temperature and ionic radius of ions substituted in the A-site of BNT 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.