Processing and Electromechanical Properties of (Bi_0.5Na_0.5)_(1?1.5x)La_xTiO₃Ceramics

Bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) with 0–6 at.% lanthanum was prepared by the conventional mixed oxide method. Each composition was calcined at 800–900°C for 2–5 h to form a pure perovskite phase. Green pellets were sintered at 1050–1150°C for 1–4 h to obtain dense ceramics with at least 95% of theoretical density. X–ray diffraction (XRD) showed phase distortion as lanthanum was added to this system. Meanwhile, a small amount of La was found to affect the grain size and had an influence on the poling conditions and electrical properties. The BNT–based composition with 1 at.% La doping provided a dielectric constant (K) of 560, a piezoelectric charge constant (d33) of 92 pC/N, and a hydrostatic piezoelectric coefficient (dh) of 72 pC/N.