Structure and electrical properties of Nd2O3-doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 ceramics

Nd2O3 doped 0.82Bi0.5Na0.5TiO3–0.18Bi0.5K0.5TiO3 (abbreviated to BNKT) binary lead-free piezoelectric ceramics were synthesized by the conventional mixed-oxide method. The results show that the BNKT ceramics with 0–0.15 wt.% Nd2O3 doping possesses a single perovskite phase with rhombohedral structure. The grain size of BNKT decreased with the addition of Nd2O3 dopant. The temperature dependence of the dielectric constant ɛr revealed that there were two-phase transitions from ferroelectric to anti-ferroelectric and anti-ferroelectric to paraelectric. A diffuse character was proved by linear fitting of the modified Curie–Weiss law. At room temperature, the specimens containing 0.0125 wt.% Nd2O3 with homogeneous microstructure presented excellent electrical properties: the piezoelectric constant d33 = 134 pC/N, the electromechanical coupling factor Kp = 0.27, and the dielectric constant ɛr = 925 (1 kHz).