Piezoelectric and dielectric properties of lead-free piezoelectric ceramics in NBT-Ba (NbO3)2 binary system

A new (Na1/2Bi1/2) TiO3-based lead-free piezoelectric ceramics of (1-x) (Na1/2Bi1/2) TiO3-xBa (NbO3)2 (x = 0-1.4%) were prepared by the conventional ceramic sintering technique. X-ray diffraction patterns indicate that the ceramics studied can form pure perovskite structure and SEM observation indicate that doping with a moderate amount of Ba (NbO3)2 can promote the precipitation of stick grains. The dielectric constants as a function of temperature at different frequencies show obvious relaxor characteristic. The relaxor characteristic becomes more obvious with the increasing of the content of Ba (NbO3)2. It is found that the piezoelectric constant d33 and planar electromechanical coupling factor kp increase first and then decrease with the increase of x value. The favourable properties of d33 and kp are 94 pC/N and 0.171 were obtained when the Ba (NbO3)2 content was 0.6%. The dielectric loss tan d increase with the increasing of x value.