Effect of KNbO3 addition on diffuse phase transition and dielectric properties of Bi0.5Na0.5TiO3 ceramics

Lead-free (1-x)Bi0.5Na0.5TiO3 – xKNbO3 (BNT-KN) ceramics where x = 0.00, 0.05, 0.10 and 0.15 were carried out by the modified two-step mixed oxide method. The effects of KNbO3 on phase transition and dielectric properties were systematically investigated. The dielectric property investigation indicated that the degree of the diffuse phase transition behavior increased with KNbO3 addition. Phase transition of rhombohedral to pseudocubic structure was dependent on the amount of KNbO3 contained. The dielectric constant of the KNbO3 added Bi0.5Na0.5TiO3 ceramic was enhanced by KNbO3 addition. The maximum dielectric constant is obtained at the composition of x = 0.05. KN addition could enhance the piezoelectric response. The d33 of x = 0.05 sample reached as high as 130 pC/N.