and it has rhombohedral symmetry [3], [4] and [5]. However, BNT ceramics do not readily exhibit very strong piezoelectric property because of difficulty to polarize the material, due to its large coercive field (Ec=73 kV/cm) [6]. To improve the piezoelectric property, BNT-based solid solutions formed with many other pervskite materials such as BaTiO3(BT) [7], Bi0.5K0.5TiO3(BKT) [8], NaNbO3(NN) [9], Bi(Zn0.5Ti0.5)O3(BZT) [10] and Bi(Mg0.5Ti0.5)O3(BMT) [11] have been developed. In particular, BNT–BKT–BT in the vicinity of morphotropic phase boundary has been developed by many researchers