Piezoelectric and ferroelectric properties of Bi-compensated (Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3 lead-free piezoelectric ceramics

(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3 (BNT-BKT) ceramics as a promising candidate for lead-free piezoelectric ceramics were studied with a special emphasis on the compositional dependence of piezoelectric and ferroelectric properties. One mole percent excess Bi was added to compensate for the volatilization of Bi3+ ions during sintering, which was found to be effective in improving the piezoelectric properties of the resultant BNT-BKT ceramics. The piezoelectric, ferroelectric, and dielectric properties of the Bi-compensated BNT-BKT ceramics were investigated and discussed in relation to the morphotropic phase boundary that is close to the composition range of 20-24 mol % BKT. The maximum piezoelectric constant d(33) (207 pC/N) and electromechanical coupling factor k(p) (35%) were obtained at the compositions of 23% and 20%, respectively. (C) 2008 American Institute of Physics.