Enhanced Piezoelectric Properties of Tetragonal (Bi1/2K1/2)TiO3 Lead-Free Ceramics by Substitution of Pure Bi-Based Bi(Mg2/3Nb1/3)O3.

Crystal structure, piezoelectric, and dielectric properties were investigated in the new lead-free BKT-based piezoelectric ceramics of (1− x)( Bi1/2 K1/2) TiO3- x Bi( Mg2/3 Nb1/3) O3. The morphotropic phase boundary (MPB) of the system between tetragonal and rhombohedral phases lies near the composition of x = 0.02. The optimal piezoelectric property of small-signal d33 is much enhanced to be 96 pC/N ( x = 0.01), which is higher than any other BKT-based compositions. By the introduction of Bi( Mg2/3 Nb1/3) O3, the ceramics exhibit a lower coercive field EC. In addition, a relaxor-like behavior with a frequency-dependent Curie temperature Tm is observed, and high Curie temperature Tm around 380°C is obtained in the investigated system. This study suggests that the piezoelectric properties of BKT can be significantly improved by the means of Bi( Mg2/3 Nb1/3) O3 substitution. [ABSTRACT FROM AUTHOR]