The effect of SZ substitution on BNKT ceramics was investigated
in terms of crystal structure, field-induced strain, ferroelectric and
dielectric properties to explore good lead-free materials for actuator
applications. Encouraging results of field-induced unipolar
strain (0.37%) corresponding to a normalized strain (Smax/
Emax ¼ 617 pm/V) was realized at room temperature for BNKTeSZ3
ceramics. This high field-induced strain response of BNKTeSZ3 may
be possibly due to the coexistence of highly competitive free energy
between ferroelectric and ferroelectric relaxor phases. The piezoelectric
coefficient d33 increased from 150 pC/N for pure BNKT to
190 pC/N for BNKTeSZ2. The dielectric curves of BNKTeSZ100x
ceramics show that the diffuse character around Td and Tm increases
with increasing SZ content, which implies the characteristics
of relaxor ferroelectrics.