ABSTRACT: The ferroelectric and piezoelectric properties of (1−x)Bi0.5(Na0.8-K0.2)0.5TiO3-xBaZn0.5W0.5O3 ((1−x)BNKT-xBZW) ceramics have been studied to clarify the temperature dependence of the polarization-electric field (P-E) hysteresis and dielectric properties. Based on the temperature dependence of the dielectric constant, it was found that the depolarization temperature (Td) shifted to lower temperatures, depending on the composition x. The crystal structure refinement of (1−x)BNKT-xBZW ceramics with rhombohedral and tetragonal phases revealed that the fraction of tetragonal phase to rhombohedral phase increased in the composition range of 0-0.05, which implies a formation of a morphotropic phase boundary (MPB). The piezoelectric constant (d33) of the (1−x)BNKT-xBZW ceramics increased with the composition x up to x = 0.05 and the maximum value was 168 pC/N. Such an increase in d33 is attributed to the increase in the dielectric constant at room temperature which is due to the shift of Td
a pinched P-E hysteresis loop was obtained at x = 0.05. The temperature dependence of the P-E hysteresis loops indicated that the shape of the hysteresis loop is closely related to the coexistence of ferroelectric and antiferroelectric phases.