Ferroelectric and piezoelectric properties of (Bi_1/2K_1/2)(Zr_xTi_{1− x})O₃ lead-free ceramics

We report the effect of Zr substitution for Ti on the ferroelectric and piezoelectric properties of lead-free (Bi_1/2K_1/2)TiO₃ (BKT) ceramics. Dense ceramics of (Bi_1/2K_1/2)(Zr_xTi_{1− x})O₃ with x up to 0.06 were fabricated by sintering of hydrothermally derived fine powders. The investigation of the crystal structure and dielectric properties revealed that the Zr substitution decreased the tetragonal lattice distortion of BKT and stabilized the relaxor state. The coercive electric field was found to be decreased monotonically with increasing the Zr content, while the largest remanent polarization of 26 μC cm⁻² was observed at x = 0.04. As a result, the ceramic with x = 0.04 showed an enhanced piezoelectric d₃₃ constant of 140 pC N⁻¹.