Piezoelectric and dielectric characteristics of lead-free BNKLBT ceramic thick film and multilayered piezoelectric actuators

Lead-free piezoelectric 0.885(Bi_0.5Na_0.5)TiO₃–0.05(Bi_0.5K_0.5)TiO₃–0.015(Bi_0.5Li_0.5)TiO₃ 0.05BaTiO₃ ceramics (abbreviated as BNKLBT-1.5) were prepared by a conventional mixed oxide method. The composition has a piezoelectric d₃₃ constant of 154 × 10⁻¹² C/N, an electromechanical coupling coefficient k_t of 0.519, a relatively low dissipation factor (tan δ = 1.6%) at 1 kHz. BNKLBT-1.5 multilayered actuators have been fabricated using a roll-casting technique. Each single layer has dimensions of 9.0 mm × 9.0 mm × 0.2 mm. Four multilayer actuators with 5, 10, 15 and 20 layers have been fabricated. Their capacitance and displacement under an a.c. field were measured. The capacitance measured at 1 kHz is 9.64 nF, 14.69 nF, 25.36 nF, 32.59 nF and the displacement measured at 5 kHz is 867 pm/V, 1331 pm/V, 2060 pm/V, 2442 pm/V, respectively.