Improvements in piezoelectric and energy harvesting properties with a slight change in depolarization temperature in modified BNKT ceramics by a simple technique

Abstract

For many BNT-based ceramics, an attempt to increase the piezoelectric properties usually results in a decrease in depolarization temperature (T_d). This trend limits the applications of the materials. Many previous experiments have used different methods to enhance the piezoelectric properties and improve the T_d characteristic. In this study, we demonstrated a simple technique (thermal annealing) to enhance the piezoelectric properties with a very slight decrease in T_d by ∼2 °C for a modified BNKT ceramic (BNKT doped with ZnO). Other phase transition characteristic temperatures of the studied ceramics were also slightly changed. The optimum dielectric (ε_r = 651, tan δ = 0.0503, T_F–R = 167.38 °C, T_m = 305.41 °C, ε_max = 5551, T_B = 367.15 °C, T_d = 155.98 °C, and γ = 1.43), ferroelectric (P_max = 41.28 μC cm⁻², P_r = 35.85 μC cm⁻², E_c = 42.60 kV cm⁻¹ and R_sq = 1.42), piezoelectric (d₃₃ = 198 pC N⁻¹, k_p = 0.598, and g₃₃ = 34.35 × 10⁻³ Vm N⁻¹), and energy harvesting (FoM = 6.80 pm² N⁻¹) were obtained for the 8 h annealed ceramic. Furthermore, higher energy harvesting properties (which were 32% higher than that of the unannealed ceramic) were obtained after employing this technique.