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 (d ₃₃ = 198 pC N^-1, k _p = 0.598, and g ₃₃ = 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.