Enhanced energy storage performance and thermal stability in relaxor ferroelectric BNKT-BBN solid solution ceramics

Bi_0.5Na_0.5TiO₃ (BNT)-based relaxor ferroelectrics have attracted considerable interest over the past decades as candidate materials to replace lead-based piezoelectrics because of their environmental friendliness. Moreover, owing to their high maximum polarization and high-power density resulting from their relaxor activity, BNT-based relaxor ferroelectrics have attracted attention as potential candidates for energy storage. Herein, bismuth layer-structured BaBi₂Nb₂O₉ (BBN) was introduced into the perovskite binary material system 0.78(Bi_0.5Na_0.5TiO₃)-0.22(Bi_0.5K_0.5TiO₃) (BNKT). Compared to pure BNKT ceramics, BNKT-BBN exhibited improved relaxor behavior and suppressed grain growth. Moreover, an increase in BBN content increased the breakdown strength. Consequently, the energy storage efficiency increased from 32 % to 58 %. In addition, the thermal stability (ΔW_rec/W_rec) remained below ∼5 % in the temperature range from room temperature to 200 °C. The findings of this study demonstrated that the introduction of BBN into BNT-based relaxor ferroelectrics is an effective way to improve energy storage performance and high temperature stability.