Bi0.5Na0.5TiO3-based ceramics with large energy density and high efficiency under low electric field

Relaxor ferroelectrics with high energy storage performance are urgently expected for energy storage capacitors. In this study, a large recoverable energy density with high efficiency was achieved in Sr_0.7Bi_0.2TiO₃ (SBT)-modified Bi_0.5Na_0.5TiO₃ (BNT) ceramics via a conventional solid-state reaction process. The Sr²⁺ and Sr²⁺ vacancies can be simultaneously introduce into (1−x)BNT−xSBT ceramics after doping SBT, which is conducive to suppress the presence of oxygen vacancies, inhibit grain growth, facilitate the generation of dynamic polar nanoregions (PNRs) and improve the relaxation. As a result, a large recoverable energy density of 1.81 J/cm³ with prominent efficiencies of 85% under a low electric field of 130 kV/cm was achieved at x = 0.4. The results demonstrate that 0.6BNT–0.4SBT ceramic is expected to be a promising candidate for energy storage capacitor applications. This work proposes a design idea to obtain excellent energy storage properties at low electric fields in BNT-based ceramics via composition design and A-site defect engineering.