BNBT-CTa ceramics: moderate electric fields yield high energy storage and thermal stability

The combination of high power density, fast charging–discharging speeds, and environmental friendliness positions lead-free ceramic-based dielectric capacitors as a leading candidate material for next-generation pulsed power devices. However, to achieve a high recoverable energy density, a relatively large external electric field needs to be applied, which compromises the electrical insulation integrity and stymies the future development of ceramic capacitors. Under the guidance of various cooperative strategies, this study successfully prepared (1 −  x )[0.94(Bi 0.5 Na 0.5 )TiO 3 – 0.06BaTiO 3 ]– x Ca 0.5 TaO 3 ceramics, discussing the influence of the linear dielectric Ca 0.5 TiO 3 in BNBT ceramics. The paper has found that increasing the content of CTa can enhance the density of BNBT ceramics and reduce the grain size. When x  = 0.12, a grain size of 0.70 μm is obtained, and the breakdown electric field increases from 250 kV/cm at x  = 0.01 to 454 kV/cm at x  = 0.12. Meanwhile, a likewise considerable recoverable energy storage density is achieved, exceeding 7.19 J/cm 3 under moderate electric fields and achieving an outstanding energy storage efficiency ( η ) of 78%, which can be suitable for advanced energy storage capacitors that operate under medium electric fields.