Outstanding energy storage properties under moderate electric field in BiMg2/3Nb1/3O3-modified NaNbO3-based relaxor ceramics

NaNbO 3 (NN)-based ceramics have received a great deal of attention for the potential application in dielectric energy storage capacitors. However, the energy storage properties (ESP) remain low, particularly under moderate electric field. Herein, a Bi-rich doping unit of BiMg 2/3 Nb 1/3 O 3 (BMN) was introduced into a 0.85NaNbO 3 -0.15Bi 0.1 Sr 0.85 TiO 3 (NN-SBT) matrix, aiming to improve polarization along ESP. As a result, a large recoverable energy density ( W rec ) of ∼6.1 J/cm 3 and an efficiency ( η ) of ∼81 % were achieved in NN-SBT-0.08BMN ceramics under a moderate electric field of 337 kV/cm. The improved ESP can be attributed to the introduction of BMN, which delays the polarization saturation of NN-SBT ceramics, while maintaining the maximum polarization (∼43.6 μC/cm 2 ), and generating polar nanoregions (PNRs). Moreover, the optimal ceramics exhibited good thermal (25–130 °C) and frequency (1–300 Hz) stabilities, and fatigue endurance (>10 5 cycles). These results illustrate that the designed NN-SBT-0.08BMN ceramics are promising for application in dielectric energy storage capacitors with high ESP under a moderate electric field.