Enhanced energy-storage performance with excellent stability under low electric fields in BNT-ST relaxor ferroelectric ceramics

Relaxor ferroelectrics are promising candidates for pulsed power dielectric capacitor applications because of their excellent energy-storage properties. Different from most relaxor ferroelectrics whose energy-storage density was improved by increasing the breakdown strength and reducing the remanent polarization, in this study, anti-ferroelectric (AFE) AgNbO ₃ (AN) was used to partially substitute the relaxor ferroelectric 0.76Bi _0.5 Na _0.5 TiO ₃ -0.24SrTiO ₃ (BNT-ST) of morphotropic phase boundary (MPB) composition to reduce the remanent polarization while maintaining large maximum polarization. In this way, a large recoverable energy-storage density (2.03 J cm ^-3 ) was obtained in the BNT-ST-5AN ceramics under lower electric field of 120 kV cm ^-1 , which is superior to other lead-free energy-storage materials under similar electric fields. Moreover, excellent temperature (25-175 °C) and frequency (1-100 Hz) stabilities are achieved. This performance demonstrates that the BNT-ST-5AN ceramics form a promising class of dielectric capacitive material for high-temperature pulsed power capacitors with large energy-storage density.