Remarkably enhanced dielectric stability and energy storage properties in BNT-BST relaxor ceramics by A-site defect engineering for pulsed power applications

Lead-free bulk ceramics for advanced pulsed power capacitors show relatively low recoverable energy storage density (W-rec) especially at low electric field condition. To address this challenge, we propose an A-site defect engineering to optimize the electric polarization behavior by disrupting the orderly arrangement of A-site ions, in which Ba0.105Na0.325Sr0.245-1.5x rectangle 0.5xBi0.325+xTiO3 (BNS0.245-1.5x rectangle 0.5xB0.325+xT, x = 0, 0.02, 0.04, 0.06, and 0.08) lead-free ceramics are selected as the representative. The BNS0.245-1.5x rectangle 0.5xB0.325+xT ceramics are prepared by using pressureless solid-state sintering and achieve large W-rec (1.8 J/cm(3)) at a low electric field (@110 kV/cm) when x = 0.06. The value of 1.8 J/cm(3) is super high as compared to all other W-rec in lead-free bulk ceramics under a relatively low electric field (< 160 kV/cm). Furthermore, a high dielectric constant of 2930 within 15% fluctuation in a wide temperature range of 40-350 V is also obtained in BNS0.245-1.5x rectangle 0.5xB0.325+xT (x = 0.06) ceramics. The excellent performances can be attributed to the A-site defect engineering, which can reduce remnant polarization (P-r) and improve the thermal evolution of polar nanoregions (PNRs). This work confirms that the BNS0.245-1.5x rectangle 0.5xB0.325+xT (x = 0.06) ceramics are desirable for advanced pulsed power capacitors, and will push the development of a series of Bi0.5Na0.5TiO3 (BNT)-based ceramics with high W-rec and high-temperature stability.

Automated summary

Lead-free ceramics with A-site defect engineering exhibit large energy storage density and high dielectric constant, which are significant for the development of advanced pulsed power capacitors.