Enhanced Energy Storage Performance in Na 0.5 Bi 0.5 TiO 3 -Based Relaxor Ferroelectric Ceramics via Compositional Tailoring.

Owing to the high power density, excellent operational stability and fast charge/discharge rate, and environmental friendliness, the lead-free Na 0.5 Bi 0.5 TiO 3 (NBT)-based relaxor ferroelectrics exhibit great potential in pulsed power capacitors. Herein, novel lead-free (1-x)(0.7Na 0.5 Bi 0.5 TiO 3 -0.3Sr 0.7 Bi 0.2 TiO 3 )-xBi(Mg 0.5 Zr 0.5 )O 3 (NBT-SBT-xBMZ) relaxor ferroelectric ceramics were successfully fabricated using a solid-state reaction method and designed via compositional tailoring. The microstructure, dielectric properties, ferroelectric properties, and energy storage performance were investigated. The results indicate that appropriate Bi(Mg 0.5 Zr 0.5 )O 3 content can effectively enhance the relaxor ferroelectric characteristics and improve the dielectric breakdown strength by forming fine grain sizes and diminishing oxygen vacancy concentrations. Therefore, the optimal W rec of 6.75 J/cm 3 and a η of 79.44% were simultaneously obtained in NBT-SBT-0.15BMZ at 20 °C and 385 kV/cm. Meanwhile, thermal stability (20-180 °C) and frequency stability (1-200 Hz) associated with the ultrafast discharge time of ~49.1 ns were also procured in the same composition, providing a promising material system for applications in power pulse devices.