Simultaneous Enhancement of Energy Storage and Hardness Performances in (Na 0.5 Bi 0.5 ) 0.7 Sr 0.3 TiO 3 -Based Relaxor Ferroelectrics Via Multiscale Regulation.

For (Na 0.5 Bi 0.5 ) 0.7 Sr 0.3 TiO 3 -based (BNST) energy storage materials, a critical bottleneck is the early polarization saturation and low breakdown electric field ( E b ), which severely limits further development in the field of advancing pulsed power capacitors. Herein, a strategy, via multiscale regulation, including synergistically manipulation of the domain configuration and microstructure evolution in BNST-based ceramics, is propounded through introducing LiTaO 3 (LT). The composition-driven fine domain size, as demonstrated by macroscale (size effect and dielectric response) and mesoscale (domains relaxor behavior) analysis, provides robust evidence of delayed polarization saturation and large polarization difference. Theoretical simulations and experimental results confirm that the fine grain size, uniform grain size distribution, and insignificant secondary phase contribute to the enhancements of E b . Further analyses of the intrinsic electronic structure reveal the intrinsic mechanism for enhancing E b via first-principles calculations on the basis of density functional theory. Consequently, owing to improved E b , delayed polarization saturation, and refined grain size, excellent comprehensive performances [high W rec of 5.52 J/cm 3 , large η of 85.68%, high hardness H of 7.06 GPa, and broad operating temperature range (20-140 °C)] are realized. We believe that these findings can provide a thorough understanding of the origins of excellent comprehensive performances in BNST-based ceramics as well as some guidance in the exploration of materials with high-performance lead-free capacitors for application in future pulsed power systems.