High energy-storage performance in multiple roles modified NaNbO3-Ba(Fe0.5Nb0.5)O3 lead-free relaxors

NaNbO3-based lead-free energy-storage ceramics have been extensively investigated owing to their large bandgap and antiferroelectric characteristics, which are important candidates for next-generation pulse power capacitors. However, the low energy-storage efficiency caused by antiferroelectric-ferroelectric phase transition strongly restricts their development. To overcome this phase transition characteristic, here, Ba(Fe0.5Nb0.5)O3 is considered to be introduced into NaNbO3 ceramic as a ferroelectric stabilizer, relaxation agent, and sintering aid with multiple roles, leading to the synergistic effect of substantially weakened antiferroelectricity, established ergodic relaxor, destroyed long-range ordered polarization, decreased grain size and delayed polarization saturation. As a result, a high Wrec of ∼3.55 J/cm3 and a large η of ∼84.1% accompanied by an ultrafast discharge rate of ∼30 ns are simultaneously realized in 0.82NaNbO3-0.18Ba(Fe0.5Nb0.5)O3 relaxor ferroelectric ceramic. This work demonstrates that multi-role regulation is an effective strategy for designing new lead-free dielectric ceramics with excellent energy-storage performance.