Superb Energy Storage Capability for NaNbO₃ -Based Ceramics Featuring Labyrinthine Submicro-Domains with Clustered...

Designing superb dielectric capacitors is valuable but challenging since achieving simultaneously large energy-storage (ES) density and high efficiency is difficult. Herein, the synergistic effect of grain refining, bandgap widening, and domain engineering is proposed to boost comprehensive ES properties by incorporating CaTiO₃ into 0.92NaNbO₃ -0.08BiNi_0.67 Ta_0.33 O₃ matrix (as abbreviated NN-BNT-xCT). Apart from grain refining and bandgap widening, multiple local distortions embedded in labyrinthine submicro-domains, as indicated by diffraction-freckle splitting and ½-type superlattices, produce slush-like polar clusters for the NN-BNT-0.2CT ceramic, which should be ascribed to the coexisting P4bm, P2₁ ma, and Pnma₂ phases. Consequently, a high recoverable ES density W_rec of ≈ 7.1 J cm^-3 and a high efficiency η of ≈ 90% at 646 kV cm^-1 is achieved for the NN-BNT-0.2CT ceramic. Such hierarchically polar structure is favorable to superb comprehensive ES properties, which provide a strategy for developing high-performance dielectric capacitors.