Furthermore, the ceramic also exhibited a large current density ( C D) of 1268.4 A/cm 2 and power density ( P D) of 177.6 MW/cm 3 at 28 kV/mm, offering prospective applications in high-power capacitors. Finally, the sample with x = 0.12 showed an ultrahigh W rec value of 16.2 J/cm 3 and satisfactory η of 82.3% at 97 kV/mm, outperforming most state-of-the-art counterparts. Specifically, the E b was significantly improved because of the reduced grain size, small sample thickness, exceptionally low dielectric loss, and a moderate dielectric constant. Consequently, novel relaxor antiferroelectric ceramics were successfully obtained, which simultaneously revealed the features of relaxor and antiferroelectricity. In addition, the relaxor characteristic was demonstrated by the diffuse dielectric peaks, slim P–E curves, flattened Raman peaks, and I–E curves. With the help of composition regulation, the ceramics not only exhibited a stable antiferroelectric phase but also underwent a structural transformation from an antiferroelectric P ( Pbma) phase to R ( Pnma) phase, as confirmed by the temperature-dependent dielectric constants, Raman spectra, X-ray diffraction (XRD) refinement, pinched polarization-electric field ( P–E) curves, and four-peak current-electric field ( I–E) curves. In this study, the relaxor antiferroelectric (1– x)NaNbO 3– x(0.55BiFeO 3-0.45SrTiO 3) ceramics were elaborately designed and systematically explored. However, their relatively low recoverable energy storage density ( W rec < 10 J/cm 3), limited by the electric breakdown strength ( E b < 60 kV/mm), and low efficiency (η < 80%), generated by large hysteresis during the antiferroelectric–ferroelectric phase transition, have seriously restricted their application in portable and compact electronic devices. Lead-free antiferroelectric ceramics have drawn widespread interest recently on account of their environmentally friendly components and potential applications in high-power systems.
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