Superior energy storage properties in lead-free NaNbO₃-based relaxor antiferroelectric ceramics via a combined optimization strategy

NaNbO3 (NN)-based lead-free antiferroelectric (AFE) ceramics have promising characteristics for utilization in high power electronic devices. In this work, relaxor AFE orthorhombic R-phase ceramics (1 - x)NaNbO3-x(0.58(Bi0.5Na0.5)TiO3-0.06BaTiO(3)-0.2SrTiO(3)-0.16Bi(Mg0.5Zr0.5)O-3) (NN-x) with outstanding comprehensive energy storage properties (ESPs) were successfully prepared using a traditional solid-state method and a tape-casting method via a combined optimization strategy. Through this strategy, a recoverable energy density (W-rec) of 6.48 J cm(-3) and an energy storage efficiency (eta) of 77.2% were obtained for x = 0.30 bulk ceramic. The XRD patterns, Raman spectra and TEM analyses verified the AFE R phase at room temperature for all specimens. Interestingly, a stable R phase was obtained by introducing a solid solution with a high tolerance factor, instead of a low tolerance factor. Then, the thickness of the optimal specimen, i.e., x = 0.30 sample, was reduced to similar to 11 mu m using the tape-casting process to further improve the ESPs. The increased compactness and reduced thickness significantly augment the maximal breakdown electric field. Therefore, an exceptional W-rec = 11.09 J cm(-3) and an eta = 85.7% were achieved at a high breakdown electric field E-b = 1200 kV cm(-1). Meanwhile, excellent temperature stability (20-150 degrees C) and frequency stability (1-500 Hz) were also observed in the specimen. This work provides a novel strategy to stabilize the AFE R phase and enhance the ESPs of dielectric materials.