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

Abstract

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(Bi_0.5Na_0.5)TiO₃–0.06BaTiO₃–0.2SrTiO₃–0.16Bi(Mg_0.5Zr_0.5)O₃) (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 (η) 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 ∼11 μm 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 η = 85.7% were achieved at a high breakdown electric field E_b = 1200 kV cm⁻¹. Meanwhile, excellent temperature stability (20–150 °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.