Improvement of Energy Storage Properties of NaNbO 3 -Based Ceramics through a Relaxation Strategy

NaNbO3 (NN) is a widely studied antiferroelectric ceramics in recent years. However, NN ceramics always exhibit a square P - E loop with larger P r , originating form an irreversible antiferroelectric-ferroelectric (AFE-FE) phase transition under an applied electric field and limit the further development. In this paper, a novel lead-free relaxor ferroelectric ceramic, (1− x )NaNbO 3 - x (0.5Bi 0.5 Na 0.5 TiO 3 −0.5Ba 0.3 Sr 0.7 TiO 3 ) [(1− x )NN- x BNBST, x = 0, 0.10, 0.15, 0.20, 0.25, 0.30], was designed and prepared via a local random field relaxation strategy. Dielectric testing show that the addition of BNBST significantly improved the relaxor behavior of the NN, which is effective for enhancing the W rec and η of NN-based ceramics. When x = 0.2, the ceramic obtains a high recoverable energy storage density ( W rec = 2.024 J cm −3 ) and energy storage efficiency ( η = 63%) at a low electric field of 130 kV cm −1 . Meanwhile, the polarization-electric field ( P-E ) hysteresis loops and charge-discharge results of the sample with x = 0.2 at different temperatures and frequencies show that it is a prospective material for pulsed energy storage capacitors.