Improvement of Energy Storage Properties of NaNbO3-Based Ceramics through a Relaxation Strategy


 NaNbO3 (NN) is a widely studied antiferroelectric ceramics. However, NN ceramics always exhibit a square P-E loop with larger Pr, originating form an irreversible antiferroelectric-ferroelectric (AFE-FE) phase transition under an applied electric field, which limits further development. Here, a novel lead-free relaxor ferroelectric ceramic, (1-x)NaNbO3-x(0.5Bi0.5Na0.5TiO3-0.5Ba0.3Sr0.7TiO3) [(1-x)NN-xBNBST, 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 shows that the addition of BNBST significantly improved the relaxor behavior of the NN, which is effective for enhancing the Wrec and ƞ of NN-based ceramics. When x = 0.2, the ceramic obtains a high recoverable energy storage density (Wrec = 2.024 J/cm3) and energy storage efficiency (ƞ = 63 %) at a low electric field of 130 kV/cm. Meanwhile, the polarization-electric field 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.