Improved energy storage properties in NaNbO3 modified 0.7Bi0.5Na0.5TiO3-0.3SrTiO3 ceramics under low electric field

Lead-free relaxation ferroelectrics have attracted additionally attention due to their high energy storage density (Wrec), excellent stability and environmental friendly characteristics. Here, a novel type lead-free relaxation ferroelectrics 0.7Bi0.5Na0.5TiO3-(0.3-x)SrTiO3-xNaNbO3 (abbreviated as 0.7BNT-(0.3-x) ST-xNN), x = 0–0.1) were designed and synthesized using solid state reaction method. After introducing the antiferroelectric material NN into BNT-ST system, obvious structural distortion, reduced average grain size and enhanced breakdown electric field (Eb) were observed, which contributes to the improved Wrec. The optimized energy storage characteristics was obtained in the 0.7BNT-0.24ST-0.06NN ceramics, demonstrating the recoverable energy storage density of 1.46J/cm3 with the energy storage efficiency of 79.58% under low electric field of 108 kV/cm, exhibiting 1.34 and 1.1 times enhancement compared to the 0.7BNT-0.3ST ceramic. Meanwhile, the energy storage property of 0.7BNT-0.24ST-0.06NN ceramic also exhibited considerable frequency (10Hz–150Hz) and temperature (20°C–120 °C) stability. This work indicates that the addition of antiferroelectric NN into relaxation ferroelectric material is an effective strategy to design high-performance BNT-based ceramic capacitors for energy storage applications. •Two obvious dielectric peaks (Ts and Tm) for all samples can be observed near 100 °C and 250 °C in Ɛr -T curve. Both Ts and Tm shift to lower temperatures with increasing of x.•Wrec of 1.46 J/cm3 and η of 79.58% are obtained at 108 kV/cm for the 0.7BNT-0.24ST- 0.06NN ceramic.•Both Wrec and η of 0.7BNT-0.24ST-0.06NN ceramic also have better frequency (10Hz–150Hz) and temperature (20°C–120 °C) stability.