Excellent comprehensive energy storage properties of novel lead-free NaNbO 3 -based ceramics for dielectric capacitor applications

NaNbO 3 (NN) is generally considered as one of the most promising lead-free antiferroelectric (AFE) perovskite materials with the advantages of low cost, low density and nontoxicity. However, the metastable ferroelectric phase causes a large remanent polarization ( P r ) at room temperature, seriously hindering the achievement of excellent energy storage properties. Although via the strategy of lowering the radius of B-site ions and polarizability, a number of AFE NaNbO 3 -based solid solutions with double polarization–electric field loops are successfully constructed, the hysteresis losses are still too large and the P r value cannot be reduced to near zero. In this study, Bi(Mg 2/3 Nb 1/3 )NbO 3 (BMN) was chosen to partially substitute the pure NaNbO 3 with the intention of enhancing antiferroelectricity and constructing a local random field simultaneously. These short-range interactions effectively suppress the hysteresis loss and P r , and slim hysteresis loops were observed in the NN–BMN ceramics. A high charged energy density (3.4 J cm −3 ) and recoverable energy storage density (2.8 J cm −3 ) with high efficiency (82%) were achieved under 300 kV cm −1 for NN–0.10BMN. Superior stabilities and underdamped discharge abilities were also achieved for NN–0.15BMN with a slightly smaller recoverable energy storage density (2.4 J cm −3 ) but even higher efficiency (90%). The results reported here demonstrate great potential of the designed NN–BMN ceramics for high-temperature capacitors.