Excellent comprehensive energy storage properties of novel lead-free NaNbO3-based ceramics for dielectric capacitor applications

Abstract

NaNbO₃ (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 NaNbO₃-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_2/3Nb_1/3)NbO₃ (BMN) was chosen to partially substitute the pure NaNbO₃ 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.