Phase engineering in NaNbO₃ antiferroelectrics for high energy storage density

The NaNbO₃ antiferroelectrics have been considered as a potential candidate for dielectric capacitors applications. However, the high-electric-field-unstable antiferroelectric phase resulted in low energy storage density and efficiency. Herein, good energy storage properties were realized in (1-x)NaNbO₃-xNaTaO₃ ceramics, by building a new phase boundary. As a result, a high recoverable energy density (W_rec) of 2.2 J/cm³ and efficiency (η) of 80.1% were achieved in 0.50NaNbO₃-0.50NaTaO₃ ceramic at 300 kV/cm. The excellent energy storage performance originates from an antiferroelectric-paraelectric phase boundary with simultaneously high polarization and low hysteresis, by tailoring the ratio of antiferroelectric and paraelectric phases. Moreover, the 0.50NaNbO₃-0.50NaTaO₃ ceramic also exhibited good temperature and frequency stability, together with excellent charge-discharge performance. The results pave a good way of designing new NaNbO₃-based antiferroelectrics with good energy storage performance.