Superior energy storage properties in NaNbO3-based ceramics via synergistically optimizing domain and band structures

Abstract

Environment-friendly ceramic capacitors with outstanding energy storage properties (ESPs) are greatly desired for advanced pulsed power systems. However, it is still a great challenge to develop lead-free dielectric materials with simultaneous excellent recoverable energy storage density (W_rec) and energy storage efficiency (η). In the present work, a synergistic optimization strategy with regard to ferroelectric domain and band structures is applied to NaNbO₃ (NN)-based ceramics, where the introduction of Bi³⁺ induces elongated ferroelectric P–E loops due to nanodomain formation, and the further modification of the Ta doping content remarkably reduces the grain size and widens the band gap (E_g), leading to a high breakdown strength. As a result, the involved Na_0.7Bi_0.1Nb_0.9Ta_0.1O₃ ceramics exhibit excellent comprehensive ESP (W_rec = 7.33 J cm⁻³, η = 83.68%, E_b = 530 kV cm⁻¹) and good stability. Moreover, an ultrafast discharge time of 60 ns and high power density of 320.21 MW cm⁻³ are also achieved. Na_0.7Bi_0.1Nb_0.9Ta_0.1O₃ ceramics with an uncomplicated chemical composition and prominent properties demonstrate promising applications in pulsed power systems and the synergistic optimization strategy in this study offers an important reference for future lead-free ceramic capacitors.