Excellent low-field energy storage properties and high density achieved in Bi0.48Na0.48Ba0.04TiO3-based oxide ceramics via interposing (Na0.97Bi0.01)+/Ta5+ at A/B sites

Lead-free dielectric ceramics are one of the most essential candidates for reforming pulsed power capacitors; nevertheless, formidable hurdles are posed by their high hysteresis and low energy storage properties. Dielectric ceramic capacitors with ultra-high energy storage performance usually need to be realized under the conditions of high electric field. Its application in miniaturized integrated electronic devices is severely limited. In this work, A-site deficiency was designed in Na_0.97Bi_0.01TaO₃-modified Bi_0.48Na_0.48Ba_0.04TiO₃ lead-free relaxor ferroelectric ceramics to increase oxygen vacancy content, achieve local disorder and construct local multi-phase coexistence, which causes low hysteresis with excellent high energy density at low electric fields (LEFs). Results indicated that the introduction of A-site deficiency improved the concentration of oxygen vacancies while reconstructing the local structure disorder. Benefiting from the synergistic effect of both, a high energy recoverable density of ∼7.98 J cm⁻³ and efficiency η of ∼83.7% was determined in 0.84Bi_0.48Na_0.48Ba_0.04TiO₃-0.16Na_0.97Bi_0.01TaO₃-modified ceramics under 330 kV cm⁻¹. Furthermore, the modified ceramics had an acceptable frequency stability (0.5–130 Hz) and temperature stability (RT – 180 °C) with exact discharge density. These findings can lead to the development of an innovative strategy for fabricating energy-storage ceramics under low electric field conditions.