Synergistic optimization strategy enhanced the energy storage performance of NaNbO3-based relaxation antiferroelectric ceramics

Abstract

Due to the continuous popularization of electronic facilities and the increasing requirements for the green environment, the development of lead-free ceramics is more in line with policy orientation and market demand. Among the lead-free dielectric materials, antiferroelectric sodium niobate attracts much attention because of its low price of raw materials and high breakdown field strength (E_b). However, its relatively high remanent polarization results in extremely significant energy loss. This drawback largely limits its effective application in practical application scenarios. In this study, La³⁺ and Bi³⁺ were used to substitute for the A-site, and Mg²⁺ and Ta⁵⁺ were used to substitute for the B-site to enhance the relaxation behavior. On this basis, the linear dielectric CaTiO₃ was added to improve the insulation of the ceramics. By inducing polar nanoregions (PNRs) to reduce the remanent polarization strength of the ceramics, (1-x)[0.9NaNbO₃-0.1(La_0.3Bi_0.7Mg_2/3Ta_1/3)O₃]-xCaTiO₃ (x = 0.05、0.10、0.15、0.20) ceramics were successfully prepared. The results showed that with the increase of CaTiO₃ content, the overall trend of the activation energy of the ceramics increased, and the difficulty of carrier migration increased. As a result, the breakdown field strength was significantly improved, rising from the original 350 kV/cm to 470 kV/cm. When x = 0.15, the 0.15CT ceramic achieved a high effective energy storage W_rec = 4.02 J/cm³ and energy storage efficiency ƞ = 87% under 470 kV/cm. Furthermore, this work exhibited outstanding temperature stability and an ultrafast charge–discharge rate (t_0.9) of 21 ns. This research provides a new idea for the development of future high-performance capacitors.