Superior Energy-Storage Properties in BiNaTiO-Based Lead-Free Ceramics via Simultaneously Manipulating Multiscale Structure and Field-Induced Structure Transition.

Pratical applications have put forward great challenges to the comprehensive energy-storage performance of ceramic material. Here, a novel route of simultaneously manipulating multiscale structure and the field-induced structural transformation in (BiNa)TiO-based ceramics is proposed to address the above concern. The multiscale structure of 0.88(BiNa)TiO-0.12BaTiO solid solutions such as grain and domain size, band gap, and phase structure can be adjusted by adding antiferroelectric NaNbO. Simultaneously, a field-induced 4 relaxor antiferroelectric to 4 ferroelectric phase transformation can be obtained by constructing a 4-4 phase boundary, which is expected to require a lower energy barrier compared with the field-induced 4 relaxor antiferroelectric to 3 ferroelectric transformation in other (BiNa)TiO-based ceramics. The optimized field-induced structural transformation behavior and the formation of nanodomains enables a minimized polarization hysteresis but an enhanced maximum polarization. Moreover, the decreased grain size together with increased band gap leads to a significantly improved breakdown strength. Accordingly, a giant energy density ∼ 8.0 J/cm, a high efficiency η ∼ 86%, a short discharging time ∼ 41 ns, and a good temperature stability ( = 1.32 ± 0.12 J/cm, η = 88.5% ± 2.5% @ 25-200 °C) are simultaneously obtained in 0.63(BiNa)TiO-0.12BaTiO-0.25NaNbO relaxor antiferroelectric ceramics, demonstrating large potentials for the ceramic capacitor applications.