Superior Energy-Storage Properties in Bi 0.5 Na 0.5 TiO 3 -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 (Bi 0.5 Na 0.5 )TiO 3 -based ceramics is proposed to address the above concern. The multiscale structure of 0.88(Bi 0.5 Na 0.5 )TiO 3 -0.12BaTiO 3 solid solutions such as grain and domain size, band gap, and phase structure can be adjusted by adding antiferroelectric NaNbO 3 . Simultaneously, a field-induced P 4 bm relaxor antiferroelectric to P 4 mm ferroelectric phase transformation can be obtained by constructing a P 4 mm - P 4 bm phase boundary, which is expected to require a lower energy barrier compared with the field-induced P 4 bm relaxor antiferroelectric to R 3 c ferroelectric transformation in other (Bi 0.5 Na 0.5 )TiO 3 -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 W rec ∼ 8.0 J/cm 3 , a high efficiency η ∼ 86%, a short discharging time t 0.9 ∼ 41 ns, and a good temperature stability ( W rec = 1.32 ± 0.12 J/cm 3 , η = 88.5% ± 2.5% @ 25-200 °C) are simultaneously obtained in 0.63(Bi 0.5 Na 0.5 )TiO 3 -0.12BaTiO 3 -0.25NaNbO 3 relaxor antiferroelectric ceramics, demonstrating large potentials for the ceramic capacitor applications.