Significantly enhanced energy-storage properties in NaNbO3-based relaxor ferroelectric ceramics via introducing a wide band-gap linear dielectric

The achievement of simultaneous high energy-storage density and efficiency is a long-standing challenge for dielectric ceramics. Herein, a wide band-gap lead-free ceramic of NaNbO3–BaZrO3 featuring polar nanoregions with a rhombohedral local symmetry, as evidenced by piezoresponse force microscopy and transmission electron microscopy, were reported to exhibit a giant energy-storage density of ∼5.0 J/cm3 and a high efficiency of ∼85 % as well as excellent charge-discharge properties simultaneously. Enhanced breakdown strength from a synergistic effect of wider band gap and decreased grain size provides a prerequisite for improving energy-storage performance. Meanwhile, the substitution of linear dielectric BaZrO3 can not only adjust the low-temperature ferroelectric rhombohedral phase of NaNbO3 into near room temperature, but also significantly reduce the FE domain size owing to the increased local random fields. Therefore, suppressed polarization hysteresis and delayed polarization saturation can be observed with increasing BaZrO3 content, leading to the significantly enhanced overall energy-storage properties.