Enhanced relaxation behavior and energy storage properties in (Al0.5Nb0.5)4+ complex ions modified Na0.5Bi0.5TiO3-based ceramics under low electric field

In recent decades, high polarization and low residual polarization lead-free relaxor ferroelectric ceramics have attracted lots of focus due to their great potential in dielectric capacitors for energy storage. In this work, Na0.35Bi0.35Sr0.3Ti(1-x)(Al0.5Nb0.5)xO3 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05) lead-free ceramics have been fabricated by the traditional solid-stated reaction method. By doping (Al0.5Nb0.5)4+ complex ions into 0.7Na0.5Bi0.5TiO3-0.3SrTiO3, pure perovskite phases and reduced grain sizes are obtained. Increasing the AN concentration not only moves the Ts toward the lower temperature, but also keeps the permittivity at a high average value, which shows a good thermal stability of the dielectric properties (εr150°C ∼ 3903 ± 15% in the range of 42–232 °C). Furthermore, Na0.35Bi0.35Sr0.3Ti(1-x)(Al0.5Nb0.5)xO3 presents a reduced residual polarization due to the improved relaxor behavior, and achieves a moderate energy storage property at low electric field of 155 kV/cm (when x = 0.04 Wrec is 1.85 J/cm3, and η is 89.0%). More importantly, the ceramic also possesses great frequency, temperature and cycle stability. Hence, the (Al0.5Nb0.5)4+ modified 0.7Na0.5Bi0.5TiO3-0.3SrTiO3 ceramics have exhibited a potential application in dielectric capacitors for energy storage.