Enhancing the dielectric and energy storage properties of lead-free Na0.5Bi0.5TiO3–BaTiO3 ceramics by adding K0.5Na0.5NbO3 ferroelectric

A novel strategy of enhancing the dielectric and energy storage properties of Na_0.5Bi_0.5TiO₃–BaTiO₃ (NBT–BT) ceramics by introducing a K_0.5Na_0.5NbO₃ (KNN) ferroelectric phase is proposed herein, and its underlying mechanism is elucidated. The lead-free KNN ceramic decreases the residual polarisation and increases the electric breakdown strength of the NBT–BT matrix through the simultaneous modification of its A-sites and B-sites. The obtained NBT?BT?x?KNN ceramics have a perovskite structure with unifying grains. A bulk 0.9NBT–BT–0.1KNN ceramic sample with a thickness of 0.2 mm possesses a high energy storage density of 2.81 J/cm³ at an applied electric field of 180 kV/cm. Moreover, it exhibits good insulation properties and undergoes rapid charge and discharge processes. Therefore, the obtained 0.9NBT–BT–0.1KNN ceramic can be potentially used in high-power applications because of its high energy density, good insulation properties, and large discharge rate.