Phase evolution, dielectric thermal stability, and energy storage performance of NBT-based ceramics via viscous polymer process

https://doi.org/10.1016/j.jallcom.2024.176577

There is an urgent need to develop stable and high-energy storage dielectric ceramics; therefore, in this study, the energy storage performance of Na_0.5-xBi_0.46-xSr_2xLa_0.04(Ti_0.96Nb_0.04)O_3.02 (x = 0.025–0.150) ceramics prepared via the viscous polymer process was investigated for energy storage. It was found that with increasing Sr²⁺ content, the material transforms from a mixture of rhombohedral and tetragonal phases (x = 0.025) to a mixture of orthorhombic and pseudo-cubic phases (x = 0.15). The emergence of a dielectric plateau for the sample with x = 0.15 widens the applicability of the host compound. Finite element simulations show that a smaller grain size has a beneficial effect on the critical breakdown electric field and that the relaxor transformation benefits from the reduction of residual polarization (P_r). The obtained ceramics achieve a value of 6.69 J/cm³ for the energy storage density (W_rec) and 89.48 % for the energy storage efficiency (η) under an applied electric field of 400 kV/cm, with a discharge time (t_0.9) of 0.168 μs at 90 % of the energy under an electric field of 280 kV/cm, and a power density (P_d) of 148 MW/cm³. This study shows a novel strategy for the modification of the dielectric and ferroelectric properties of NBT-based ceramics, providing an effective way to expand the operational temperature range and improve energy storage performance.