Phase Evolution, Dielectric Thermal Stability, and Energy Storage Performance of NBT-Based Ceramics via Viscous Polymer Process

Abstract

There is an urgent need to develop stable and high-energy storage dielectric ceramics; therefore, in this study, the energy storage performance of Na0.5-xBi0.46-xSr2xLa0.04(Ti0.96Nb0.04)O3.02 (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 (Pr). The obtained ceramics achieve a value of 6.69J/cm3 for the energy storage density (Wrec) and 89.48% for the energy storage efficiency (η) under an applied electric field of 400kV/cm, with a discharge time (t0.9) of 0.168 μs at 90% of the energy under an electric field of 280kV/cm, and a power density (Pd) of 148MW/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.