High energy storage density and ultrafast discharging realized in three-layer Aurivillius ferroelectric ceramics through pyrochlore phase regulation

The development of Aurivillius-phase ceramics with excellent energy storage performance is crucial for applications in pulsed power systems and high-temperature capacitors. In this study, Bi 3.25 La 0.75 Ti 3-x Sn x O 12 (x = 0.0, 0.03, 0.06, 0.12, 0.20) ceramics were prepared using the solid-state reaction method. The effects of Sn 4+ doping and two-step sintering on their microstructure and energy storage properties were systematically investigated. The results indicate that Sn 4+ doping induces the formation of a pyrochlore phase, which plays a dual role in the energy storage process. However, an excessive amount of this phase reduces the material's polarization ability, thereby compromising its energy storage performance. Two-step sintering promoted grain recrystallization and growth, reduced the proportion of the pyrochlore phase, and optimized the ceramic microstructure. As a result, BLTS (x = 0.12) achieved an energy storage density of 1.6 J/cm 3 under an applied electric field of 517 kV/cm. Moreover, all samples exhibited ultrafast discharge characteristics, with τ 0.9 as short as 16 ns. This study provides an initial contribution to the exploration of Aurivillius-phase ceramics as electrostatic energy storage media. It is our expectation that this work will encourage greater focus on this material system, ultimately enabling its advancement to a level of performance comparable to that of perovskite and tungsten bronze dielectrics. • A quasi-linear pyrochlore phase was successfully introduced into the AP phase with a controllable proportion. • The grain microstructure of Aurivillius layer-structured compounds and the ratio a pyrochlore was controlled by annealing process. • An energy storage density of 1.6 J cm -3 and an ultrafast discharge τ 0.9 of 16 ns represents the current state-of-the-art.