Synergistic modulation of ferroelectric polarization and relaxor behavior of Sr₂NaNb₅O₁₅-based tungsten bronze ceramic

Developing dielectric ceramics with high energy storage performance (ESP) is essential for miniaturizing and integrating high-power pulse capacitors. Sr2NaNb5O15-based tungsten bronze ferroelectric ceramics have been highly investigated for dielectric energy storage applications recently. However, the difficulty in concurrently obtaining large polarization and strong relaxor characteristics greatly hinders the ESP improvement. In this work, Bi3+ and Ti4+ ions were introduced into the Sr2NaNb5O15 ceramic, aiming to modulate the ferroelectric polarization and relaxor behavior synergistically. An excellent recoverable energy density (W-rec similar to 4.08 J/cm(3)) and a high efficiency (eta similar to 84.59%) were concurrently attained in the Sr1.85Bi0.15NaNb4.85Ti0.15O15 composition due to the boosted polarization and enhanced relaxor nature. Moreover, this ceramic also exhibited a high current density (863.06 A/cm(2)) and a large power density (94.94 MW/cm(3)). All these characteristics demonstrate that the Bi3+ and Ti4+ ions co-doped Sr2NaNb5O15 ceramics possess great potential for dielectric capacitor applications.