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

Abstract Developing dielectric ceramics with high energy storage performance (ESP) is essential for miniaturizing and integrating high‐power pulse capacitors. Sr 2 NaNb 5 O 15 ‐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, Bi 3+ and Ti 4+ ions were introduced into the Sr 2 NaNb 5 O 15 ceramic, aiming to modulate the ferroelectric polarization and relaxor behavior synergistically. An excellent recoverable energy density ( W rec ∼ 4.08 J/cm 3 ) and a high efficiency ( η ∼ 84.59%) were concurrently attained in the Sr 1.85 Bi 0.15 NaNb 4.85 Ti 0.15 O 15 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 Bi 3+ and Ti 4+ ions co‐doped Sr 2 NaNb 5 O 15 ceramics possess great potential for dielectric capacitor applications.