High energy storage and thermal stability under low electric field in Bi0.5Na0.5TiO3-modified BaTiO3-Bi(Zn0.25Ta0.5)O3 ceramics

Abstract

Dielectric energy storage capacitors have been comprehensively investigated for application in advanced electronic systems. Compared to other types of ceramic capacitors, BaTiO3-BiMeO3 lead-free composite relaxor ferroelectric ceramics (where Me represents trivalent or trivalent composite ion) are excellent dielectric energy storage candidates in pulsed power fields. However, the properties of most existing BT-based energy storage ceramics are not satisfactory in some practical aspects, and feasible guidance on efficient composting material systems with large recoverable energy storage density (Wrec) for ultralow electric fields is lacking. Herein, for the first time, lead-free relaxor ferroelectric (1-x)[0.9BaTiO3-0.1Bi(Zn0.25Ta0.5)O3]-xBi0.5Na0.5TiO3 ceramics with x = 0, 0.1, 0.2, 0.3, and 0.4 were synthesized via composite strategy using the traditional solid-state process. The used strategy combined the complementary advantages of both BT-BZT and BNT to greatly increase the saturation polarization (Ps) and shift the stable temperature range of permittivity to high-temperature region, achieving higher energy storage density and improved temperature stability. Optimum energy storage performances with a high Wrec of 4.18 J/cm3 and comparatively high η of 84.01% were simultaneously achieved in the relatively low electric field of 230 kV/cm. Moreover, the ceramic obtained at x = 0.3 showed excellent temperature stability with the change rate of Wrec < 5% and η < 6% throughout a broad temperature range (20 °C ∼ 170 °C). This ceramic (x = 0.3) simultaneously possesses superior pulse performance, exhibiting the t0.9 of 232 ns and Wdis of 2.51 J/cm3. Overall, the employed composite strategy design is effective for obtaining energy storage capacitors with excellent performance for future advanced pulsed power devices.