Improved energy storage properties of Bi(Mg_2/3Nb_1/3)O₃-modified 0.8Bi_0.5Na_0.5TiO₃–0.2SrTiO₃ ceramics

The pursuit of lead-free ceramic capacitors with superior energy storage properties has garnered increasing attention. The energy storage properties of Bi_0.5Na_0.5TiO₃ (BNT) can be feasibly adjusted by forming solid solutions with other components. Herein, 0.8Bi_0.5Na_0.5TiO₃–0.2SrTiO₃–xBi(Mg_2/3Nb_1/3)O₃ (BNT–ST–xBMN) ceramics were synthesized via citrate combustion technology. The results show that BMN-doped BNT–ST ceramics induce dielectric relaxation behavior and slim hysteresis loops are realized. An optimized recoverable energy storage density (W_re of 2.85 J/cm³) and efficiency (η of 83%) are obtained in 1.5 mol% BMN-doped BNT–ST ceramic under relatively low electric field of 200 kV/cm. The ceramics show excellent frequency stability (W_re varies < 1.4% and η varies < 1% at 10 to 100 Hz). Moreover, both W_re and η maintain an increasing trend with increasing temperature.