Improvement of energy storage properties of BNT-based ceramics via compositional modification

Lead-free ceramic capacitors are extensively utilized in pulsed power systems for their environmentally friendly characteristics, high power density, and fast charging/discharging rate. However, it remains highly challenging to achieve concurrent improvements in both recoverable energy storage density (W_rec) and efficiency (η). In this study, Ta₂O₅ with a wide bandgap (∼4 eV) was chosen in complex with Mg²⁺ ions to form Ba(Mg_1/3Ta_2/3)O₃ as the second phase of a BNT-based solid solution. Combined with phase modulation, a compositional disorder of equipotential sites is formed in chalcogenide crystals, which in turn induces charge disorder generating localized random fields. We have designed and prepared a set of binary (1-x)Bi_0.5Na_0.5TiO₃-xBa(Mg_1/3Ta_2/3)O₃ (BNT-xBMT) ceramics using a conventional solid-phase method. An ultra-high breakdown field strength (E_b) value (245 kV/cm) was attained in 0.80BNT-0.20BMT ceramic, resulting in desirable values of W_rec (3.99 J/cm³) and η (92.0 %). These results offer a new strategy for designing high entropy ceramic materials of high performance in the future.