High Energy Storage Density and Excellent High-Temperature Stability under Low Electric Field in (Ba_0.12Sr_0.28K_0.3–xBi_0.3Na_x)TiO₃ High-Entropy Ceramics

With the continuous advancement of the application of ceramic capacitors, excellent energy storage performance under low electric fields is extremely important for ceramic capacitors and the demand for high-temperature stable ceramic capacitors is also urgent. In this work, a perovskite oxide, (Ba 0.12 Sr 0.28 K 0.3– x Bi 0.3 Na x )TiO 3 (where x = 0.125, 0.15, 0.175, 0.2), is designed and prepared using a high-entropy strategy. This approach addresses the poor energy storage and high-temperature stability of dielectric ceramics by increasing the configurational entropy (Δ S config ). The x = 0.15 sample has the highest Δ S config and gains outstanding energy storage density ( W rec ) of 2.07 J/cm 3 and energy storage efficiency (η) of 84.5% at the low electric field of 210 kV/cm. The variation of W rec and η at 40–140 °C is less than 4.9% and 2.0%, respectively. Furthermore, these high-entropy ceramics also demonstrate excellent dielectric temperature stability (Δε r /ε 150 °C ≤ ±15%, 42–317 °C). The results show that the high-entropy strategy is an effective way to achieve the excellent properties of dielectric ceramics.