High energy storage density under low electric fields in BiFeO3-based ceramics with max configurational entropy

Dielectric capacitors play an increasingly important role in power systems because of their fast charging and discharging speed. Applications are usually limited due to the low W rec . We design materials with high values of Δ P ( P max - P r ) and recoverable energy storage density( W rec ) from the high entropy perspective. Two single phases with a large Curie temperature T c difference have been selected, which leads to the enlarged entropy. The ceramics (Bi 0.85 Nd 0.1 Sm 0.05 ) 1- x Ba x )(Fe 1- x Ti x )O 3 (BNSBFT x ) are prepared by the solid-state reaction. As x increases, the corresponding configuration entropy( S config ) goes from 1.4 R to 1.52 R. The increased entropy destroys the long-range order, accompanied by the reduced remanent polarization( P r ) and the improved W rec . The W rec of BNSBFT 0.5 ceramics reaches 4.9 J/cm 3 at a low field of 250 kV/cm. Both temperature change(∼ 0.5% from 30 °C to 140 °C) and frequency variation(∼ 4.8% from 1 Hz∼50 Hz) in W rec show excellent stability.