Excellent energy storage properties in (Bi0.4Na0.2K0.2Ba0.2)(Ti0.95Zr0.05)O3-based high-entropy ceramics by introduction of Sr(Mg1/3Nb1/3Ta1/3)O3 medium-entropy endmember

In this study, a series of high-entropy lead-free relaxor ferroelectrics (1-x)(Bi0.4Na0.2K0.2Ba0.2)(Ti0.95Zr0.05)O3–xSr(Mg1/3Nb1/3Ta1/3)O3 are designed and synthesized. As x increases, the corresponding configurational entropy (∆Sconfig) varies from 1.53 R to 2.10 R. The long-range ordered structure of the ferroelectric domains is disrupted, accompanied by the reduced remanent polarization (Pr) and the improved Wrec. When x = 0.09, a high recoverable energy density Wrec of 3.83 J/cm3 and a high energy storage efficiency η of 85.7 % were obtained at an electric field of 360 kV/cm. In addition, the 0.91BNKBTZ-0.09SMNT ceramic sample has excellent performance stability under different temperatures (30–180 °C), cycle times (1–104 times) and frequencies (1–100 Hz), making it a reliable candidate as a dielectric for pulsed power systems.