Enhanced energy storage properties of (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)(Ti1-Zr )O3 high entropy ceramics by Zr doping at B-site

Due to their interesting properties derived from the high entropy effect, high entropy ceramics (HECs) with perovskite structure are considered promising candidates for energy storage applications. In this paper, lead-free (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)(Ti1-xZrx)O3 (BNCBST-xZr, 0.01 ≤ x ≤ 0.15) HECs were prepared by a hydrothermal technique. The results show that as-prepared samples present a single pseudo-cubic structure, and the Zr doping at the B site of BNCBST provokes lattice distortion and deepens dielectric relaxation. In addition, the grain size is reduced by the incorporation of Zr, leading to the improvement of electrical breakdown strength (Eb). Accordingly, BNCBST-0.05Zr ceramic exhibits optimal energy storage characteristics, as indicated by an excellent recoverable energy density (Wrec) of 3.03 J/cm3 and energy storage efficiency (η) of 84.7% under a great Eb of 307 kV/cm). A wide temperature stability (Wrec and η vary within ±9.3 % and ±1.7 % at 40–100 °C) and short discharge time (100 ns) are also observed in BNCBST-0.05Zr ceramic. These results demonstrates that Zr doping can effectively optimize the Eb as well as the energy storage properties of ceramics, and the prepared BNCBST-0.05Zr HEC is attractive dielectric materials in energy-storage devices.