Effect of La substitution on energy storage properties of (Bi0.2Na0.2Ca0.2Ba0.2Sr0.2)TiO3 lead‐free high‐entropy ceramics

Abstract In this study, a novel lead‐free high‐entropy ceramic (HEC) system, (Bi 0.2 Na 0.2 Ca 0.2 Ba 0.2 Sr 0.2 ) (1–3 x /2) La x TiO 3 (0 ≤ x ≤ 0.15) (abbreviated as BNCBST‐ x La), was designed to enhance energy storage performance through La substitution and prepared via a hydrothermal method. Results indicate that La doping at A site in BNCBST induces lattice distortion and further improves dielectric relaxation. Moreover, grain growth is inhibited by the La content, which results in an increase in the insulation resistance and thus significant enhancement in the electric breakdown strength ( E b ). Accordingly, the system with x = 0.03 exhibits an excellent recoverable energy density ( W rec ) of 2.43 J/cm 3 and a high energy storage efficiency ( η ) of 85.5% under a great E b of 245 kV/cm, together with wide temperature stability ( W rec and η vary within ± 8.3% and ± 1.1% at 30–150°C). The findings of this study suggest that the obtained La‐modified BNBCST HECs are promising for energy storage applications.