Structure, dielectric, and relaxor properties of BaTiO₃-modified high-entropy (Bi_0.2Na_0.2K_0.2Ba_0.2Ca_0.2)TiO₃ ceramics for energy storage applications

High-entropy (1−x)Bi_0.5Na_0.5K_0.5Ba_0.5Ca_0.5TiO₃-xBaTiO₃ (BNKBCT-BT, x = 0.02, 0.06, 0.10, 0.14 and 0.20) ceramics are successfully prepared via the solid-state reaction method. The XRD and Raman analyses reveal that all samples exhibit a pseudo-cubic phase structure. With increasing x, the a is gradually increased, resulting in the expansion of unit cell volume. A strong frequency dispersion appeared around T_m, demonstrating that the as-prepared ceramics is a relaxor ferroelectric. Owing to the increase in the degree of lattice disorder, as well as relaxation and thermal evolution of PUs, the as-prepared ceramics exhibit a broad relaxor behavior. The ΔP is effectively increased by doping BT, which is conducive to achieving excellent energy storage properties. Moreover, W_rec of all samples is more than 1.31 J/cm³ and, at x = 0.20, W_rec reaches the maximum value of 2.24 J/cm³ at 140 kV/cm. These results indicate that high-entropy (1−x)BNKBCT-xBT ceramics are promising materials for energy storage applications.