Single-phase formation mechanism and dielectric properties of sol-gel-derived Ba(Ti_0.2Zr_0.2Sn_0.2Hf_0.2Ce_0.2)O₃ high-entropy ceramics

Single-phase Ba(Ti_0.2Zr_0.2Sn_0.2Hf_0.2Ce_0.2)O₃ (BTZSHC) high-entropy ceramics (HECs) with the perovskite structure were successfully prepared via the sol-gel method. The results reveal that the as-prepared ceramics exhibit a single cubic phase belonging to the Pm3¯m space group. The high entropy is the driving force of the formation of single-phase ceramics. A larger entropy (ΔS_mix) and a negative enthalpy (ΔH_mix) are conducive to the formation of single-phase compounds. Herein, ΔS_mix = 0.323R mole^–1 and ΔH_mix = −43.88 kJ/mol. The sluggish-diffusion effect ensures the thermal stability of high-entropy systems. Dielectric measurements reveal that the as-prepared BTZSHC high-entropy ceramics are relaxor ferroelectrics, and the degree of relaxor (γ) is 1.9. The relaxor behavior of the as-prepared ceramics can be ascribed to the relaxation and thermal evolution of their polar units (PUs). The findings of this work provide a theoretical basis and technical support for the preparation of single-phase high-entropy ceramics.