Single-phase formation mechanism and dielectric properties of sol-gel-derived Ba(Ti0.2Zr0.2Sn0.2Hf0.2Ce0.2)O3 high-entropy ceramics

Single-phase Ba(Ti0.2Zr0.2Sn0.2Hf0.2Ce0.2)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 (ΔSmix) and a negative enthalpy (ΔHmix) are conducive to the formation of single-phase compounds. Herein, ΔSmix = 0.323R mole–1 and ΔHmix = −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.