Enhancing Thermal Insulation Performance through Entropy Stabilization in Rare-Earth Zirconate Structures

Thermal barrier coating (TBC) materials utilize ceramics with low thermal conductivity and exceptional thermal durability. The gas turbine market has recently seen a growing demand for thermally insulating materials suitable for operating temperatures exceeding 1200 °C, achieved aiming greater thermal conversion efficiency. In this study, we synthesized high-entropy A₂Zr₂O₇ zirconate ceramics by incorporating five cations of similar ionic radius into the A³⁺ cation site through a conventional solid-state reaction, and we demonstrated their superior thermophysical properties. The high-entropy oxide (HEO) ceramics exhibited consistently low thermal conductivity, ranging from room temperature to 1000 °C, mainly due to lattice distortion induced in the crystal structure. Furthermore, we introduced divalent cations to the A³⁺ cation site to increase oxygen vacancies within the structure, thereby reducing heat transfer caused by phonons. These A₂Zr₂O₇ zirconate HEOs demonstrate improved thermal barrier performance compared to yttria-stabilized zirconia (YSZ), which is a conventional TBC material. This highlights their potential application as next-generation TBC materials.