Interfacial Stability between High-Entropy (La 0.2 Yb 0.2 Sm 0.2 Eu 0.2 Gd 0.2) 2 Zr 2 O 7 and Yttria-Stabilized Zirconia for Advanced Thermal Barrier Coating Applications.

(La_0.2Yb_0.2Sm_0.2Eu_0.2Gd_0.2)₂Zr₂O₇ (HEZ) has shown considerable promise as a novel thermal barrier coating material for temperatures exceeding 1300 °C. This study systematically investigates the interfacial stability of (La_0.2Yb_0.2Sm_0.2Eu_0.2Gd_0.2)₂Zr₂O₇ with yttria-stabilized zirconia (YSZ), which is of paramount importance for its application in double-layer thermal barrier coatings. Our findings highlight that rare earth elements with a smaller radius diffuse more easily into the YSZ lattice, resulting in a broader diffusion zone. Simultaneously, the incorporation of rare earth elements into the YSZ lattice inhibits tetragonal-to-monoclinic phase transformation. Compared to La₂Zr₂O₇/YSZ, HEZ/YSZ demonstrates superior high-temperature stability, which could be attributed to the higher fracture toughness and lower thermal expansion coefficient of HEZ, the absence of t-m transformation and the formation of a continuous gradient diffusion layer that minimizes interface stress. This study offers a practical strategy for designing materials for durable double-layer thermal barrier coating systems. [ABSTRACT FROM AUTHOR]