Unveiling elastic and thermal properties of Nd-rich high-entropy zirconate by experiments and ab initio calculations

High-entropy ceramics have recently emerged as promising candidates for advanced thermal-barrier-coating applications due to their exceptional tunability and thermal stability. In this work, the phase stability, elastic behavior and thermal performance of a non-equimolar high-entropy zirconate (Nd 0.4 Ce 0.15 Sm 0.15 Eu 0.15 Yb 0.15 ) 2 Zr 2 O 7 are systematically investigated through ab initio calculations based on the special quasi-random structure approach, and validated by complementary experimental characterizations. The material preferentially crystallizes into a pyrochlore-type structure, with sharp diffraction peaks and uniform elemental distribution confirming its crystallinity and compositional homogeneity. The elastic behavior is analyzed by single-crystal and polycrystalline elastic moduli using a series of phenomenological models. The broad distribution of metal-nonmetal bond lengths highlights large distortion fluctuations, which strongly influence the intrinsic materials parameters. The material exhibits high Vickers hardness (18.2 GPa) and thermal expansion coefficient (11.77 × 10 -6 K -1 at 1773 K), exceeding that of pristine Nd 2 Zr 2 O 7 and conventional yttria-stabilized zirconia. Additionally, the severe lattice distortion induces strong phonon scattering, resulting in low thermal conductivity (1.16 W⋅m -1 ⋅K -1 at 1773 K). The integrated theoretical-experimental study provides critical insights for the rational design of high-entropy materials for extreme-temperature applications.