Insights into structural, mechanical and thermal properties of high-entropy ceramic (Sc 0.25 Ce 0.25 Gd 0.25 Er 0.25 ) 2 Zr 2 O 7 : ab initio and experimental studies

Abstract This work reports a single-phase high-entropy zirconate (Sc 0.25 Ce 0.25 Gd 0.25 Er 0.25 ) 2 Zr 2 O 7 , and reveals the atomic-scale mechanisms governing its superior mechanical and thermal properties via a combined first-principles and experimental approach. The material adopts a stable defect-fluorite structure with uniform elemental distribution and pronounced local lattice distortion. Atomic displacement is especially notable around smaller cations such as Zr 4+ and Sc 3+ . Bond length distributions and charge density analysis reveal a heterogeneous bonding environment, where strong directional Sc–O bonds enhance elastic modulus and Debye temperature, while weaker Ce–O interactions promote phonon scattering and thermal expansion. The experimental validation confirms high thermal expansion coefficient (11.99 × 10 −6 K −1 , 300 K—1773 K), low thermal conductivity, and good damage tolerance. These findings highlight the critical role of configurational disorder and bonding heterogeneity in tuning materials properties and offer a foundation for designing advanced ceramic for demanding thermal barrier coating applications.