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Page 2 of 17 Zhang et al. J. Mater. Inf. 2026, 6, 11

Interestingly, theoretical predictions indicate slightly higher intrinsic K IC in RE 2 Zr 2 O 7 , which is attributed to its ordered
vacancy sublattice and symmetric bonding. In contrast, experimental data often report superior K IC for RE 3 TaO 7 , likely
due to extrinsic microstructural effects not captured in idealized calculations. Correlation and SHapley Additive
exPlanations analyses further reveal that bond energy, charge disorder and bond-length heterogeneity are key
descriptors governing κ L and K IC . These findings provide mechanistic insight into structure–property relationships
and offer a predictive framework for the rational design of RE oxide TBC materials.

Highlights
• Integrating high-throughput first-principles calculations, lattice-level descriptor engineering and interpretable
machine learning to design RE 2 Zr 2 O 7 and RE 3 TaO 7 (RE = Sc, Y, La ~ Lu) oxide-based thermal barrier materials.
• Data-driven selection and classification of key physical descriptors (bond energy, charge disorder, bond-length
heterogeneity) enable predictive modeling of κ L and K IC across 17 rare-earth elements.
• Combining thermodynamic stability analysis, phonon-based transport models and SHapley Additive exPlanations
interpretability to establish structure–property relationships and guide rational oxide design.

INTRODUCTION
Advancing the performance and reliability of thermal barrier coatings (TBCs) represents a persistent
challenge in the development of next-generation high-temperature materials, particularly for demanding
applications in aerospace propulsion and energy conversion systems . The continuous push toward higher
[1-3]
operational temperatures and harsher service environments necessitates the discovery and design of ceramic
materials that not only exhibit ultralow lattice thermal conductivity (κ ) for efficient thermal insulation but
L
also possess robust mechanical stability, exemplified by high fracture toughness (K ), along with enhanced
IC
resistance to environmental degradation . However, conventional yttria-stabilized zirconia (YSZ), currently
[4,5]
the industry standard, faces intrinsic limitations above 1,473 K, primarily due to phase instability and
accelerated degradation mechanisms . Consequently, exploring alternative ceramic systems with superior
[6,7]
thermomechanical performance at elevated temperatures is of critical importance.

Rare-earth (RE)-based oxide ceramics, particularly RE zirconates and tantalates, have emerged as promising
alternative candidates, owing to their intrinsically low thermal conductivity, high melting points, and
exceptional structural stability at elevated temperatures [8-12] . Furthermore, the compositional flexibility
afforded by substituting and doping various RE elements enables precise tuning of lattice parameters and
phonon scattering characteristics, significantly optimizing their thermal and mechanical properties. Recently,
high-entropy oxides (HEOs), characterized by multicomponent RE element incorporation, have attracted
considerable attention due to their unique capacity for simultaneously achieving ultralow thermal
conductivity and enhanced K , driven by severe lattice distortions and increased chemical disorder [13-15] .
IC
Nevertheless, despite these promising attributes, the complexity introduced by a large compositional space
and numerous potential element combinations presents a significant obstacle to systematic optimization.
This complexity necessitates an efficient and systematic approach to elucidate the influence of each RE
element on thermomechanical performance and to identify optimal compositions.

Recent studies have demonstrated that κ and K of ceramic TBC materials are strongly influenced by
L
IC
atomic-scale structural characteristics, such as crystal lattice symmetry [16-18] , oxygen vacancy
concentration [19,20] , local lattice distortion [21-24] , and the nature of chemical bonding [25-27] . Reduced thermal
conductivity is primarily achieved through enhanced phonon scattering mechanisms, typically arising from
structural disorder, lattice anharmonicity, point defects, and atomic mass mismatch introduced via
compositional complexity [21,28-30] . For example, previous investigations demonstrated that structurally
complex phases, such as defect fluorite and pyrochlore structures, effectively enhance phonon scattering,