Orthorhombic perovskite oxides are studied by high-throughput first-principles calculations to explore new thermal barrier coating (TBC) materials with low thermal conductivities. The mechanical and thermal properties are predicted for 160 orthorhombic perovskite oxides. The average atomic volume is identified as a possible predictor of the thermal conductivity for the perovskite oxides, as it has a good correlation with the thermal conductivity. Five compounds, i.e., LaTmO3, LaErO3, LaHoO3, SrCeO3, and SrPrO3, having thermal conductivities under 1 W·m−1·K−1 and good damage tolerance, are proposed as novel TBC materials. The obtained data are expected to inspire the design of perovskite oxide-based TBC materials and also support their future functionality investigations.

Thermal barrier coatings (TBCs) play an important role in gas turbines to protect the turbine blades from the high‐temperature airflow damage. In this work, we use first‐principles calculations to investigate a specific class of rare‐earth (RE) aluminates, including cubic‐REAlO3 (c‐REAlO3), orthorhombic‐REAlO3 (o‐REAlO3), RE3Al5O12, and RE4Al2O9, to predict their structural stability, bonding characteristics, and mechanical and thermal properties. The polyhedron structures formed by the Al–O bonds are stronger and exhibit rigid characteristics, whereas the polyhedra formed by the RE–O bonds are relatively weak and soft. The alternating stacking of AlO4 tetrahedra, AlO6 octahedra, and RE–O polyhedra, as well as the selection of RE elements, shows intensive influences on the expected mechanical and thermal properties. The B, G, and E of these four types of aluminates decrease in the order of c‐REAlO3 > o‐REAlO3 > RE3Al5O12 > RE4Al2O9. REAlO3 and RE4Al2O9 are brittle and quasi‐ductile ceramics, respectively, whereas RE3Al5O12 is tailorable. The minimum thermal conductivity is in the range of 1.4–1.5 W m−1 K−1 for c‐REAlO3, 1.3–1.4 W m−1 K−1 for o‐REAlO3, 1.25–1.35 W m−1 K−1 for RE3Al5O12, and 0.8–0.9 W m−1 K−1 for RE4Al2O9. RE4Al2O9 with low thermal conductivity and damage tolerance is predicted to be the potential candidates for next‐generation TBC materials.

RE2SiO5 (RE = Yb and Lu) are significant environmental barrier coating (EBC) materials, in which surface and oxygen vacancy play crucial roles in their structural stability and functionality. In this work, the structural configuration and thermodynamics of (1 0 0), (0 1 0), and (0 0 1) surfaces of RE2SiO5 are investigated by first‐principles calculations. The (0 0 1) surface is preferred energetically, which is attributed to the weak bond broken environment and large rare‐earth polyhedron distortion on this surface. Moreover, the formation energies of various oxygen vacancies on the stable (0 0 1) surface are estimated and the optimal location for oxygen vacancies is held by the [SiO4] tetrahedron. The oxygen vacancies are more likely to segregate on the surface because of the lower formation energies on the surfaces compared with those in the bulk. These findings are expected to enable the development of RE2SiO5‐based EBCs by tuning grain size and/or thin film growth orientation.