RE₂Si₂O₇ is promising materials for environmental barrier coating (EBC), but the vast phase space poses challenges for the screening of RE₂Si₂O_7. It follows that a combined approach of first principles calculations and machine learning is proposed for this problem, with establishing a comprehensive database comprising β-, γ- and δ-RE₂Si₂O₇ (RE = La–Lu, Y, Sc) and correlating their mechanical/thermal properties on structural characteristics. It is revealed the [O₃SiOSiO₃] structure and polyhedron distortion affect mechanical properties of RE₂Si₂O₇, while criteria for selecting RE₂Si₂O₇ with low thermal conductivity are identified, including complex crystal structures, chemical bond inhomogeneity, and strong non-harmonic lattice vibrations. Also, the machine learning model accurately predicts the coefficient of thermal expansion (CTE) and minimum thermal conductivity (λ_min) of RE₂Si₂O₇, with volume and mass variations identified as critical factors, respectively. This integrated approach efficiently screens RE₂Si₂O₇ for EBC application and enables rapid assessments of their thermal properties.

The atomic structural features and the mechanical properties of amorphous silicoboron carbonitride ceramics with 13 different compositions in the Si–BN–C phase diagram are investigated employing ab-initio calculations. Both chemical bonds and local structures within the amorphous network relate to the elemental composition. The distribution of nine types of chemical bonds is composition-dependent, where the B–C, Si–N, Si–C, and B–N bonds hold a large proportion for all compositions. Si prefers to be tetrahedrally coordinated, while B and N prefer sp²-like trigonal coordination. In the case of C, the tetrahedral coordination is predominant at relatively low C contents, while the trigonal coordination is found to be the main feature with the increasing C content. Such local structural characteristics greatly influence the mechanical properties of SiBCN ceramics. Among the studied amorphous ceramics, SiB₂C₃N₂ and SiB₃C₂N₃ with low Si contents and moderate C and/or BN contents have high elastic moduli, high tensile/shear strengths, and good debonding capability. The increment of Si, C, and BN contents on this basis results in the decrease of mechanical properties. The increasing Si content leads to the increment of Si-contained bonds that reduce the bond strength of SiBCN ceramics, while the latter two cases are attributed to the raise of sp²-like trigonal configuration of C and BN. These discoveries are expected to guide the composition-tailored optimization of SiBCN ceramics.

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.

Gadolinium zirconate (GZ) is a promising candidate for next-generation thermal barrier coating (TBC) materials. Its corrosion resistance against calcium–magnesium–alumino–silicate (CMAS) needs to be further increased for enhancing its in-service life. As the Gd element plays an important role in the CMAS resistance, three GZ coatings (GZ-0.75, GZ-1.0, and GZ-1.2) with different Gd/Zr atomic ratios are designed and deposited by laser enhanced chemical vapor deposition (LCVD) in this work. It is found that the generated Gd-apatite in GZ-1.2 would block micro-cracks inside the column structure and the inter-columnar gap more efficiently. Thus, the CMAS penetration rate (5.2 μm/h) of GZ-1.2 decreases over 27% comparing with GZ-1.0 and GZ-0.75, which is even lower than the Gd₂Zr₂O₇ coatings fabricated by electron-beam physical vapor depositions (EB-PVDs). This work provides a feasible way to adjust the coating’s corrosion resistance and may guide the development of future coating for long in-service life.