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Abstract: As promising TBC (thermal barrier coating) candidates, perovskite oxides own designable properties for their various options of cations and structural diversity, but limited comprehensions of structure‐property relationship delay their engineering applications. In this work, mechanical/thermal properties of ABO3 (A=Sr, Ba; B=Ti, Zr, Hf) perovskites and their anisotropic nature are predicted employing density functional theory. Their theoretical minimum thermal conductivities range from 1.09 to 1.74 W·m−1·K−1, being lower than Y2O3 partially stabilized ZrO2. Reduced thermal conductivities up to 16% along particular directions are reached after considering thermal conductivity anisotropy. All compounds own high hardness while SrZrO3, SrHfO3, and BaHfO3 possess well damage tolerance. We found that small electronegativity discrepancy leads to big anisotropy of chemical bond, Young's/shear moduli and thermal conductivities, together with good damage tolerance. These results suggest that the next generation TBCs with extra low thermal conductivity should be achieved through combining material design and orientation‐growth tailoring. [ABSTRACT FROM AUTHOR]

Rare earth silicates are promising environmental/thermal barrier coating (E/TBC) materials facing severe CMAS (CaO‐MgO‐Al2O3‐SiO2) corrosion. Previous studies mainly focused on the intrinsic properties of precorrosion coatings, but there were few studies on their CMAS corrosion products that play a crucial role in the performance of coatings in postservice stage. In this work, the mechanical and thermal properties of nine corrosion products between lutetium silicates and CMAS are studied using first‐principles calculations. Their differences of elastic stiffness are attributed to the different crystal structures and bonding strength. The T:O ratio is identified as a factor of the crystal structure for silicate products, and it has a good correlation with their elastic stiffness. Moreover, the divergences of thermal conductivity are dominated by three essential factors, that is, atomic vibration intensity, lattice vibrational anharmonicity, and complexity of crystal structure. Compared with rare earth silicates, six products, that is, the α‐CaSiO3, β‐CaSiO3, Ca2MgSi2O7, Ca2Al2SiO7, CaAl2Si2O8, and Ca2Lu8(SiO4)6O2, showing good damage tolerance and low thermal conductivities, are predicted to be advantageous to E/TBCs. These discoveries reveal the mechanical/thermal properties of corrosion products between lutetium silicates and CMAS and are expected to support the future researches on the performance of E/TBC in the postservice stage. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]