Synthesis and thermophysical properties of RETa 3 O 9 (RE = Ce, Nd, Sm, Eu, Gd, Dy, Er) as promising thermal barrier coatings

Abstract Thermal barrier coatings (TBCs) are one of the most important materials in gas turbine to protect the high temperature components. RETa 3 O 9 compounds have a defect‐perovskite structure, indicating that they have low thermal conductivity, which is the critical property of TBCs. Herein, dense RETa 3 O 9 bulk ceramics were fabricated via solid‐state reaction. The crystal structure was characterized by X‐ray diffraction (XRD) and Raman Spectroscope. Scanning electron microscope (SEM) was used to observe the microstructure. The thermophysical properties of RETa 3 O 9 were studied systematically, including specific heat, thermal diffusivity, thermal conductivity, thermal expansion coefficients, and high‐temperature phase stability. The thermal conductivities of RETa 3 O 9 are very low (1.33‐2.37 W/m·K, 373‐1073 K), which are much lower than YSZ and La 2 Zr 2 O 7 ; and the thermal expansion coefficients range from 4.0 × 10 −6 K −1 to 10.2×10 −6 K −1 (1273 K), which is close to La 2 Zr 2 O 7 and YSZ. According to the differential scanning calorimetry (DSC) curve there is not phase transition at the test temperature. Due to the high melting point and excellent high‐temperature phase stability with these oxides, RETa 3 O 9 ceramics were promising candidate materials for TBCs.