Investigation of thermophysical properties and elastic moduli of Sm₂GdTa_1-xCe_xO_7-x/2 oxides for thermal barrier coatings

In this study, Sm₂GdTa_1-xCe_xO_7-x/2 compounds were synthesized by adopting a high-temperature sintering technology and selecting highly purified Sm₂O₃, Gd₂O₃, CeO₂, and Ta₂O₅ as origin chemicals. The crystal lattice, microstructure, element composition, thermophysical performances, and elasticity moduli of the compounds were investigated. Results indicate that the maintained compounds have a single pyrochlore lattice, and the relative densities exceed 92 %. Their coefficients of thermal expansion are elevated with incremental CeO₂ fraction due to the greater ionic radius of Ce⁴⁺ than that of Ta⁵⁺.The thermal conductivities of Sm₂GdTa_1-xCe_xO_7-x/2 compounds are reduced because of phonon scattering caused by substituting atoms and oxygen vacancies. However, their thermal conductivities at high temperatures are higher than values of limit thermal conductivities, indicating that their thermal conductivities can be reduced further. These synthesized compounds also show excellent crystal lattice stability until 1200 °C.