Structure and thermal properties of SrCe1-xSnxO3 (x=0.1 ... 0.5) as a promising thermal barrier coating.

Gas turbines efficiency growth is primarily associated with an increase in the operating temperature of the combustion chamber, which places new stringent requirements on the materials of thermal barrier coatings. Strontium cerate doped with tin SrCe 1- x Sn x O 3 where x = 0.1 ... 0.5, was proposed as a promising material. The research has shown that the lightly doped solid solution SrCe 1-x Sn x O 3 has an orthorhombic Pnma structure at x < 0.3, whereas at a high content of Sn4+ the monoclinic structure P2 1 /m becomes more favorable. Thermogravimetric analysis (TGA) in reducing atmosphere (5%H 2 in Ar) shows no mass lost as a result of unchangeable charge of Ce4+ and Sn4+. An increase in the distortion of the crystal lattice, due to the large difference in the ionic radii of Ce4+ and Sn4+, leads to a deterioration in the symmetry of the crystal lattice, a reduction of thermal conductivity (from 1.9 to 1.4 W m−1 K−1 at 1000 °C) and at the same time, growth of hardness and porosity. The increase in porosity, along with an increase in the required temperature of solid-state synthesis, indicates an enhancement in the melting point of the obtained materials. For the compounds with an orthorhombic structure, the thermal expansion coefficient increases with a growth in the Sn content, achieving a highest point 12.47·10−6 K−1 at 1100 °C for x = 0.3. The combination of the revealed properties and their comparison with advanced refractories makes the solid solution, primarily SrCe 0.5 Sn 0.5 O 3 , a promising material for application as thermal barrier coatings. [ABSTRACT FROM AUTHOR]