Properties of SrCe0.95M0.05O3 (M = La, Pr, Y, Sn) thermal barrier materials

The lightly doped strontium cerates SrCe0.95M0.05O3, where \M = Pr, Y, La, and Sn, are shown to maintain an invariable Pnma structure at heating in the air up to 1773 K. The decrease in the size of the doping atoms is found to be beneficial for tuning up the thermal expansion coefficient, reducing the average grain size and sinterability of ceramic samples. The doping with large atoms is accompanied by a deterioration in corrosion resistance in the melt of CMAS because of the formation of aluminates and silicates. The tin-doped derivative is not sufficiently stable because of the leaching of tin from the structure. The penetration of the CMAS melt into surface cracks and pores facilitates exfoliation of flakes from the surface, thus contributing to the degradation of cerite ceramics. The combination of small grain size and porosity, optimized thermal expansion, chemical robustness in the melts of CMAS, and high hardness distinguishes SrCe0.95Y0.05O3 as a promising thermal barrier coating material.