(Y0.05La0.95)2(Zr0.7Ce0.3)2O7 ceramics as a thermal barrier coating material for high-temperature applications

Abstract Oxide ceramics with stable phase structure, good thermophysical properties and high sintering-resistance above 1473 K have very important applications in thermal barrier coatings (TBCs). The (Y 0.05 La 0.95 ) 2 (Zr 0.7 Ce 0.3 ) 2 O 7 (YLZC) ceramics were synthesized by solid state reaction at 1673 K for 24 h in air. The phase stability, thermophysical properties and sintering-resistance behavior of YLZC ceramics were investigated in detail. The YLZC ceramics consist of mixture structures of pyrochlore and fluorite, and no new phase appears after long-term annealing. Thermal expansion coefficient of YLZC is about 10.58×10 −6 K −1 , which is larger than that of La 2 Zr 2 O 7 (LZ) (9.18×10 −6 K −1 ) and similar to that of La 2 (Zr 0.7 Ce 0.3 ) 2 O 7 (LZC) (10.53×10 −6 K −1 ). The thermal conductivities of the YLZC ceramics first decrease gradually with the increase of temperature below 1273 K and then increase slightly above 1273 K. The minimum value of ~0.86 W m −1 K −1 is gained at 1273 K. The volume shrinkages of LZC and YLZC are basically identical, only a bit of improvement in sintering-resistance is observed at 1873 K.