Thermophysical Properties of Complex Rare‐Earth Zirconate Ceramic for Thermal Barrier Coatings

Two complex rare‐earth zirconates (La 0.4 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.4 and (Sr 0.1 La 0.3 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.3 for thermal barrier coatings (TBCs) were synthesized by the coprecipitation method. Their phase composition, microstructure, and thermophysical properties were investigated. X‐ray diffractometry results revealed that single‐phase (La 0.4 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.4 and (Sr 0.1 La 0.3 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.3 with pyrochlore structure were prepared, and the scanning electron microscopy results showed that the microstructures of the products were dense and no other phases existed among the grains. With the temperature increasing, the thermal expansion coefficient (CTE) of the ceramics increased, while the thermal conductivity decreased. The results indicated that the CTE of (Sr 0.1 La 0.3 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.3 was slightly higher than that of (La 0.4 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.4 and the thermal conductivity of (Sr 0.1 La 0.3 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.3 was lower than that of (La 0.4 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.4 . These results imply that the thermophysical properties of (Sr 0.1 La 0.3 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.3 are better than that of (La 0.4 Sm 0.5 Yb 0.1 ) 2 (Zr 0.7 Ce 0.4 ) 2 O 7.4 as the material for the ceramic layer in the TBC system.