Thermo-physical and mechanical properties of Yb2O3 and Sc2O3 co-doped Gd2Zr2O7 ceramics

Ceramic materials for the thermal barrier coating (TBC) application of Gd 2 Zr 2 O 7 (GZO), (Gd 0.94 Yb 0.06 ) 2 Zr 2 O 7 (GYb 0.06 Z), (Gd 0.925 Sc 0.075 ) 2 Zr 2 O 7 (GSc 0.075 Z), (Gd 0.865 Sc 0.075 Yb 0.06 ) 2 Zr 2 O 7 (GSc 0.075 Yb 0.06 Z), and (Gd 0.8 Sc 0.1 Yb 0.1 ) 2 Zr 2 O 7 (GSc 0.1 Yb 0.1 Z) were successfully synthesized by chemical co-precipitation. The effects of the doping of Sc 2 O 3 and Yb 2 O 3 on the phases, thermo-physical and mechanical properties of the ceramics were investigated. The results show that both Yb 2 O 3 and Sc 2 O 3 doping promoted the phase transition of GZO from pyrochlore to fluorite. All the Sc 2 O 3 -doped samples exhibited enhanced fracture toughness, as compared to the undoped sample. Furthermore, the GSc 0.075 Yb 0.06 Z sample revealed a thermal conductivity of ~0.8 W/mK at 1200 °C, which was nearly 30% lower than that of the undoped sample. The associated mechanisms related to the effects of the doping on the thermophysical and mechanical properties are discussed.