Abstract:La2Ce2O7 (LC) has been evaluated as one of promising thermal barrier coating candidate ceramic materials due to lower thermal conductivity, better phase stability and larger thermal expansion coefficient than YSZ. However, the thermal expansion coefficients of LC show a sudden drop between 200℃ ~400℃ , which would lead to the formation of thermal stress during thermal cycles and finally resulting in the early failure of the coatings. In recent studies, it has been reported that the sudden drop of the thermal expansion coefficients can be improved by doping with Gd2O3. However, there is little knowledge about the optimum doping content and performances of the coatings. In this paper, (LaxGd1-x)2Ce2O7 (x=0,0.1,0.2,0.3) with single fluorite structure were synthesized by chemical precipitation. The thermal conductivity and phase stability results were compared. (La0.8Gd0.2)2Ce2O7 (LGC) coatings were prepared by plasma spray method. The thermal shock test was performed and its failure mechanism was also studied. The results showed that (La0.8Gd0.2)2Ce2O7 (LGC) had low thermal conductivity and good phase stability from room temperature to 1400 ℃ . Besides, after 100h heat treatment at 1400℃ , there was no phase transformation, indicating high temperature phase stability. Moreover, the corresponding double-ceramic-layer (DCL) LGC /YSZ TBCs had better thermal shock resistance ability than that of LC /YSZ TBCs, which was around 109 cycles at 1200℃ . However, the failure modes was similar to that of LC /YSZ TBCs, which was still layer-by-layer spallation in LGC ceramic layer due to the sintering of the ceramic coating.