Thermal barrier coatings (TBCs) are applied on the critical components of gas turbine engine to insulate the thermal conduction and prolong the lifetime of metallic component. [1][2][3] Calcium-magnesium-alumino-silicates (CMAS) corrosion of TBCs has become more critical with the increase in engineoperating temperature. [4][5][6][7] CMAS arises from the volcanic ash, dust, and fine sand in the intake air, which will deposit on the surface of the TBCs during engine operation, finally form a CMAS melt when temperature exceeds the melting point, 1200°C-1250°C. 5,8 For the state-of-the art 7-8 wt% yttria stabilized zirconia (7-8YSZ) TBCs, CMAS melt could rapidly dissolve the YSZ and dispersively reprecipitate yttrialean zirconia at elevated temperature, which directly destroys the microstructural integrity of the top coat. 9,10 Additionally, CMAS melt, driven by the capillary force, 11 will fill the open pores of YSZ top coat at elevated temperature, and coagulate during cooling which severely stiffen the top coat and degrades the strain tolerance of TBCs. 7,[12][13][14] To mitigate the CMAS attack, one promising strategy is to develop new CMAS-resistant TBCs materials. 5 Generally, these materials should have high reactivity with CMAS melt. 5,15 The classical CMAS-resistant thermal barrier oxides are rare earth (RE) zirconates, e.g., RE 2 Zr 2 O 7 and RE 4 Zr 3 O 12 , [16][17][18][19] which can react with CMAS and rapidly precipitate a dense reaction products layer at the reaction front. The formation of dense reaction layer mitigates further CMAS infiltration, therefore exhibits a much better CMAS resistance in RE zirconates compared with 7-8YSZ.