Lattice engineering via large-radius cation doping: A novel strategy for CMAS-resistant high-entropy (Nd0.2Y0.2Er0.2Yb0.2Lu0.2)2SiO5

Three high-entropy silicates were synthesized: (Y 0.25 Er 0.25 Yb 0.25 Lu 0.25 ) 2 SiO 5 (4HE), (Nd 0.2 Y 0.2 Er 0.2 Yb 0.2 Lu 0.2 ) 2 SiO 5 (NdHE), and (La 0.2 Y 0.2 Er 0.2 Yb 0.2 Lu 0.2 ) 2 SiO 5 (LaHE)，with systematic analysis of size disorder effects on crystal structure and phase composition. Using Y 2 SiO 5 as a control, the corrosion resistance of these rare earth silicates was compared, and the influence of La 3 + and Nd 3+ doping on CMAS corrosion was analyzed. The research results demonstrate that La doping induces the formation of 7.51 wt% X1 phase due to high size disorder (δ = 0.0854), whereas NdHE maintains a nearly single-phase X2-type structure. NdHE exhibits the optimal CMAS corrosion resistance in isothermal CMAS corrosion experiments conducted at both 1400 ℃ and 1500 ℃. This is attributed to Nd 3+ doping accelerating the precipitation of apatite-phase corrosion products and altering their growth orientation, thereby enabling rapid formation of a continuous, dense corrosion layer at the melt-substrate interface, which effectively impedes further rapid penetration of CMAS.