Preparation and water vapor corrosion behavior of high entropy rare earth disilicate (Y0.25Yb0.25Ho0.25Er0.25) 2Si2O7

In this work, a new type of high-entropy rare earth disilicate, denoted as (Y0.25Yb0.25Er0.25Ho0.25)2Si2O7 or simply (4RE0.25)2Si2O7 ceramic was synthesized using the sol-gel method. Its excellent resistance to water vapor corrosion was demonstrated. The results revealed that the high-entropy (4RE0.25)2Si2O7 exhibited consistent physical and chemical properties from room temperature to 1400 °C, as indicated by TG-DSC analysis. Moreover, the coefficient of thermal expansion (CTE) of (4RE0.25)2Si2O7 measured 3.95 × 10−6 K-1, which closely resembled that of SiCf/SiC composites. Notably, the weight loss of the bulk (4RE0.25)2Si2O7 was a mere 0.056 %, showcasing its superior performance compared to Yb2Si2O7 ceramics. As a result, the novel (4RE0.25)2Si2O7 ceramic holds promise for enhancing the water vapor corrosion resistance of SiCf/SiC composites, whether employed as coatings or matrices.