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 (Y 0.25 Yb 0.25 Er 0.25 Ho 0.25 ) 2 Si 2 O 7 or simply (4RE 0.25 ) 2 Si 2 O 7 ceramic was synthesized using the sol-gel method. Its excellent resistance to water vapor corrosion was demonstrated. The results revealed that the high-entropy (4RE 0.25 ) 2 Si 2 O 7 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 (4RE 0.25 ) 2 Si 2 O 7 measured 3.95 × 10 −6  K -1 , which closely resembled that of SiC f /SiC composites. Notably, the weight loss of the bulk (4RE 0.25 ) 2 Si 2 O 7 was a mere 0.056 %, showcasing its superior performance compared to Yb 2 Si 2 O 7 ceramics. As a result, the novel (4RE 0.25 ) 2 Si 2 O 7 ceramic holds promise for enhancing the water vapor corrosion resistance of SiC f /SiC composites, whether employed as coatings or matrices.