High-entropy engineering improved the corrosion resistance of rare earth tantalates

High-entropy RETa 3 O 9 ceramics have garnered significant interest in materials science due to their impressive high melting points and lower thermal conductivity. This study focuses on three types of these ceramics: (La 0.2 Ce 0.2 Nd 0.2 Sm 0.2 Dy 0.2 )Ta 3 O 9 , (La 0.2 Ce 0.2 Nd 0.2 Sm 0.2 Tm 0.2 )Ta 3 O 9 , and SmTa 3 O 9 .The results indicate that the coefficient of thermal expansion (TEC) for RETa3O9 ceramics remains in the range of approximately 5.94 × 10 −6 K -1 to 6.05 × 10 −6 K -1 when subjected to temperatures from room temperature up to 1400 °C. This TEC is notably similar to that of silicon carbide ceramic matrix composites (SiC-CMC), which is essential for compatibility in applications where these materials are used together. Moreover, the study highlights an important finding: after 20 h of exposure to a CMAS (calcium-magnesium-alumino-silicate) environment at 1300 °C, the high-entropy tantalates exhibit significantly reduced susceptibility to corrosion compared to traditional single-component tantalate ceramics. While single-component materials, including SmTa3O9, showed greater degradation, the high-entropy RETa3O9 ceramics maintained their original morphology, free from porosity and cracking. This impressive resistance to CMAS corrosion indicates that the high-entropy design is beneficial in enhancing the durability of tantalates in extreme environments. Consequently, these findings suggest that high-entropy RETa3O9 ceramics hold promise for use as thermal/environmental barrier coating (T/EBC) materials in applications involving SiC-CMCs, potentially leading to improved performance and longevity in high-temperature applications.