(Gd0.2Ho0.2Er0.2Yb0.2Lu0.2)2Si2O7 and (Sc0.2Ho0.2Er0.2Yb0.2Lu0.2)2Si2O7 high-entropy rare-earth disilicates as promising materials for environmental barrier coatings.

The novel potential environmental barrier coating materials, two high-entropy rare earth disilicates (HEDs) (Gd 0.2 Ho 0.2 Er 0.2 Yb 0.2 Lu 0.2) 2 Si 2 O 7 and (Sc 0.2 Ho 0.2 Er 0.2 Yb 0.2 Lu 0.2) 2 Si 2 O 7 were prepared by the solid-phase method. Both the HEDs showed remarkable high-temperature phase stability and an appropriate thermal expansion coefficient (CTE) that matched that of SiC f /SiC. In addition, both the HEDs possessed above 20% lower thermal conductivity at 1000 °C (1.37 and 1.42 W·m−1·K−1, respectively) compared to traditional single-component rare earth disilicate material YbDS, and they also exhibited higher mechanical properties and good resistance to water vapour corrosion at 1300 °C. Moreover, the corresponding free-standing coatings obtained after deposition by atmospheric plasma spraying (APS) showed excellent resistance to CMAS corrosion, primarily because of the formation of an apatite layer. [ABSTRACT FROM AUTHOR]