Preparation and characterization of (Yb_0.25Lu_0.25Sc_0.25Tm_0.25)2Si₂O₇ as a potential environmental barrier coating

A novel high-entropy rare-earth disilicate (Yb0.25Lu0.25Sc0.25Tm0.25)(2)Si2O7 ((4RE(0.25))(2)Si2O7) was proposed as an advanced environmental barrier coating (EBC) materials in this work. The (4RE(0.25))(2)Si2O7 powders were synthesized using the solid-state sintering method. Based on the X-ray diffraction (XRD) and scanning electron microscope/energy-dispersive spectroscopy analysis, the uniform solid solution was detected in the (4RE(0.25))(2)Si2O7, which had a monoclinic beta-phase structure in the space group of C2/m. The lattice parameter of the structure was derived based on the Rietveld refinement analysis to the XRD results. The coefficient of thermal expansion of the bulk (4RE(0.25))(2)Si2O7 was similar to that of the SiC-SiC ceramic matrix composite substrate of the environmental barrier coating. In addition, this (4RE(0.25))(2)Si2O7 bulk material had a very low thermal conductivity, which was beneficial for the application of environmental barrier coatings. The hot water-vapor corrosive experiments were conducted in an environment of 90% air and 10% H2O at 1300(degrees)C. The results indicated a better water-vapor corrosion performance than the commercialized Yb2Si2O7 EBC materials. The (4RE(0.25))(2)Si2O7 material prepared in this work showed great potential to work as the environmental barrier coating.