γ-type high-entropy disilicates (Y_0.2Er_0.2Tm_0.2Yb_0.2X_0.2)₂Si₂O₇ (X = Dy, Gd, Ho): Phase stability, thermal behavior, and CMAS corrosion resistance

Three quinary high entropy disilicate (HEDS) compositions namely, (Y_0.2Er_0.2Tm_0.2Yb_0.2Dy_0.2)₂Si₂O₇, (Y_0.2Er_0.2Tm_0.2Yb_0.2Gd_0.2)₂Si₂O₇ and (Y_0.2Er_0.2Tm_0.2Yb_0.2Ho_0.2)₂Si₂O₇ were synthesized via ball milling and sintering using commercially available oxides for environmental barrier coating (EBC) applications. XRD, SEM, and EDS analyses confirmed the formation of single-phase γ-type pyrosilicates with dense and homogenous elemental distribution. Moreover, it was found that the newly developed (5RE_0.2)₂Si₂O₇ high entropy disilicate materials exhibit low thermal conductivities, high temperature phase stability and similar coefficients of thermal expansion (CTE) with SiC. CMAS corrosion resistances of HEDS samples were investigated at 1300 °C for 2, 12, and 24 h. The findings highlight the potential of high entropy engineering to enhance the high-temperature corrosion resistance, high temperature phase stability and improved thermal properties making these materials promising candidates for advanced EBC systems for gas turbine applications.