Enhanced high-temperature performance of selected high-entropy rare earth disilicates

First-principles calculations were utilized to evaluate the synthesis feasibility of (Yb_0.2Y_0.2Lu_0.2Ho_0.2Er_0.2)₂Si₂O₇, (Yb_0.2Tm_0.2Lu_0.2Sc_0.2Er_0.2)₂Si₂O₇, (Yb_0.2Tm_0.2Lu_0.2Sc_0.2Gd_0.2)₂Si₂O₇, and (Yb_0.2Y_0.2Lu_0.2Sc_0.2Gd_0.2)₂Si₂O₇, followed by their fabrication using the solid-phase reaction method. This study investigates the thermal properties of four novel high-entropy rare earth disilicates and compares them with Yb₂Si₂O₇, a material known for its high-temperature stability. The aim was to explore the influence of high configurational entropy and small grain size on enhancing material properties that are critical in high-temperature applications. Key findings demonstrated that these high-entropy materials exhibit lower thermal conductivity, higher specific heat capacity, an0d reduced coefficient of thermal expansion compared to Yb₂Si₂O₇. Among them, (Yb_0.2Tm_0.2Lu_0.2Sc_0.2Er_0.2)₂Si₂O₇ and (Yb_0.2Y_0.2Lu_0.2Ho_0.2Er_0.2)₂Si₂O₇ have the lowest thermal conductivity and suitable CTE, making them the best choices for advanced thermal/environmental barrier coatings in high-temperature applications. Furthermore, the in-depth discussion in this study provides guidance for designing high-entropy rare earth disilicate materials with ideal CTE and thermal insulation properties.