Multi-component strategy for remarkable suppression of thermal conductivity in strontium diyttrium oxide: The case of high-entropy Sr(Y0.2Sm0.2Gd0.2Dy0.2Yb0.2)2O4 ceramic

Anti-spinel oxide SrY 2 O 4 has attracted extensive attention as a promising host lattice due to its outstanding high-temperature structural stability and large thermal expansion coefficient (TEC). However, the overhigh thermal conductivity limits its application in the field of thermal barrier coatings . To address this issue, a novel high-entropy Sr(Y 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Yb 0.2 ) 2 O 4 ceramic was designed and synthesized for the first time via the solid-state method. It is found that the thermal conductivity of Sr(Y 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Yb 0.2 ) 2 O 4 is reduced to 1.61 W·m −1 ·K −1 , 53 % lower than that of SrY 2 O 4 (3.44 W·m −1 ·K −1 ) at 1500 °C. Furthermore, reasonable TEC (11.53 ×10 −6 K −1 , 25 °C ∼ 1500 °C), excellent phase stability, and improved fracture toughness (1.92 ± 0.04 MPa·m 1/2 ) remained for the high-entropy Sr(Y 0.2 Sm 0.2 Gd 0.2 Dy 0.2 Yb 0.2 ) 2 O 4 ceramic, making it a promising material for next-generation thermal barrier coatings.