Composition effects on elastic, thermal and corrosion properties of multiple-RE silicate (Ho1/4Er1/4Yb1/4Lu1/4)2SiO5 as a promising thermal and environmental barrier coating material

(Ho1/4Er1/4Yb1/4Lu1/4)2SiO5 is synthesized and characterized for the application of a promising multifunctional thermal and environmental barrier coating (TEBC) material. X-ray diffraction and scanning electron microscopy analysis indicate that a X2-type multiple-RE silicate (4RE1/4)2SiO5 is formed with homogeneous distribution of the four rare earth species. Dense bulk sample exhibits excellent phase stability up to 1400 °C. Key properties including Young's modulus, thermal conductivity and thermal expansion coefficient show interesting composition effects. Specially, (Ho1/4Er1/4Yb1/4Lu1/4)2SiO5 demonstrates higher elastic stiffness, lower thermal conductivity, lower thermal expansion coefficient and good resistances to molten CMAS and water vapor corrosions. These results confirm the strategy of multiple-RE engineering that may provide optimal property of advanced TEBCs.