Thermal performance regulation of high‐entropy rare‐earth disilicate for thermal environmental barrier coating materials

Abstract We prepared the novel high‐entropy ( x RE 1/ x ) 2 Si 2 O 7 (RE = Y, Yb, Er, Sc, Gd and Eu, x = 2–6) ceramics by a two‐step method for the application of thermal environmental barrier coatings (TEBCs), and the effect of configuration entropy and lattice distortion on microstructures and thermal properties at high temperature were investigated. The results showed that the configuration entropy resulted from mass disorder can only contribute to the stability of thermal properties and microstructure. Lattice distortion should be responsible for reduction in thermal properties, which may be due to the enhancement of atomic nonharmonic vibration, resulting in intensified phonon scattering and hindering atomic amplitude oscillation. As‐prepared high‐entropy (Y 1/6 Yb 1/6 Er 1/6 Sc 1/6 Gd 1/6 Eu 1/6 ) 2 Si 2 O 7 ceramic exhibited the relatively low thermal diffusivity, thermal conductivity and coefficient of thermal expansion, which were 0.89–0.50 mm 2 s –1 , 1.99–2.50 W m –1 K –1 and (3.01–3.78) × 10 –6 K –1 in the temperature range of 293–1373 K, respectively. This work provides a solid guarantee for the application of TEBC materials.