A novel sintering resistant Sr(Eu0.2Ho0.2Er0.2Tm0.2Yb0.2)2O4 high-entropy ceramic with superior thermophysical properties for advanced thermal barrier coatings

Recently SrY 2 O 4 noteworthy the scientific attention because of its excellent high-temperature structural stability and high thermal expansion coefficient. However, the high thermal conductivity and sintering acceleration limit the application of SrY 2 O 4 in the field of thermal barrier coatings. In this work, Sr(Eu 0.2 Ho 0.2 Er 0.2 Tm 0.2 Yb 0.2 ) 2 O 4 high-entropy ceramic that identified by computational screening was prepared by the solid-state method. The results show that Sr(Eu 0.2 Ho 0.2 Er 0.2 Tm 0.2 Yb 0.2 ) 2 O 4 has high thermal expansion coefficient (11.76×10 −6 K −1 , RT–1500 °C), low thermal conductivity (1.39 W·m −1 K −1 , 1500 °C), and improved fracture toughness (1.94 ± 0.05 MPa⋅m 1/2 ). Particularly, the average grain size increases only from 3.42 μm to 10.68 μm after heat treatment at 1600 °C for 10–100 h, indicating excellent sintering resistance. Density functional theory calculations within heterojunction models further reveals the intrinsic connection between the diffusion ability of the grain boundary atoms and the sintering resistance. This strategy provides new insight for the design of sintering-resistant thermal barrier coating materials.