Phase evolution, thermophysical and mechanical properties of high-entropy (Ce0.2Nd0.2Sm0.2Eu0.2Yb0.2)2Zr2O7 ceramic for advanced thermal barrier coatings
Xuewei Luo, Shuo Huang, Ruiqi Huang, Shuen Hou, Hongyun Jin
Abstract
Single-phase high-entropy rare-earth zirconate (Ce 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2 ) 2 Zr 2 O 7 with large thermal expansion coefficient (11.69 ×10 −6 K −1 , 25–1500 °C), low thermal conductivity (1.07 W m −1 K −1 , 1500 °C), and high fracture toughness (1.84 ± 0.03 MPa m 1/2 , 25 °C) was successfully synthesized using reverse coprecipitation and high-temperature calcination. The underlying mechanism governing the observed results was analyzed by considering the ionic bond strength, crystal lattice energy, and bond length. X-ray diffraction and Raman spectroscopy results demonstrated that the pyrochlore structured sample has excellent high-temperature phase stability. Moreover, after being heated at 1600 °C for 10–30 h, the average grain size of this sample only increases from 0.95 µm to 1.47 µm, indicating a sluggish grain growth rate. The outstanding combination of thermophysical and mechanical properties of the (Ce 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2 ) 2 Zr 2 O 7 emphasizes its enormous potential for next-generation thermal barrier coating applications.