Highly anti-sintering and toughened pyrochlore (Dy0.2Nd0.2Sm0.2Eu0.2Yb0.2)2Zr2O7 high-entropy ceramic for advanced thermal barrier coatings
Single-phase high-entropy rare-earth zirconate (Dy 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2 ) 2 Zr 2 O 7 with excellent high-temperature phase stability at 1600 °C was designed and synthesized. After being heated at 1600 °C for 1 ∼ 50 h, the average grain size of the sample increases only from 0.74 μm to 2.22 μm, indicating a high anti-sintering ability. The fracture toughness is 2.07 ± 0.03 MPa m 1/2 (25 °C), which is 50% higher than lanthanum zirconate. The local lattice distortions induced by the atomic interactions and atomic-size mismatch are considered to be responsible for the strong anti-sintering ability and improved fracture toughness. In addition, the thermal expansion coefficient and thermal conductivity of (Dy 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2 ) 2 Zr 2 O 7 are 10.59 × 10 -6 K -1 (25 ∼ 1500 °C) and 1.14 ± 0.09 W·m -1 ·K -1 (1500 °C), respectively. The outstanding combination of anti-sintering ability, mechanical behavior , and thermophysical properties of (Dy 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Yb 0.2 ) 2 Zr 2 O 7 highlights its great potential for next-generation thermal barrier coating applications.
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