In:
Journal of the American Ceramic Society, Wiley, Vol. 105, No. 8 ( 2022-08), p. 5490-5500
Abstract:
Pursuing novel thermal barrier–coating materials with lower thermal conductivity and high‐temperature stability can simultaneously improve the working efficiency and service temperature of a gas turbine. In this study, a series of high‐entropy RE 2 (Y 0.2 Yb 0.2 Nb 0.2 Ta 0.2 Ce 0.2 ) 2 O 7 (RE = La, Nd, Sm, Gd, Dy, and Er) oxides were prepared though solid‐state reaction. Through tuning the rare‐earth cations, an order–disorder transition occurs from certain partially ordered weberite structure ( C 222 1 ) to disordered defective fluorite structure ( Fm m ). All the high‐entropy RE 2 (Y 0.2 Yb 0.2 Nb 0.2 Ta 0.2 Ce 0.2 ) 2 O 7 oxides possess low thermal conductivity in the range of 0.91–1.34 W m −1 K −1 at room temperature, which can be attributed to increased lattice anharmonicity and disorder, resulting in additional phonon scattering. Herein, we proved that the incorporation of heterovalent cations at B‐sites in high‐entropy A 2 B 2 O 7 crystals is an effective strategy to reduce the thermal conductivity without compromising the decrease of oxygen vacancy. Moreover, the high‐entropy RE 2 (Y 0.2 Yb 0.2 Nb 0.2 Ta 0.2 Ce 0.2 ) 2 O 7 oxides show the relatively higher thermal expansion coefficients of 10.3–10.7 × 10 −6 °C −1 and excellent phase stability at elevated temperatures.
Type of Medium:
Online Resource
ISSN:
0002-7820
,
1551-2916
Language:
English
Publisher:
Wiley
Publication Date:
2022
detail.hit.zdb_id:
2008170-4
detail.hit.zdb_id:
219232-9
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