A Promising High-Entropy Thermal Barrier Material with the Formula (Y0.2Dy0.2Ho0.2Er0.2Yb0.2)3Al5O12

Zhanqiang Li; Junfeng Zheng; Wenjuan Zhang; Yong Zheng; Weijun Zhao; Liyan Xue; Fan Yang; Heng Chen

doi:10.3390/ma15228079

A Promising High-Entropy Thermal Barrier Material with the Formula (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂

Materials (Basel). 2022 Nov 15;15(22):8079. doi: 10.3390/ma15228079.

Authors

Zhanqiang Li^{1

2

3}, Junfeng Zheng³, Wenjuan Zhang³, Yong Zheng⁴, Weijun Zhao³, Liyan Xue^{1

3

5

6}, Fan Yang^{1

2

5

6

7}, Heng Chen^{3

5

6

7}

Affiliations

¹ Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
² University of Chinese Academy of Sciences, Beijing 100049, China.
³ Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institute, Chinese Academy of Sciences, Xiamen 361021, China.
⁴ Nuclear Power Institute of China, The Key Nuclear Fuel and Nuclear Materials Laboratory of China, Chengdu 610213, China.
⁵ Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou 350108, China.
⁶ Fujian Province Joint Innovation Key Laboratory of Fuel and Materials in Clean Nuclear Energy System, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.
⁷ Advanced Energy Science and Technology Guangdong Laboratory, Huizhou 516003, China.

Abstract

YSZ has been widely used as a TBC material, but its phase change at high temperatures limits its development, thus the need for developing new thermal barrier materials resistant to high temperatures. Rare-earth aluminate ceramics with a garnet structure (Yb₃Al₅O₁₂) have been considered as a potential thermal barrier material. The melting point of Yb₃Al₅O₁₂ is 2000 °C, which has a potential high temperature application prospect. However, Yb₃Al₅O₁₂ has lower thermal expansion and higher thermal conductivity than YSZ, which is a widely employed thermal barrier coating (TBC) material. To overcome these obstacles, (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂, a high-entropy ceramic, was prepared by a solid-state reaction and pressureless sintering. The thermal conductivity of the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ was 3.48 W/(m·K) at 300 K, approximately 25.48% lower than that of the Yb3Al5O12 (4.67 W/(m·K)). The thermal expansion coefficient of the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ was 9.28 × 10^-6 K^-1 at 673-1273 K, approximately 18.52% higher than that of the Yb₃Al₅O₁₂ (7.83 × 10^-6 K^-1, 673-1273 K). When the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ was annealed at 1550 °C for 7 days, its average grain size only increased from 0.7 μm to 1.3 μm. Moreover, the (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ exhibited better chemical stability and a lower grain growth rate than the Yb₃Al₅O₁₂. This study reveals that (Y_0.2Dy_0.2Ho_0.2Er_0.2Yb_0.2)₃Al₅O₁₂ is a promising candidate for the future generation of thermal barrier materials.

Keywords: chemical stability; high-entropy ceramics; rare-earth aluminates; thermal barrier material.

Abstract

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