J. Mater. Sci. Technol. ›› 2020, Vol. 48: 57-62.DOI: 10.1016/j.jmst.2020.01.056

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High entropy (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12: A novel high temperature stable thermal barrier material

Heng Chena,b, Zifan Zhaoa, Huimin Xianga, Fu-Zhi Daia, Wei Xuc, Kuang Sunc, Jiachen Liua, Yanchun Zhoua,*()   

  1. a Science and Technology on Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology, Beijing, 100076, China
    b Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin, 300072, China
    c Shanghai Chenhua Science and TechnologyCorporation Limted, Shanghai, 201804, China
  • Received:2019-11-22 Accepted:2019-12-19 Published:2020-07-01 Online:2020-07-13
  • Contact: Yanchun Zhou


Ytterbium aluminum garnet (Yb3Al5O12) is considered as a promising thermal barrier material. However, the main limitations of Yb3Al5O12 for thermal barrier applications are relative low thermal expansion coefficient and high thermal conductivity. In order to overcome these obstacles, herein, a new high entropy (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 ceramic was designed, and then powders and bulk were prepared through solid-state reaction method and spark plasma sintering (SPS), respectively. The thermal expansion coefficient of HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 is (8.54 ± 0.29) × 10-6 K-1 at 673 K-1273 K, which is about 9% higher than that of Yb3Al5O12. The thermal conductivity of HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 ceramic is 3.81 W·m-1 K-1 at 300 K, which is about 18 % lower than that of Yb3Al5O12. Moreover, there is no reaction between HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 and thermally grown (TG) Al2O3 even at 1600 °C. After annealing at 1590 °C for 18 h, the average grain size of HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 increases only from 1.56 μm to 2.27 μm. Close thermal expansion coefficient to TG Al2O3, low thermal conductivity, good phase stability, excellent chemical compatibility with TG Al2O3 and slow grain growth rate make HE (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 promising for thermal barrier applications.

Key words: High entropy ceramics, (Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12, Thermal barrier coatings, Thermal conductivity, Garnet