Abstract
Rare-earth tantalates and niobates (RE3TaO7 and RE3NbO7) have been considered as promising candidate thermal barrier coating (TBC) materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia (YSZ). However, the low Vickers hardness and toughness are the main shortcomings of RE3TaO7 and RE3NbO7 that limit their applications as TBC materials. To increase the hardness, high entropy (Y1/3Yb1/3Er1/3)3TaO7, (Y1/3Yb1/3Er1/3)3NbO7, and (Sm1/6Eu1/6Y1/6Yb1/6Lu1/6Er1/6)3(Nb1/2Ta1/2)O7 are designed and synthesized in this study. These high entropy ceramics exhibit high Vickers hardness (10.9–12.0 GPa), close thermal expansion coefficients to that of single-principal-component RE3TaO7 and RE3NbO7 (7.9×10−6-10.8×10−6C−1 at room temperature), good phase stability, and good chemical compatibility with thermally grown Al2O3, which make them promising for applications as candidate TBC materials.
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Acknowledgements
This study was financially supported by the National Natural Science Foundation of China (Nos. 51672064 and 51972089).
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Zhao, Z., Chen, H., Xiang, H. et al. High entropy defective fluorite structured rare-earth niobates and tantalates for thermal barrier applications. J Adv Ceram 9, 303–311 (2020). https://doi.org/10.1007/s40145-020-0368-7
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DOI: https://doi.org/10.1007/s40145-020-0368-7