期刊
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
卷 40, 期 54, 页码 2120-2129出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.jeurceramsoc.2020.01.015
关键词
High-Entropy ceramics (HECs); Compositionally-Complex ceramics (CCCs); Multi-Principal cation ceramics (MPCCs); Thermal conductivity; Thermal barrier coatings
资金
- U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy (EERE) under Solar Energy Technologies Office (SETO) [EE0008529]
- Vannevar Bush Faculty Fellowship (ONR) [N00014-16-1-2569]
- associated Laboratory-University Collaboration Initiative (LUCI) program
Using fluorite oxides as an example, this study broadens high-entropy ceramics (HECs) to compositionally-complex ceramics (CCCs) or multi-principal cation ceramics (MPCCs) to include medium-entropy and/or non-equimolar compositions. Nine compositions of compositionally-complex fluorite oxides (CCFOs) with the general formula of (Hf1/3Zr1/3Ce1/3)(1-x)(Y1/2X1/2)(x)O2-delta (X = Yb, Ca, and Gd; x = 0.4, 0.148, and 0.058) are fabricated. The phase stability, mechanical properties, and thermal conductivities are measured. Compared with yttria-stabilized zirconia, these CCFOs exhibit increased cubic phase stability and reduced thermal conductivity, while retaining high Young's modulus (similar to 210 GPa) and nanohardness (similar to 18 GPa). Moreover, the temperature-dependent thermal conductivity in the non-equimolar CCFOs shows an amorphous-like behavior. In comparison with their equimolar high-entropy counterparts, the medium-entropy non-equimolar CCFOs exhibit even lower thermal conductivity (k) while maintaining high modulus (E), thereby achieving higher E/k ratios. These results suggest a new direction to achieve thermally-insulative yet stiff CCCs (MPCCs) via exploring non-equimolar and/or medium-entropy compositions.
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