From high-entropy ceramics to compositionally-complex ceramics: A case study of fluorite oxides

By Andrew J. Wright, Qingyang Wang, Chuying Huang, A. Nieto, Renkun Chen, Jian Luo. Journal of the European Ceramic Society, 2019

252 citations recorded by the source corpus.

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)xO2-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 (~210 GPa) and nanohardness (~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.

Subfields: Aerospace Engineering, Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/a02f73a54c1d97b0b616c4ab2e8b135ec9741c75

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Aerospace Engineering

1. Jian Luo
2. K. Edalati
3. P. Hopkins
4. Tyler J. Harrington
5. Andrew J. Wright
6. Kenneth S. Vecchio
7. Joshua Gild

In Materials Chemistry

1. Makoto Arita
2. K. Edalati
3. P. Hopkins
4. Jian Luo
5. Tatsumi Ishihara
6. Andrew J. Wright
7. Kenneth S. Vecchio

In Mechanical Engineering

1. Jian Luo
2. Andrew J. Wright
3. Joshua Gild
4. Tatsumi Ishihara
5. Makoto Arita
6. M. Fuji
7. K. Edalati
8. P. Hopkins

Citations in the corpus

• Dual-phase high-entropy ultra-high temperature ceramics (2020, background): “Most recently, Luo and co-workers propose to further broaden high-entropy ceramics to compositionally-complex ceramics or CCCs [17,32,33].”
• A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective (2020, background): “In one example of yttriastabilized zirconia (YSZ)-like defective fluorite oxides, non-equimolar medium-entropy compositions were found to exhibit further reduced thermal conductivity in comparison with their high-entropy equimolar counterparts, presumably due to the effects of oxygen vacancies clust”
• Defective high-entropy oxide photocatalyst with high activity for CO2 conversion (2021, methodology): “The presence of several cations in the HEO can also produce hybridized orbitals with higher activity for chemical reactions [16,17].”