(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7: A novel high-entropy ceramic with low thermal conductivity and sluggish grain growth rate

Zhao, Zifan; Xiang, Huimin; Dai, Fu‐Zhi; Peng, Zhijian; Zhou, Yanchun

doi:10.1016/j.jmst.2019.05.054

Cited by 282 publications

(78 citation statements)

References 32 publications

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“…1,2 Compared to conventional single phase ceramics, HECs process unique properties and potential applications in many elds due to their high-entropy, severe lattice-distortion, sluggish diffusion, and cocktail effects. 3 Heretofore, numerous HECs, including oxides, 1,4 carbides, [5][6][7][8] diborides, 3,9−11 and disilicides, [12][13][14] have been extensively investigated due to their high-melting point (> 3273 K), excellent chemical stability at high temperature, and high hardness. Among these HECs, high-entropy disilicides are considered as the most promising high-temperature candidate material in that their individual components possess high melting points, high-temperature mechanical property retention, and excellent oxidation resistance.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of High-Entropy Disilicide Nanopowders via Molten Salt-Assisted Magnesium Thermal Reduction

Liu

Ning

2020

Preprint

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In this work, (Nb 0.25 Ta 0.25 Ti 0.25 Hf 0.25 )Si 2 high-entropy disilicide nanopowders were successfully fabricated via molten salt-assisted magnesium thermal reduction for the first time. The results showed that the as-obtained nanopowders possessed a single hexagonal structure (TaSi 2 -type) and consisted of numerous nanopowders with an average particle size of 55 nm . These nanopowders exhibited highly compositional uniformity at microscale , but shown the aggregation of Ti element at nanoscale. In addition, a typical template formation mechanism was proposed and analyzed in detailed. This work would provide a new way to synthesis of high-entropy disilicise powders for potential high-temperature harsh environment applications.

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Section: Introductionmentioning

confidence: 99%

Fabrication of High-Entropy Disilicide Nanopowders via Molten Salt-Assisted Magnesium Thermal Reduction

Liu

Ning

2020

Preprint

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“…Here, we typically distinguish HECs and MECs based on high-or medium-entropy mixing on one of the cation sublattices (typically according to the one with the highest ideal mixing entropy). For HECs with two cation sublattices, high-entropy mixing can occur at one cation sublattice, e.g., in (La1/5Ce1/5Nd1/5Sm1/5Eu1/5)2Zr2O7 [14,34] and (Ba1/2Sr1/5)(Zr1/5Sn1/5Ti1/5Hf1/5Nb1/5)O3 [26], or on both cationic sublattices, e.g., in (Gd1/5La1/5Nd1/5Sm1/5Y1/5)(Co1/5Cr1/5Fe1/5Mn1/5Ni1/5)O3 [25] ( Fig. 2).…”

Section: Graphical Abstractmentioning

confidence: 99%

“…Other oxide systems of significant interests include those with the fluorite [13,23,75,76,84], spinel [29][30][31][32]96], pyrochlore [14,[33][34][35][36][37], and perovskite [24][25][26][27][28] structures.…”

Section: Graphical Abstractmentioning

confidence: 99%

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

2020

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High-entropy ceramics (HECs) have quickly gained attention since 2015. To date, nearly all work has focused on five-component, equimolar compositions. This perspective article briefly reviews different families of HECs and selected properties. Following a couple of our most recent studies, we propose a step forward to expand HECs to Compositionally Complex ceramics (CCCs) to include medium-entropy and non-equimolar compositions. Using defective fluorite and ordered pyrochlore oxides as two primary examples, we further consider the complexities of aliovalent cations and anion vacancies as well as ordered structures with two cation sublattices.Better thermally-insulating yet stiff CCCs have been found in non-equimolar compositions with optimal amounts of oxygen vacancies and in ordered pyrochlores with substantial size disorder.It is demonstrated that medium-entropy ceramics (MECs) can prevail over their high-entropy counterparts. The diversifying classes of CCCs provide even more possibilities than HECs to tailor the composition, defects, disorder/order, and, consequently, various properties.

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“…These materials exhibit many intriguing properties, such as higher hardness, sluggish grain growth rate, lower thermal conductivity, strong microwave absorption capability and better water-vapor resistance, etc [29,30,31,32,33,34]. More importantly, our previous work indicates that high-entropy ceramics usually possess better high-temperature phase stability than the single-component ceramics owing to the entropy stabilization effect of HECs [35,36], which may provide a new way to improve the phase stability of RE4Al2O9 at high temperatures, i.e., through forming high-entropy solid solutions.…”

Section: Introductionmentioning

confidence: 99%

High-entropy (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 with good high temperature stability, low thermal conductivity and anisotropic thermal expansivity

Xiang

Chen

Dai

et al. 2020

Preprint

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The critical requirements for the environmental barrier coating (EBC) materials of silicon-based ceramic matrix composites (CMCs) including good tolerance to harsh environments, thermal expansion match with the interlayer mullite, good high-temperature phase stability and low thermal conductivity. Cuspidine-structured rare-earth aluminates RE4Al2O9 have been considered as candidates of EBCs for their superior mechanical and thermal properties, but the phase transition at high temperatures is a notable drawback of these materials. To suppress the phase transition and improve the phase stability, a novel cuspidine-structured rare-earth aluminate solid solution (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 was designed and successfully synthesized inspired by entropy stabilization effect of high entropy ceramics. The as-synthesized (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 exhibits close thermal expansion coefficient (6.96×10-6 /K at 300-1473 K) to that of mullite, good phase stability from 300 K to 1473 K, and low thermal conductivity (1.50 W·m-1·K-1 at room temperature). In addition, strong anisotropic thermal expansion has been observed compared to Y4Al2O9 and Yb4Al2O9. The mechanism for low thermal conductivity is attributed to the lattice distortion and mass difference of the constituent atoms while the anisotropic thermal expansion is due to the anisotropic chemical bonding enhanced by the large size rare earth cations.

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(La0.2Ce0.2Nd0.2Sm0.2Eu0.2)2Zr2O7: A novel high-entropy ceramic with low thermal conductivity and sluggish grain growth rate

Cited by 282 publications

References 32 publications

Fabrication of High-Entropy Disilicide Nanopowders via Molten Salt-Assisted Magnesium Thermal Reduction

Fabrication of High-Entropy Disilicide Nanopowders via Molten Salt-Assisted Magnesium Thermal Reduction

A step forward from high-entropy ceramics to compositionally complex ceramics: a new perspective

High-entropy (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 with good high temperature stability, low thermal conductivity and anisotropic thermal expansivity

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