Ultra-low thermal conductivity and enhanced mechanical properties of high-entropy rare earth niobates (RE3NbO7, RE = Dy, Y, Ho, Er, Yb)

Zhu, Jiatong; Meng, Xuanyu; Xu, Jie; Zhang, Ping; Lou, Zhihao; Reece, Michael J.; Gao, Feng

doi:10.1016/j.jeurceramsoc.2020.08.070

Cited by 102 publications

(24 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…9,10 High-entropy ceramics, in which four or more components with equimolar or near equimolar amounts populate the same lattice sites, is beneficial to reducing thermal conductivity due to the significant lattice distortions and high defect concentrations compared with the corresponding single-component ceramics. [11][12][13][14][15][16][17] In recent years, several kinds of high-entropy A 2 B 2 O 7type oxides with multiple A-site rare-earth (RE) cations are designed and synthesized successfully. 6,[18][19][20][21][22][23] Their thermal conductivities are below 2.2 W⋅m −1 ⋅K −1 and are varied with the selection of A-site RE cations and relative densities.…”

Section: Introductionmentioning

confidence: 99%

“…It has been proved that the formation of lattice point defects such as vacancies and element substitutions is an effective approach to enhance the phonon‐defect scattering and decrease thermal conductivity with the increasing defect concentration 9,10 . High‐entropy ceramics, in which four or more components with equimolar or near equimolar amounts populate the same lattice sites, is beneficial to reducing thermal conductivity due to the significant lattice distortions and high defect concentrations compared with the corresponding single‐component ceramics 11–17 …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

High‐entropy yttrium pyrochlore ceramics with glass‐like thermal conductivity for thermal barrier coating application

et al. 2022

View full text Add to dashboard Cite

A 2 B 2 O 7 -type oxides with low thermal conductivities are potential candidates for next-generation thermal barrier coatings. The formation of high-entropy ceramics is considered as a newly effective way to further lower their thermal conductivities. High-entropy Y 2 (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2 ) 2 O 7 (5HEO) and Y 2 (Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 ) 2 O 7 (4HEO) ceramics were prepared by in situ solid reaction sintering, considering the important roles of B-site cations on thermal conductivities of the A 2 B 2 O 7 -type oxides. Reaction process, phase structures, microstructures, and thermal conductivities of the as-sintered ceramics were investigated. Lattice distortion effects on their thermal conductivities were also discussed by using the proposed criterion based on the supercell volume difference of the individual compounds. Near fully-dense 5HEO and 4HEO ceramics were obtained after being sintered at 1600 • C. The former one had a dual-phase structure containing high-entropy Y 2 (Ti 0.227 Zr 0.227 Hf 0.227 Nb 0.136 Ta 0.182 ) 2 O 7.318 pyrochlore oxide (5HEO-P) and Y(Nb, Ta)O 4 solid solution, while the latter one was a single-phase pyrochlore oxide (4HEO-P) with homogeneous element distribution. The formed 5HEO-P oxide has larger lattice distortion than 4HEO-P oxide due to the larger total amounts of Nb and Ta cations at B sites in the 5HEO-P oxide. It results in lower thermal conductivity of 5HEO ceramics (keeping at 1.8 W⋅m -1 ⋅K -1 ) than those of 4HEO ceramics (ranging from 1.8 to 2.5 W⋅m -1 ⋅K -1 ) at temperatures from 25 • C to 1400 • C. Their glass-like thermal conductivities were determined by the selection of B site cations and high-entropy effects. These results provide some useful information for the material design of novel thermal barrier coating materials.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High‐entropy yttrium pyrochlore ceramics with glass‐like thermal conductivity for thermal barrier coating application

et al. 2022

View full text Add to dashboard Cite

show abstract

“…10−13 For example, Zhu et al prepared novel entropy-stabilized RE 3 NbO 7 (RE = Dy, Y, Ho, Er, and Yb) oxides, and their results revealed that the prepared ceramics hold superior mechanical properties (K IC = 2.13 MPa m 1/2 and H v = 9.51 GPa) as well as a low thermal conductivity (the lowest thermal conductivity could reach 0.724 W m −1 K −1 at 25 °C) that results from the increased configuration entropy. 14 Wang and Reece fabricated an Hf−Ta−Zr−Nb−C entropy-stabilized carbide and found that the synthesized ceramics manifest a higher oxidation onset temperature (785 °C) than the four component monocarbides, i.e., HfC, TaC, NbC, and ZrC. It suggests a synergistic effect of the multicomponents on its oxidation behavior, which may be bound up with entropy stabilization.…”

Section: ■ Introductionmentioning

confidence: 99%

Enhanced Structural and Aging Stability in Cation-Disordered Spinel-Type Entropy-Stabilized Oxides for Thermistors

Wang

Yao

Wang

et al. 2022

ACS Appl. Electron. Mater.

View full text Add to dashboard Cite

Entropy-stabilized ceramics (ESCs) are an emerging group of solid solutions that contain five or more elemental species. These materials possess great compositional flexibility and are of vital technical and scientific significance in many applications, covering catalysis, lithium-ion batteries, thermal barrier coatings, super-ionic conductors, etc. Here, a novel class of (Co 0.2 Mn 0.2 Fe 0.2 Zn 0.2 Ni 0.2 ) 3 O 4 ESCs was designed and synthesized using the solid-state reaction technique for thermistor applications following the entropy-stabilized design strategy. Moreover, as a critical parameter in the formation of entropy stability, the influences of sintering temperature on structural and electrical behavior were systematically investigated at 1150−1225 °C. Our results indicate that each of the synthesized samples exhibits a single spinel structure in the space group Fd-3m (227), and all five species are uniformly distributed on the nanometer scale, indicating entropy stabilization. Also, the fabricated ESCs manifest excellent negative temperature coefficient (NTC) characteristics and outstanding aging stability (ΔR/R 0 = 0.19%). Such ESCs will be an attractive candidate material for thermistor applications and provide new insights into the further development of advanced electronic ceramics.

show abstract

“…Earlier researchers initially studied simple oxide compounds based on divalent metals (Mg, Co, Ni, Cu and Zn, for example, in [ 22 , 27 , 28 ]) or trivalent metals [ 30 , 31 ]. However, their interest was quickly attracted by HEO compounds with a more complex crystal structure than systems formed only by oxides of tri- or bi-valent metals [ 32 , 33 , 34 , 35 , 36 ]. Phases of high-entropy oxides with a spinel-like crystal structure were obtained in [ 37 , 38 ].…”

Section: Introductionmentioning

confidence: 99%

Polysubstituted High-Entropy [LaNd](Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 Perovskites: Correlation of the Electrical and Magnetic Properties

et al. 2021

View full text Add to dashboard Cite

La-, Nd- and La/Nd-based polysubstituted high-entropy oxides (HEOs) were produced by solid-state reactions. Composition of the B-site was fixed for all samples (Cr0.2Mn0.2Fe0.2Co0.2Ni0.2) with varying of A-site cation (La, Nd and La0.5Nd0.5). Nominal chemical composition of the HEOs correlates well with initial calculated stoichiometry. All produced samples are single phase with perovskite-like structure. Average particle size is critically dependent on chemical composition. Minimal average particle size (~400 nm) was observed for the La-based sample and maximal average particle size (5.8 μm) was observed for the Nd-based sample. The values of the configurational entropy of mixing for each sample were calculated. Electrical properties were investigated in the wide range of temperatures (150–450 K) and frequencies (10−1–107 Hz). Results are discussed in terms of the variable range hopping and the small polaron hopping mechanisms. Magnetic properties were analyzed from the temperature and field dependences of the specific magnetization. The frustrated state of the spin subsystem was observed, and it can be a result of the increasing entropy state. From the Zero-Field-Cooling and Field-Cooling regimes (ZFC-FC) curves, we determine the <S> average and Smax maximum size of a ferromagnetic nanocluster in a paramagnetic matrix. The <S> average size of a ferromagnetic cluster is ~100 nm (La-CMFCNO) and ~60 nm (LN-CMFCNO). The Smax maximum size is ~210 nm (La-CMFCNO) and ~205 nm (LN-CMFCNO). For Nd-CMFCNO, spin glass state (ferromagnetic cluster lower than 30 nm) was observed due to f-d exchange at low temperatures.

show abstract

Ultra-low thermal conductivity and enhanced mechanical properties of high-entropy rare earth niobates (RE3NbO7, RE = Dy, Y, Ho, Er, Yb)

Cited by 102 publications

References 32 publications

High‐entropy yttrium pyrochlore ceramics with glass‐like thermal conductivity for thermal barrier coating application

High‐entropy yttrium pyrochlore ceramics with glass‐like thermal conductivity for thermal barrier coating application

Enhanced Structural and Aging Stability in Cation-Disordered Spinel-Type Entropy-Stabilized Oxides for Thermistors

Polysubstituted High-Entropy [LaNd](Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 Perovskites: Correlation of the Electrical and Magnetic Properties

Contact Info

Product

Resources

About