New entropy-stabilized oxide with pyrochlore structure: Dy2(Ti0.2Zr0.2Hf0.2Ge0.2Sn0.2)2O7

Vayer, Florianne; Decorse, Claudia; Bérardan, David; Dragoe, Nita

doi:10.1016/j.jallcom.2021.160773

Cited by 27 publications

(20 citation statements)

References 35 publications

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“…The high-entropy oxide (HEO) concept is originated from the alloy system [11][12][13], and further widened by the successful fabrication of the binary oxide (Mg 0.2 Zn 0.2 Cu 0.2 Co 0.2 Ni 0.2 )O in 2015 by Rost et al [14]. Since then, the high-entropy oxides with different crystal structure including rock salt [15], fluorite [16], pyrochlore [17], perovskite [18], and spinel [19] have been paid attention. For example, fluoritetype (Ce 0.2 Zr 0.2 Hf 0.2 Sn 0.2 Ti 0.2 )O 2 ceramic was fabricated by Chen et al [16]; spinel-type (Co,Cr,Fe,Mn,Ni) 3 O 4 oxide was first successfully synthesized by Stygar et al and the corresponding phase/microstructure was further characterized [19].…”

Section: Introduction mentioning

confidence: 99%

Pyrochlore-based high-entropy ceramics for capacitive energy storage

Chen

Qi²,

Zhang³

et al. 2022

J Adv Ceram

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High-performance dielectrics are widely used in high-power systems, electric vehicles, and aerospace, as key materials for capacitor devices. Such application scenarios under these extreme conditions require ultra-high stability and reliability of the dielectrics. Herein, a novel pyrochlore component with high-entropy design of Bi1.5Zn0.75Mg0.25Nb0.75Ta0.75O7 (BZMNT) bulk endows an excellent energy storage performance of Wrec ≈ 2.72 J/cm3 together with an ultra-high energy efficiency of 91% at a significant enhanced electric field Eb of 650 kV/cm. Meanwhile, the temperature coefficient (TCC) of BZMNT (∼−220 ppm/°C) is also found to be greatly improved compared with that of the pure Bi1.5ZnNb1.5O7 (BZN) (∼−300 ppm/°C), demonstrating its potential application in temperature-reliable conditions. The high-entropy design results in lattice distortion that contributes to the polarization, while the retardation effect results in a reduction of grain size to submicron scale which enhances the Eb. The high-entropy design provides a new strategy for improving the high energy storage performance of ceramic materials.

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Section: Introduction mentioning

confidence: 99%

Pyrochlore-based high-entropy ceramics for capacitive energy storage

Chen

Qi²,

Zhang³

et al. 2022

J Adv Ceram

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“…This composition was confirmed by the corresponding EDS spectrum. Similarly to Dy 2 (TiZrHfGeSn) 2 O 7 , 8 this phase was not observed in the XRD pattern recorded after the annealing treatment, which could possibly be explained by a poor crystallization or an insufficient fraction. The existence of an amorphous or poorly crystallized phase containing Ge and Dy seems a reasonable hypothesis, as Ge is a well‐known glass network former.…”

Section: Resultsmentioning

confidence: 87%

“…Some compounds derived from this seminal composition present interesting physical properties, such as colossal dielectric constants, 3 high ionic conductivities, 4 or a surprising antiferromagnetic order observed despite the chemical disorder 5,6 . Even though a very large number of high‐entropy materials have been reported over the last years with various crystal structures and compositions, only a limited number of entropy‐stabilized oxides are known, with, for example, the rocksalt (MgCoNiCuZn)O, 2 the fluorite (TiZrHfCeSn)O 2 , 7 or the pyrochlore Dy 2 (TiZrHfGeSn) 2 O 7 8 …”

Section: Introductionmentioning

confidence: 99%

“…However, because the RE elements generally exhibit good solubility when mixed together, it is necessary to introduce the chemical disorder on the B site to obtain entropy‐stabilized pyrochlores. We already applied this approach recently to form Dy 2 (TiZrHfGeSn) 2 O 7 , leading to the first entropy‐stabilized pyrochlore 8 . To the best of our knowledge, since then the reported high‐entropy pyrochlores with chemical disorder introduced on the B site are RE 2 (TiZrHfSn) 2 O 7 (RE = Sm or Gd) 15,16 ; Y 2 (TiZrHfMoV) 2 O 7 , Y 2 (TiZrHfV) 2 O 7 , and Y 2 (TiZrHfMo) 2 O 7 17 ; RE 2 (ZrHfSnScNb) 2 O 7 and RE 2 (ZrHfSnScTa) 2 O 7 (RE = La or Nd) 18 ; and the two distorted pyrochlores Nd 2 (ZrHfSnScTa) 2 O 7 and Nd 2 (ZrHfSnTiNb) 2 O 7 19 .…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the chemical versatility in high‐entropy pyrochlores

et al. 2022

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This article reports on the exploration of the chemical versatility of entropy‐stabilized pyrochlores (A2B2O7) with large chemical disorder introduced on the B site, as well as the study of isovalent and aliovalent substitution on the B site and of Ca2+‐doping on the A site. Among all the 20 new compounds obtained in this study, 8 are entropy‐stabilized: RE2(TiZrHfGeSn)2 (with RE = Gd–Ho and Y), Pr2(TiZrHfScNb)2O7, and RE2(TiGeSnAlNb)2O7 (with RE = Er and Y). Moreover, some physical properties (magnetic, electrical, thermal, and optical properties) of these high‐entropy pyrochlores have been screened, and some of them could be potentially interesting for applications. For example, we observed low thermal diffusivity values (between 0.4 and 0.7 m2 s−1) making them interesting for thermal barrier coating or tunable optical bandgaps in the visible region that could make them appealing as photocatalysts or in optical applications. Furthermore, single‐phased compounds were obtained for almost all the rare earths (REs) on the A site. Therefore, when five nonmagnetic cations are used for the B site, it enables to study the magnetic properties and, more specifically, the influence of the local chemical and structural disorder on the exotic ground states observed in monocationic RE pyrochlores.

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“…In this kind of structure, the Zr atoms equally occupy the 16d site and RE atoms homogeneously occupy the 16c site. Specifically, the O atoms occupy the 8b and 48f sites, while the O vacancy occupies the 8a site [30,31]. Meanwhile, the defective fluorite structure (Fig.…”

Section: Phase Stability and Structural Characterizationmentioning

confidence: 99%

High-entropy Rare-earth Zirconate Ceramics With Low Thermal Conductivity for Advanced Thermal Barrier Coatings

Liu

Shi

et al. 2021

Preprint

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In this work, we have successfully fabricated a novel high-entropy rare-earth zirconate (La0.2Nd0.2Sm0.2Gd0.2Yb0.2)2Zr2O7 (5RE2Zr2O7) ceramics and its counterparts by using a new high-speed grinding strategy combined with typical solid-state reaction method. The X-ray diffraction (XRD) and Raman spectroscopy analysis indicated that the as-prepared 5RE2Zr2O7 ceramics performed single-phase defect fluorite-type structures with highly sintering resistant and excellent thermal stability. The possibility of formation of 5RE2Zr2O7 was verified via first-principles calculations. Meanwhile, the phase structure, thermophysical and mechanical properties of the samples were systematically investigated. The results showed that the 5RE2Zr2O7 ceramics demonstrated lower thermal conductivity (0.9-1.72 W·m-1·K-1) and higher thermal expansion coefficients (10.9 × 10-6 K-1 at 1273 K) than its counterparts. Furthermore, the 5RE2Zr2O7 ceramics presented outstanding mechanical properties including large Young’s modulus (186-257 GPa), higher fracture toughness and lower brittleness index than that of YSZ. Therefore, in view of various excellent properties, the as-prepared 5RE2Zr2O7 ceramics possess great potential for applications in the field of thermal barrier coatings.

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New entropy-stabilized oxide with pyrochlore structure: Dy2(Ti0.2Zr0.2Hf0.2Ge0.2Sn0.2)2O7

Cited by 27 publications

References 35 publications

Pyrochlore-based high-entropy ceramics for capacitive energy storage

Pyrochlore-based high-entropy ceramics for capacitive energy storage

Investigation of the chemical versatility in high‐entropy pyrochlores

High-entropy Rare-earth Zirconate Ceramics With Low Thermal Conductivity for Advanced Thermal Barrier Coatings

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