Preparation of High-Entropy (Ti, Zr, Hf, Ta, Nb) Carbide Powder via Solution Chemistry

Šolcová, Pavlína; Nižňanský, Matěj; Schulz, Jiří; Brázda, Petr; Ecorchard, Petra; Vilémová, Monika; Tyrpekl, Václav

doi:10.1021/acs.inorgchem.1c00776

Cited by 13 publications

(5 citation statements)

References 12 publications

(24 reference statements)

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“…12,35,52−65 These HEMs are located near the bottom left of the ΔH r − ⟨|ΔE D |⟩ plot, distinctly separate from the compositions that were experimentally attempted but consistently resulted in multiphases, 35,[59][60][61][62]64,65 which are positioned close to the upper right corner of the plot. Notably, the predicted top four-metal carbide HfNbTiZrC 4 , 52 top five-metal carbide HfNbTa-TiZrC 5 , 66,67 and top six-metal carbide HfNbTaTiVZrC 6 63 have all been experimentally validated.…”

Section: ■ Resultsmentioning

confidence: 85%

“…Remarkably, all experimentally reported single-phase high-entropy metal carbides (marked as green circles), except for CrMoTiVWC 5 (marked as B2 compound in the figure), are predicted by MEED. ,,− These HEMs are located near the bottom left of the Δ H r – ⟨|Δ E D |⟩ plot, distinctly separate from the compositions that were experimentally attempted but consistently resulted in multiphases, ,− ,, which are positioned close to the upper right corner of the plot. Notably, the predicted top four-metal carbide HfNbTiZrC 4 , top five-metal carbide HfNbTaTiZrC 5 , , and top six-metal carbide HfNbTaTiVZrC 6 have all been experimentally validated.…”

Section: Resultsmentioning

confidence: 91%

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Mixed Enthalpy–Entropy Descriptor for the Rational Design of Synthesizable High-Entropy Materials Over Vast Chemical Spaces

Dey,

Liang,

2024

J. Am. Chem. Soc.

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The practically unlimited high-dimensional composition space of high-entropy materials (HEMs) has emerged as an exciting platform for functional material design and discovery. However, the identification of stable and synthesizable HEMs and robust design rules remains a daunting challenge. Here, we propose a mixed enthalpy−entropy descriptor (MEED) that enables highly efficient, robust, high-throughput prediction of synthesizable HEMs across vast chemical spaces from first-principles. The MEED is based on two parameters: the relative formation enthalpy with respect to the most stable competing compound and the spread of the point-defect formation energy spectrum. The former measures the relative synthesizability of an HEM to its most stable competing phase, going beyond the conventional thermodynamic understanding. The latter gauges the relative entropy forming ability of an HEM, entailing no sampling over numerous alloy configurations. By applying the MEED to two structurally distinct representative material systems (i.e., 3D rocksalt carbides and 2D layered sulfides), we not only successfully identify all experimentally reported HEMs within these systems but also reveal a cutoff criterion for assessing their relative synthesizability within each system. By the MEED, tens of new high-entropy carbides and 2D high-entropy sulfides are also predicted, which have the potential for a wide variety of applications such as coating in aerospace devices, energy conversion and storage, and flexible electronics.

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Section: ■ Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 91%

Mixed Enthalpy–Entropy Descriptor for the Rational Design of Synthesizable High-Entropy Materials Over Vast Chemical Spaces

Dey,

Liang,

2024

J. Am. Chem. Soc.

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“…When metallic Tc is formed in situ together with active carbon atoms, both components remain highly reactive and thus capable of forming Tc–C bonds. Note that the thermal decomposition of carbon-containing precursors has been successfully used for the synthesis of high-entropy (Ti, Zr, Hf, Ta, and Nb) carbide powders having great potential and wide application, or uranium carbide …”

Section: Resultsmentioning

confidence: 99%

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Kuznetsov,

German,

Nagovitsyna

et al. 2023

Inorg. Chem.

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Technetium–carbon nanophases are obtained by thermal decomposition of pertechnetates with large organic cations under an argon atmosphere. Parallel carbonization of organic cations (hexamethyleneiminium and triphenylguanidinium), which occurs during the thermal decomposition of their pertechnetates, leads to the formation of X-ray amorphous solid products. An X-ray absorption fine structure study revealed that they have a crystal structure containing technetium–carbon bonds with a length of 1.76 Å. After subsequent annealing treatment at 1073–1673 K, the synthesized technetium–carbon phase has a cubic lattice with an a of 4.01 ± 0.03 Å. The products of thermal decomposition of the same perrhenates are also X-ray amorphous; however, unlike that of pertechnetates, the distance between rhenium and carbon atoms in them is significantly greater (2.14 Å). After subsequent annealing, they have a hexagonal lattice. The electrochemical properties of technetium–carbon nanophases prepared by thermal decomposition of pertechnetates with large organic cations are different from the properties of those prepared with metallic technetium. The oxidation of technetium carbide to its oxides at the electrode surface observed in the first anodic scan of cyclic voltammograms can be used for the deposition of noble metal nanoclusters under open-circuit conditions to prepare composite catalysts for the hydrogen evolution reaction. Nanotechnetium in the amorphous carbon matrix can also be a prospective material for reactor transmutation of technetium to stable isotopically pure ruthenium-100.

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“…The polymer-derived ceramic (PDC) route was also applied to synthesise HEC powders [58][59][60][61]. A typical route is shown in Figure 3.…”

Section: Hec Powdersmentioning

confidence: 99%

Processing and properties of high entropy carbides

Wang

2021

Advances in Applied Ceramics

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High entropy carbides (HECs) are novel materials developed in recent years that have attracted a lot of research interests. Unlike traditional carbides (containing one or two metals), HECs with multiple metals could form a very large number of different compositions that could have interesting and promising properties. The high entropy effect stabilises multi-component carbide phases and forms compositions that might otherwise not be stable. After several years of investigation of HECs, several methods of synthesising HECs have been developed. The microstructures and properties of HECs have been studied and compared with traditional carbides. Many interesting discoveries in HECs have been made. This paper reviews the theories, technologies, findings and insights gained from previous studies on HECs. The basic theory of HECs, the prediction of synthesisability of HEC phases from theoretical calculations, and some rules observed from experimental results are summarised. The preparation methods of HECs (powders, coatings, films and ceramics) and their microstructures are reviewed. Their properties, including thermal and electrical, mechanical and tribological, and oxidation, irradiation, and corrosion resistance of HECs are reviewed and discussed. Compared with traditional carbides, there is a great potential to develop new HECs due to their designable and complex compositions, and this review can guide future studies.

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Preparation of High-Entropy (Ti, Zr, Hf, Ta, Nb) Carbide Powder via Solution Chemistry

Cited by 13 publications

References 12 publications

Mixed Enthalpy–Entropy Descriptor for the Rational Design of Synthesizable High-Entropy Materials Over Vast Chemical Spaces

Mixed Enthalpy–Entropy Descriptor for the Rational Design of Synthesizable High-Entropy Materials Over Vast Chemical Spaces

Route to Stabilization of Nanotechnetium in an Amorphous Carbon Matrix: Preparative Methods, XAFS Evidence, and Electrochemical Studies

Processing and properties of high entropy carbides

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