Facile Electrochemical Synthesis of Nanoscale (TiNbTaZrHf)C High‐Entropy Carbide Powder

Sure, Jagadeesh; Vishnu, D. Sri Maha; Kim, Hyun Kyung; Schwandt, Carsten

doi:10.1002/ange.202003530

Cited by 21 publications

(8 citation statements)

References 43 publications

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“…24 In addition, a feasible process was proposed to fabricate HEC powders with nanoscale particle size by molten salt electro-deoxidation. 25 As for molten medium method, the medium acted as the matrix or catalyst to facilitate the resetting, diffusion, and solid solution of elements. [26][27][28] A summary of the different approaches is listed in Table 1, and these three kinds of methods can achieve the homogenization of components at a temperature below 2000 K compared to others.…”

Section: Introductionmentioning

confidence: 99%

“…Mechanosynthesis process from the mixture of elements would induce metal alloying followed by carbon diffusion under long periods of high energy ball milling 24 . In addition, a feasible process was proposed to fabricate HEC powders with nanoscale particle size by molten salt electro‐deoxidation 25 . As for molten medium method, the medium acted as the matrix or catalyst to facilitate the resetting, diffusion, and solid solution of elements 26–28 .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of high entropy carbide powders by low temperature processing

Wang

Cui

et al. 2022

Int J Applied Ceramic Tech

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High-entropy carbides (HECs) possess superior properties such as favorable corrosion resistance and marvelous hardness and are widely applied in specific extreme environments. Herein, a novel method was proposed for synthesizing HECs powders with raw materials of corresponding oxides and carbon black, which was composed of steps of ball-milling in stainless jar, carbothermic reduction at 1873 K, as well as the following calcium posttreatment at 1273 K to remove residual carbon by generating CaC 2 . Finally, pure HECs powders could be fabricated after acid leaching treatment. Under the current experimental conditions, besides HfC-TaC-ZrC-NbC quaternary system, a homogeneous solid solution could be fabricated by adding Mo or/and Ti, but it could not be achieved for systems with addition of V, W, or Cr, owing to the low lattice constant or different crystal structure of corresponding carbides. In the reduction step, iron resulted from ball milling process acted as the diffusion channel to promote the mutual diffusion of different components. Meanwhile, the calcium treatment temperature had a weak effect on particle size of HEC powders. HfC-TaC-ZrC-NbC-MoC-TiC powders prepared at the calcium posttreatment temperature of 1273 K had an oxygen content of .302% and an average grain size of 252 nm.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis of high entropy carbide powders by low temperature processing

Wang

Cui

et al. 2022

Int J Applied Ceramic Tech

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“…14 Seminal work by the Hu group circumvented this challenge by utilizing rapid solid-state synthesis, termed carbothermal shock synthesis, which involved millisecond heating of metal precursor salt mixtures followed by rapid temperature quenching. 15 In recent years, a number of solid state synthesis methods for HEA materials made their debut such as electrosynthesis, 16,17 fast-moving bed pyrolysis, 18 laser ablation, 19,20 aerosol synthesis, 21 and microwave heating synthesis. 22 In general, these prior synthesis routes used high temperature and rapid temperature quenching to generate kinetically trapped HEA nanostructures.…”

Section: Introductionmentioning

confidence: 99%

Visualizing Formation of High Entropy Alloy Nanoparticles by Aggregation of Amorphous Metal Cluster Intermediates

Sun

Leff

et al. 2022

Preprint

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High entropy alloy (HEA) nanoparticles hold promise as active and durable (electro)catalysts. Understanding their formation mechanism will enable rational control over the atomic arrangement of multimetallic catalytic surface sites. While prior reports have attributed HEA nanoparticle formation to nucleation and growth, there is a dearth of detailed mechanistic investigations. Here we utilize transmission electron microscopy (TEM), systematic synthesis, and mass spectrometry (MS) to demonstrate that HEA nanoparticles form by aggregation of non-crystalline multimetallic cluster intermediates. AuAgCuPtPd HEA nanoparticles were synthesized by aqueous co-reduction of metal salts with sodium borohydride in the presence of thiolated polymer ligands. Varying the metal:ligand ratio during synthesis showed that alloyed HEA nanoparticles formed only above a threshold ligand concentration. Alloyed sub-nanometer clusters were observed with the final HEA nanoparticles while few clusters were observed when phase-separated nanoparticles formed. Increasing supersaturation ratio increased particle size, which together with the observations of stable single atoms smaller than the critical nuclei size was inconsistent with a burst nucleation mechanism. Direct real-time observations with liquid phase TEM imaging showed that HEA nanoparticles formed by aggregation of sub-nanometer clusters. Taken together, these results are consistent with a reaction mechanism involving rapid reduction of metal ions into sub-nanometer alloyed clusters, followed by cluster aggregation driven by borohydride ion induced thiol ligand desorption. This work suggests intermediate cluster species as potential synthetic handles for rational control over HEA nanoparticle atomic structure.

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“…Titanium can be obtained in one-step reduction process [ 13 , 14 ]. At present, the electrochemical method has already been intensely studied in preparation of alloys [ 15 , 16 , 17 , 18 , 19 ] and carbides [ 20 ].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium

Meng

Zhao

et al. 2022

Materials

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Electrochemical mechanisms of molten salt electrolysis from TiO2 to titanium were investigated by Potentiostatic electrolysis, cyclic voltammetry, and square wave voltammetry in NaCl-CaCl2 at 800 °C. The composition and morphology of the product obtained at different electrolysis times were characterized by XRD and SEM. CaTiO3 phase was found in the TiO2 electrochemical reduction process. Electrochemical reduction of TiO2 to titanium is a four-step reduction process, which can be summarized as TiO2→Ti4O7→Ti2O3→TiO→Ti. Spontaneous and electrochemical reactions take place simultaneously in the reduction process. The electrochemical reduction of TiO2→Ti4O7→Ti2O3→TiO affected by diffusion was irreversible.

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Facile Electrochemical Synthesis of Nanoscale (TiNbTaZrHf)C High‐Entropy Carbide Powder

Cited by 21 publications

References 43 publications

Synthesis of high entropy carbide powders by low temperature processing

Synthesis of high entropy carbide powders by low temperature processing

Visualizing Formation of High Entropy Alloy Nanoparticles by Aggregation of Amorphous Metal Cluster Intermediates

Electrochemical Mechanism of Molten Salt Electrolysis from TiO2 to Titanium

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