Synthesis of superfine high-entropy metal diboride powders

Liu, Da; Wen, Tongqi; Ye, Beilin; Chu, Yanhui

doi:10.1016/j.scriptamat.2019.03.038

Cited by 152 publications

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“…That is to say, the synthesis of ZTNTC powders by one‐step carbothermal reduction is possible at enough high temperature with enough large driving force for the Reaction (). The similar results have also been well confirmed in the synthesis of high‐entropy diboride powders by one‐step borothermal reduction . Moreover, an empirical parameter (

δ

), which denotes the lattice size difference, has been proposed to predict the formation ability of some metal diboride or carbide solid solutions, which plays a positive role, and it can be expressed in ZTNTC by the following equation:

δ = \sqrt{\sum_{i = 1}^{n} c_{i} {()(, 1 - \frac{r_{i}}{\overset{false¯}{r}})}^{2}}

where n is the metal carbide component species in ZTNTC, c i is the molar fraction of the i th component of the metal carbides, and r i stands for the lattice constants of the individual metal carbides and

\overset{false¯}{r} = {false\sum}_{i = 1}^{n} c_{i} r_{i}

.…”

Section: Resultsmentioning

confidence: 53%

One‐step synthesis of coral‐like high‐entropy metal carbide powders

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Liu

et al. 2019

J Am Ceram Soc

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The synthesis of high‐entropy metal carbide powders is critical for implementing their extensive applications. However, the one‐step synthesis of high‐entropy metal carbide powders is rarely studied. Herein, the synthesis possibility of high‐entropy metal carbide powders, namely (Zr0.25Ta0.25Nb0.25Ti0.25)C (ZTNTC), via one‐step carbothermal reduction was first investigated theoretically by analyzing chemical thermodynamics and lattice size difference based on the first‐principle calculations, and then the ZTNTC powders with particle size of 0.5‐2 μm were successfully synthesized experimentally. The as‐synthesized powders not only had a single rock‐salt crystal structure of metal carbides, but also possessed high‐compositional uniformity from nanoscale to microscale. More interestingly, they exhibited the distinguished coral‐like morphology with the hexagonal step surface, whose growth was governed by a classical screw dislocation growth mechanism.

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δ

δ = \sqrt{\sum_{i = 1}^{n} c_{i} {()(, 1 - \frac{r_{i}}{\overset{false¯}{r}})}^{2}}

\overset{false¯}{r} = {false\sum}_{i = 1}^{n} c_{i} r_{i}

.…”

Section: Resultsmentioning

confidence: 53%

One‐step synthesis of coral‐like high‐entropy metal carbide powders

Ning

Liu

et al. 2019

J Am Ceram Soc

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“…[1][2][3][4][5][6] HEMs are based on the premise of incorporatingm ultiple components (usually five or more) into as ingle crystal phase to attain unique combination of properties that are otherwise unattainable in conventional solid solutions. The highentropyp erovskite oxidesw ere synthesized as monodispersed, spherical nanoparticles with an average crystallite sizeo fa pproximately 5.9 nm.…”

mentioning

confidence: 99%

“…The highentropyp erovskite oxidesw ere synthesized as monodispersed, spherical nanoparticles with an average crystallite sizeo fa pproximately 5.9 nm. Examples include high-entropy metal dibor-ides, [4] high-entropy nitrides, [8,9] and high-entropy metal oxides (HEMOs). Notably, the entropically-driven stability of Ru/BaSrBi(ZrHfTiFe)O 3 with excellent dispersion of Ru in the perovskite phase bestowed the nanoparticles of Ru/BaSrBi(ZrHfTiFe)O 3 with good catalytic activity for CO oxidation.…”

mentioning

confidence: 99%

“…[1][2][3][4][5][6] HEMs are based on the premise of incorporatingm ultiple components (usually five or more) into as ingle crystal phase to attain unique combination of properties that are otherwise unattainable in conventional solid solutions. [1][2][3][4][5][6] HEMs are based on the premise of incorporatingm ultiple components (usually five or more) into as ingle crystal phase to attain unique combination of properties that are otherwise unattainable in conventional solid solutions.…”

mentioning

confidence: 99%

“…[1][2][3][4][5][6] HEMs are based on the premise of incorporatingm ultiple components (usually five or more) into as ingle crystal phase to attain unique combination of properties that are otherwise unattainable in conventional solid solutions. Examples include high-entropy metal dibor-ides, [4] high-entropy nitrides, [8,9] and high-entropy metal oxides (HEMOs). Examples include high-entropy metal dibor-ides, [4] high-entropy nitrides, [8,9] and high-entropy metal oxides (HEMOs).…”

mentioning

confidence: 99%

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Room‐Temperature Synthesis of High‐Entropy Perovskite Oxide Nanoparticle Catalysts through Ultrasonication‐Based Method

et al. 2019

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In the present study,asonochemical-based method for onepot synthesis of entropy-stabilized perovskite oxide nanoparticle catalysts with high surface area was developed. The highentropyp erovskite oxidesw ere synthesized as monodispersed, spherical nanoparticles with an average crystallite sizeo fa pproximately 5.9 nm. Ta king advantage of the acoustic cavitation phenomenon in theu ltrasonication process, BaSr(ZrHf-Ti)O 3 ,B aSrBi(ZrHfTiFe)O 3 and Ru/BaSrBi(ZrHfTiFe)O 3 nanoparticles were crystallized as single-phase perovskite structures through ultrasonication exposure withoutc alcination. Notably, the entropically-driven stability of Ru/BaSrBi(ZrHfTiFe)O 3 with excellent dispersion of Ru in the perovskite phase bestowed the nanoparticles of Ru/BaSrBi(ZrHfTiFe)O 3 with good catalytic activity for CO oxidation.As ignificant breakthrough in multicomponent alloy systems has inspired the exploration of the vast compositional space offered by high-entropy materials (HEMs). [1][2][3][4][5][6] HEMs are based on the premise of incorporatingm ultiple components (usually five or more) into as ingle crystal phase to attain unique combination of properties that are otherwise unattainable in conventional solid solutions. [7] Amongt his novel class of crystalline materials, high-entropy alloys were first reported in 2004 by the independentp ioneering works of Cantor et al. and Yeh et al. [5,6] Recent studies have extended the high-entropy concept to include the ionic compounds, in which five or more metallice lements have been used to populate as inglec ation sublattice to introduce highc onfigurational entropyi nto the crystal structure. Examples include high-entropy metal dibor-ides, [4] high-entropy nitrides, [8,9] and high-entropy metal oxides (HEMOs). [10] More recently,J iang et al. extended the HEMO study to include perovskite-type oxides with six and seven metallice lements. [11] The synthesis involved blending and ball millingo fs toichiometric amounts of the corresponding metaloxide precursors for approximately 6h and subsequentc alcination at temperatures above 1300 8Ct of orm the high-entropy perovskite oxide (HEPO) ceramics. Although the particle size distribution of the synthesized perovskites was not reported, several studies have demonstrated that such extreme temperatured uring the synthetic process causes coagulation of grain boundaries, leadingt ot he formation of clumps, and consequent reduction in the available surfacea rea for reactions. [10,12,13] Although conventional perovskites with high-surface area have been synthesized previously, [14,15] high-entropy perovskites with high surfacearea have not been reported previously to the best of our knowledge.Perovskites are an important class of materials that exhibit a wide range of functionality,m aking them desirable for use in different areas of application including heterogenous catalysis. [16] In 1975, Gallagher et al. reported the use of perovskites as potentialr eplacement for noble-metal-based catalystsi na utomotive exhaust systems. [17] The initia...

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Synthesis and Processing of High‐Entropy Materials

2023

High‐Entropy Materials

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Synthesis of superfine high-entropy metal diboride powders

Cited by 152 publications

References 27 publications

One‐step synthesis of coral‐like high‐entropy metal carbide powders

One‐step synthesis of coral‐like high‐entropy metal carbide powders

Room‐Temperature Synthesis of High‐Entropy Perovskite Oxide Nanoparticle Catalysts through Ultrasonication‐Based Method

Synthesis and Processing of High‐Entropy Materials

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