Electronic structure of cubic HfxTa1–xCy carbides from X-ray spectroscopy studies and cluster self-consistent calculations

Lavrentyev, A.A.; Gabrelian, B.V.; Vorzhev, Vladimir; Nikiforov, I. Ya.; Khyzhun, O.Y.; Rehr, J. J.

doi:10.1016/j.jallcom.2007.08.018

Cited by 29 publications

(11 citation statements)

References 28 publications

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“…Ta 0.8 Hf 0.2 C is arguably the highest melting point among known materials . Lavrentyev et al stated a strong hybridization of the Hf(Ta) 5 d ‐ and C 2 p ‐like states might be the reason for this high melting point . In addition, inspired by this high melting point, researchers started synthesizing TaC‐HfC composites or solid solutions (at least partially) by using hot pressing, pressure‐less sintering, and spark plasma sintering.…”

Section: Introductionmentioning

confidence: 99%

“…19 Lavrentyev et al stated a strong hybridization of the Hf(Ta) 5d-and C 2p-like states might be the reason for this high melting point. 20 In addition, inspired by this high melting point, researchers started synthesizing TaC-HfC composites or solid solutions (at least partially) by using hot pressing, pressure-less sintering, and spark plasma sintering. However, the compositions in these studies are limited by Ta 0.8 Hf 0.2 C and Ta x Hf 1Àx C. Very few studies have covered the full spectrum of HfC-TaC compositions.…”

Section: Introductionmentioning

confidence: 99%

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Solid solution synthesis of tantalum carbide‐hafnium carbide by spark plasma sintering

et al. 2017

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Solid solutions of Tantalum carbide (TaC) and Hafnium carbide (HfC) were synthesized by spark plasma sintering. Five different compositions (pure HfC, HfC‐20 vol% TaC, HfC‐ 50 vol% TaC, HfC‐ 80 vol% TaC, and pure TaC) were sintered at 1850°C, 60 MPa pressure and a holding time of 10 min without any sintering aids. Near‐full density was achieved for all samples, especially in the HfC‐contained samples. The porosity in pure TaC samples was caused by the oxygen contamination (Ta2O5) on the starting powder surface. The addition of HfC increased the overall densification by transferring the oxygen contamination from TaC surface and forming ultrafine HfO2 and Hf‐O‐C grains. With the increasing HfC concentration, the overall grain size was reduced by 50% from HfC‐ 80 vol% TaC to HfC‐20 vol% TaC sample. The solid solution formation required extra energy, which restricted the grain growth. The lattice parameters for the solid solution samples were obtained using X‐ray diffraction which had an excellent match with the theoretical values computed using Vegard's Law. The mechanical properties of the solid solution samples outperformed the pure TaC and HfC carbides samples due to the increased densification and smaller grain size.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Solid solution synthesis of tantalum carbide‐hafnium carbide by spark plasma sintering

et al. 2017

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“…Besides being refractory, tantalum carbide is of particular interest as an ultra‐high‐temperature ceramic (UHTC) and a material for composite UHTCs because of its thermo‐mechanical and thermo‐chemical stabilities. A significant number of researchers have reported recent results pertaining to the mechanical strength, fracture toughness, oxidation behavior, elastic properties, thermodynamic properties, hardness, ablative resistance, superconductivity, and electronic structure, 1–8 although research goes back much further.…”

Section: Introductionmentioning

confidence: 99%

Statistical Experimental Design Approach for the Solvothermal Synthesis of Nanostructured Tantalum Carbide Powders

Kelly

Graeve

2011

Journal of the American Ceramic Society

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We report on the preparation of tantalum carbide nanopowders via a modified solvothermal synthesis route by using experimental design principles. The reaction proceeds by self‐propagating behavior in a molten metal after thermal‐ignition of tantalum chloride, carbon, and a metal reductant. A 4 × 4 × 3 experimental design matrix was performed, without replication, to observe the effects of carbon stoichiometry, reductant stoichiometry, and reductant type on process response variables concerning phase purity, compound stoichiometry, crystallite size, particle size, and surface characteristics. Statistical verifications of the observed effects were performed using a 2 × 2 × 2 experimental design matrix with replication. Eleven conditions resulted in phase‐pure tantalum carbide, with an additional four nonoxide conditions with low secondary‐phase content. The stoichiometry (x in TaCx) ranged from 0.92 to 0.96, the average crystallite size ranged from 24 to 68 nm, the specific surface area ranged from 25 to 66 m2/g, and the average particle size ranged from 93 to 123 nm, indicating a low level of agglomeration.

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“…Among the UHTCs, tantalum carbide (TaC) and hafnium carbide (HfC) are of particular interest due to their extremely high melting points (~4000 K) which are the highest of any inorganic material. Recently, experimental and theoretical investigations have reported the excellent elastic and mechanical features of TaC and HfC, which determine their suitability as structural materials …”

Section: Introductionmentioning

confidence: 99%

Bond characteristics, mechanical properties, and high‐temperature thermal conductivity of (Hf_1−xTa_x)C composites

et al. 2019

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Bond characteristics, mechanical properties, and high‐temperature thermal conductivity of ultrahigh‐temperature ceramics (UHTCs), hafnium carbide (HfC), tantalum carbide (TaC), and their solid solution composites, were investigated using first‐principles calculations. Mulliken analyses revealed that Ta formed stronger covalent bonds with C than did Hf. Bond overlap analyses indicated that the Hf–C bond possessed mixed covalent and ionic bond characteristics, compared with the more covalent character of the Ta–C bond. Consequently, the overall elastic properties were enhanced with increasing number of Ta–C bonds in the composites. The overall metallicity of the composites also increased with increasing TaC content; thus, the mechanical properties did not improve monotonically. Our results indicate that adding a small amount of TaC to HfC or vice versa to produce a composite would create a new UHTC with greatly improved elastic and mechanical properties as well as high‐temperature thermal conductivity.

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Electronic structure of cubic HfxTa1–xCy carbides from X-ray spectroscopy studies and cluster self-consistent calculations

Cited by 29 publications

References 28 publications

Solid solution synthesis of tantalum carbide‐hafnium carbide by spark plasma sintering

Solid solution synthesis of tantalum carbide‐hafnium carbide by spark plasma sintering

Statistical Experimental Design Approach for the Solvothermal Synthesis of Nanostructured Tantalum Carbide Powders

Bond characteristics, mechanical properties, and high‐temperature thermal conductivity of (Hf_1−xTa_x)C composites

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Electronic structure of cubic HfxTa1–xCy carbides from X-ray spectroscopy studies and cluster self-consistent calculations

Cited by 29 publications

References 28 publications

Solid solution synthesis of tantalum carbide‐hafnium carbide by spark plasma sintering

Solid solution synthesis of tantalum carbide‐hafnium carbide by spark plasma sintering

Statistical Experimental Design Approach for the Solvothermal Synthesis of Nanostructured Tantalum Carbide Powders

Bond characteristics, mechanical properties, and high‐temperature thermal conductivity of (Hf1−xTax)C composites

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Bond characteristics, mechanical properties, and high‐temperature thermal conductivity of (Hf_1−xTa_x)C composites