Electronic structure, Compton profiles and optical properties of TaC and TaN

Dashora, Alpa; Ahuja, B.L.

doi:10.1016/j.radphyschem.2010.06.009

Cited by 12 publications

(3 citation statements)

References 22 publications

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“…[16] TaC is a model UHTC from a fundamental perspective because of its exceptionally high melting temperature (%4000 K) due to the strong covalent bonding in this material. [17,18] The high melting temperature also creates processing challenges [19] and, thus, the preparation of high-purity and fully dense TaC is only a recent development. [20][21][22][23] In the field of ceramics, mechanical properties are very much controlled by extrinsic effects, especially porosity, that are responsible for the basic processing-microstructure-property paradigm of these materials.…”

Section: Introductionmentioning

confidence: 99%

Densification and Fracture Responses of (Ta_1−xW_x)C–WC Composites

et al. 2022

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The mechanical behavior of 90 vol% (Ta1−xWx)C–10 vol% WC (x ≈ 0.2) [90(Ta0.8W0.2)C–10WC] composites is described, achieving a significant enhancement in mean fracture strength compared with nominally pure TaC prepared under identical processing conditions (from 114 to 362 MPa), and a higher characteristic strength (from 188 to 377 MPa), while maintaining the same Weibull modulus of 13. The fracture strengths correspond to calculated critical flaw sizes in the range of 5–10 μm and are consistent with the microstructure observations presented. The 90(Ta0.8W0.2)C–10WC composite begins densification at an onset sintering temperature of 1503 K, which is 500 K lower than TaC. It also exhibits enhanced densification by inhibiting grain growth at sintering temperatures up to 2173 K, therefore resulting in a relative density of 98% compared with 80% for TaC. These results show a promising guideline from which ceramic additions can be chosen to enhance the densification and functionality of ultrahigh‐temperature ceramics.

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Section: Introductionmentioning

confidence: 99%

Densification and Fracture Responses of (Ta_1−xW_x)C–WC Composites

et al. 2022

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“…and Dashora et al [19]. We would like to extend our computational work on optical properties of Ta 2 C. To the best of our knowledge till to date there is no experimental or theoretical data available on the optical properties of Ta 2 C. In this paper, we also pay attention to revisit the existing theoretical data of TaC and Ta 2 C for various physical properties (e.g.…”

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confidence: 95%

“…Our study shows that the optical properties of both Ta 2 C and TaC compounds compliment the electronic structure calculations. Optical constants of Ta 2 C show significant dependence of the state of polarization of the incident electric field, and predict this material as optically anisotropic.and Dashora et al [19]. We would like to extend our computational work on optical properties of Ta 2 C. To the best of our knowledge till to date there is no experimental or theoretical data available on the optical properties of Ta 2 C. In this paper, we also pay attention to revisit the existing theoretical data of TaC and Ta 2 C for various physical properties (e.g.…”

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confidence: 97%

Comparison of structural, mechanical and optical properties of tantalum hemicarbide with tantalum monocarbide: ab initio calculations

et al. 2019

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First-principles calculations are employed to investigate and compare the structural, elastic and optical properties of tantalum hemicarbide Ta 2 C and tantalum monocarbide TaC. Calculated lattice constants of these carbides are in good agreement with available theoretical and experimental results. The mechanical stability of these carbides is affirmed by the estimated values of elastic constants. The estimated values of Vickers hardness indicate that TaC is harder than Ta 2 C. The values of Pugh's ratio and Poisson's ratio suggest the brittle nature of both Ta 2 C and TaC. The optical properties of Ta 2 C along two polarization directions [001] and [100] are studied in details for the first time. Our study shows that the optical properties of both Ta 2 C and TaC compounds compliment the electronic structure calculations. Optical constants of Ta 2 C show significant dependence of the state of polarization of the incident electric field, and predict this material as optically anisotropic.and Dashora et al [19]. We would like to extend our computational work on optical properties of Ta 2 C. To the best of our knowledge till to date there is no experimental or theoretical data available on the optical properties of Ta 2 C. In this paper, we also pay attention to revisit the existing theoretical data of TaC and Ta 2 C for various physical properties (e.g. structural, elastic, electronic etc). DFT [20,21] calculations are executed on tantalum carbides Ta 2 C and TaC by using the Cambridge Serial Total Energy Package (CASTEP) code [22]. Here the electron-ion interaction is considered by ultrasoft pseudopotentials for both Ta 2 C and TaC [23]. Perdew-Burke-Ernzerhof (PBE) form of generalized gradient approximation (GGA) is used to treat the exchange correlation energy [24]. Minimization of total energy is achieved by the technique proposed by Broyden, Fletcher, Goldfrab and Shanno [25]. The optimization of crystal structure is done with a plane wave cut off energy of 850 eV and 18×18×10 Monkhorst-Pack grid [26] for Ta 2 C. In case of TaC, plane wave cut off energy of 950 eV and 19×19×19 Monkhorst-Pack grid are used for optimization. Convergence threshold of 1×10 −5 eV atom −1 for the total energy, 0.03 eV Å −1 for the maximum force, 0.05 GPa for maximum stress, and 0.001 Å for maximum displacement are taken for all calculations. Computational procedure

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A Promising Application of Optical Hexagonal TaN in Photocatalytic Reactions

et al. 2018

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Searching for highly active and efficient photocatalysts for photo-induced/photo-assisted reactions remains the most challenging task for solar energy utilization. In previous studies,t he search for such materials has mainly focused on precious plasmonic metals (for example,A u, Ag, and Cu) and semiconductor oxides (for example,T iO 2 ,Z nO, and WO 3 ). Herein, we report the application of hexagonal tantalum mononitride (TaN) as an optical support in photocatalytic reactions,w hich could harness visible light to assist CO 2 conversion and decompose organic pollutants.T heoretical studies indicated that the improved electron-hole separation in polar TaNu nder visible-light illumination was critical for its use in photocatalysis.T his study could guide the use of TaNi nv arious photocatalytic reactions and wider optical applications.

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Electronic structure, Compton profiles and optical properties of TaC and TaN

Cited by 12 publications

References 22 publications

Densification and Fracture Responses of (Ta_1−xW_x)C–WC Composites

Densification and Fracture Responses of (Ta_1−xW_x)C–WC Composites

Comparison of structural, mechanical and optical properties of tantalum hemicarbide with tantalum monocarbide: ab initio calculations

A Promising Application of Optical Hexagonal TaN in Photocatalytic Reactions

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Electronic structure, Compton profiles and optical properties of TaC and TaN

Cited by 12 publications

References 22 publications

Densification and Fracture Responses of (Ta1−xWx)C–WC Composites

Densification and Fracture Responses of (Ta1−xWx)C–WC Composites

Comparison of structural, mechanical and optical properties of tantalum hemicarbide with tantalum monocarbide: ab initio calculations

A Promising Application of Optical Hexagonal TaN in Photocatalytic Reactions

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Densification and Fracture Responses of (Ta_1−xW_x)C–WC Composites

Densification and Fracture Responses of (Ta_1−xW_x)C–WC Composites