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6CCVD Research

Optical, Electronic Properties and Anisotropy in Mechanical Properties of “X” Type Carbon Allotropes

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2020-05-01
JournalMaterials
AuthorsJiao Cheng, Qidong Zhang
InstitutionsXi’an University of Architecture and Technology, Xidian University
Citations36
AnalysisFull AI Review Included

Executive Summary

Section titled “Executive Summary”

This study utilized first-principles calculations (DFT/HSE06) to systematically investigate the mechanical, electronic, and optical properties of seven X-type carbon allotropes, including Cubane-yne, TY Carbon, and Diamond.

  • Mechanical Stability: All seven investigated allotropes, which possess cubic symmetry, were confirmed to be mechanically stable based on Born criteria.
  • Anisotropy Quantification: The order of elastic anisotropy (Shear Modulus, Young’s Modulus, and Poisson’s Ratio) is quantified, with Cubane-yne exhibiting the largest anisotropy and Diamond the smallest.
  • Semiconductor Potential: TY Carbon, T Carbon, and Cubane-diyne are identified as promising semiconductor materials for photoelectric applications due to their high or comparable absorption coefficients relative to GaAs in the visible spectrum.
  • Electronic Structure: T Carbon (3.2 eV) and TY Carbon (2.2 eV) are predicted to be direct band gap semiconductors (HSE06 functional), contrasting with the indirect gaps found in Diamond (5.3 eV), Cubane-diyne, Cubane-yne, and Y Carbon.
  • Thermal Properties: Diamond possesses the highest Debye temperature (2224.84 K), indicating superior thermal stability and conductivity, while TY Carbon has the lowest (246.10 K).
  • Sound Velocity Anisotropy: TY Carbon exhibits the largest anisotropic ratio of sound velocity in the [110] propagation direction, while Cubane-diyne shows the smallest in the [100] direction.

Technical Specifications

Section titled “Technical Specifications”

Data extracted from Tables 1, 2, and 3, and text results (using HSE06 for band gaps where available).

ParameterValueUnitContext
Crystal SystemCubicN/AAll seven allotropes
Lattice Parameter (Diamond)3.566AngstromCalculated GGA value
Bulk Modulus (Diamond)431GPaHighest modulus
Young’s Modulus (Diamond)1116GPaHighest modulus
Shear Modulus (Cubane-diyne)22.5GPaLowest shear modulus
Emax/Emin Ratio (Cubane-yne)2.94RatioMaximum Young’s Modulus Anisotropy
Gmax/Gmin Ratio (Cubane-yne)10.44RatioMaximum Shear Modulus Anisotropy
Poisson’s Ratio Anisotropy (Cubane-yne)1.35RatioMaximum Poisson’s Ratio Anisotropy (Umax)
Debye Temperature (Diamond)2224.84KHighest thermal stability
Debye Temperature (TY Carbon)246.10KLowest thermal stability
Band Gap (Diamond)5.3eVHSE06, Indirect
Band Gap (TY Carbon)2.2eVHSE06, Direct
Band Gap (T Carbon)3.2eVHSE06, Direct
Static Dielectric Constant (Supercubane)5.118N/AHighest calculated value
Static Refractive Index (Supercubane)2.3N/AHighest calculated value n(0)

Key Methodologies

Section titled “Key Methodologies”

The study employed Density Functional Theory (DFT) for structural optimization and property prediction, utilizing the Cambridge Sequential Total Energy Package (CASTEP).

  1. DFT Implementation: Calculations were performed using the CASTEP software package.
  2. Pseudopotentials: Vanderbilt ultrasoft pseudopotentials were used.
  3. Exchange-Correlation Functional: The Perdew-Burke-Ernzerhof (PBE) functional within the Generalized Gradient Approximation (GGA) was primarily used for structural and mechanical properties.
  4. Electronic Structure Calculation: Electronic band structures and band gaps were calculated using both the PBE functional and the HSE06 hybrid functional (Heyd-Scuseria-Ernzerhof), with a mixing parameter (ε) of 0.25 and a screening parameter (ω) of 0.207 A-1.
  5. Energy Cutoff: A plane-wave energy cutoff (Ecutoff) of 520 eV was adopted for all allotropes.
  6. K-point Sampling: A high k-point separation of approximately 0.025 A-1 x 2π was used, with specific grids ranging from 4x4x4 up to 12x12x12 for the conventional cells.
  7. Structural Optimization Scheme: The Broyden-Fletcher-Goldfarb-Shanno (BFGS) minimization scheme was used for geometric optimization.
  8. Convergence Criteria: Strict convergence was enforced:
    • Maximum ionic displacement: < 5 x 10-4 Angstrom.
    • Total energy convergence: < 5 x 10-6 eV/atom.
    • Maximum force on atom: < 0.01 eV/Angstrom.

Commercial Applications

Section titled “Commercial Applications”

The calculated properties suggest several high-value engineering and industrial applications for these novel carbon allotropes:

  • Photoelectric Devices and Solar Energy:

    • TY Carbon, T Carbon, and Cubane-diyne are candidates for next-generation solar cell absorbers. Their absorption coefficients in the visible region are comparable to or higher than standard materials like GaAs and Diamond-Si.
    • The direct band gaps of TY Carbon (2.2 eV) and T Carbon (3.2 eV) are ideal for efficient light emission and absorption, overcoming the limitations of indirect gap materials like silicon and diamond in optoelectronics.

  • High-Performance Mechanical Components:

    • Diamond and Supercubane exhibit extremely high Bulk, Shear, and Young’s moduli, confirming their suitability for use as superhard materials in cutting tools, industrial abrasives, and high-pressure anvils.

  • Thermal Management and Heat Sinks:

    • Diamond’s exceptionally high Debye temperature (2224.84 K) confirms its role as the premier material for thermal dissipation in high-power density electronics (e.g., RF amplifiers, CPUs) where efficient heat removal is critical.

  • Anisotropy Engineering:

    • Highly anisotropic materials like Cubane-yne (Emax/Emin ratio of 2.94) could be utilized in specialized sensors or structural components where a predictable, directional mechanical response is required, such as in micro-electro-mechanical systems (MEMS).
View Original Abstract

Based on first-principle calculations, the mechanical anisotropy and the electronic and optical properties of seven kinds of carbon materials are investigated in this work. These seven materials have similar structures: they all have X-type structures, with carbon atoms or carbon clusters at the center and stacking towards the space. A calculation of anisotropy shows that the order of elastic anisotropy in terms of the shear modulus, Young’s modulus and Poisson’s ratio of these seven carbon materials with similar structure is diamond < supercubane < T carbon < Y carbon < TY carbon < cubane-diyne < cubane-yne. As these seven carbon materials exhibit cubic symmetry, Young’s modulus has the same anisotropy in some major planes, so the order of elastic anisotropy in the Young’s modulus of these seven main planes is (111) plane < (001) plane = (010) plane = (100) plane < (011) plane = (110) plane = (101) plane. It is also due to the fact that their crystal structure has cubic symmetry that the elastic anisotropy in the shear modulus and the Poisson’s ratio of these seven carbon materials on the seven major planes are the same. Among the three propagation directions of [100], [110], and [111], the [110] propagation direction’s anisotropic ratio of the sound velocity of TY carbon is the largest, while the anisotropic ratio of the sound velocity of cubane-diyne on the [100] propagation direction is the smallest. In addition, not surprisingly, the diamond has the largest Debye temperature, while the TY carbon has the smallest Debye temperature. Finally, TY carbon, T carbon and cubane-diyne are also potential semiconductor materials for photoelectric applications owing to their higher or similar absorption coefficients to GaAs in the visible region.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2020 - Prediction of a novel carbon allotrope from first-principle calculations: A potential superhard material in monoclinic symmetry [Crossref]
  2. 2020 - PBCF-graphene: A 2D sp2 hybridized honeycomb carbon allotrope with a direct band gap [Crossref]
  3. 2016 - Three dimensional metallic carbon from distorting sp3-Bond [Crossref]
  4. 2011 - T-Carbon: A novel carbon allotrope [Crossref]
  5. 2017 - Pseudo-topotactic conversion of carbon nanotubes to T-carbon nanowires under picosecond laser irradiation in methanol [Crossref]
  6. 2012 - Carbon allotropes with triple bond predicted by first-principle calculation: Triple bond modified diamond and T-carbon [Crossref]
  7. 2015 - C2/m-carbon: Structural, mechanical, and electronic properties [Crossref]
  8. 2020 - Five carbon allotropes from Squaroglitter structures [Crossref]
  9. 2019 - Two novel superhard carbon allotropes with honeycomb structures [Crossref]

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