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Orientation dependent thermal conductance in single-layer MoS2.

Jiang JW, Zhuang X, Rabczuk T - Sci Rep (2013)

Bottom Line: Particularly, the thermal conductivity for the armchair MoS2 nanoribbon is about 673.6 Wm(-1) K(-1) in the armchair nanoribbon, and 841.1 Wm(-1) K(-1) in the zigzag nanoribbon at room temperature.By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS2 nanoribbon in the frequency range of [150, 200] cm(-1).Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS2 nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.

View Article: PubMed Central - PubMed

Affiliation: Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstr. 15, D-99423 Weimar, Germany.

ABSTRACT
We investigate the thermal conductivity in the armchair and zigzag MoS2 nanoribbons, by combining the non-equilibrium Green's function approach and the first-principles method. A strong orientation dependence is observed in the thermal conductivity. Particularly, the thermal conductivity for the armchair MoS2 nanoribbon is about 673.6 Wm(-1) K(-1) in the armchair nanoribbon, and 841.1 Wm(-1) K(-1) in the zigzag nanoribbon at room temperature. By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS2 nanoribbon in the frequency range of [150, 200] cm(-1). Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS2 nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.

No MeSH data available.


Related in: MedlinePlus

Top: the transmission functions for armchair and zigzag MSNRs.Note obvious less transmission channels in the armchair MSNR in [150, 200] cm−1. Bottom: the thermal conductivity (κ) obtained from thermal conductance (σ) through their relationship, κ = σL/s, with cross-sectional area s = wh. The thickness h = 6.033 Å, and the length L = 1 μm. σ is calculated by the Landauer formula.
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f3: Top: the transmission functions for armchair and zigzag MSNRs.Note obvious less transmission channels in the armchair MSNR in [150, 200] cm−1. Bottom: the thermal conductivity (κ) obtained from thermal conductance (σ) through their relationship, κ = σL/s, with cross-sectional area s = wh. The thickness h = 6.033 Å, and the length L = 1 μm. σ is calculated by the Landauer formula.

Mentions: Fig. 3 top panel shows the transmission functions for the armchair and zigzag MSNRs. These functions exhibit some regular steps, due to the absence of phonon-phonon scattering. In the ballistic transport, σ is proportional to the cross-sectional area, since there are more channels available for heat delivery in thicker nanoribbons. However, the thermal conductance from equation (1) does not depend on the length of the system. σ can be used to get the thermal conductivity (κ) of a MSNR with arbitrary length L: κ = σL/s, where s is the cross-sectional area. We have assumed the thickness of the MSNR to be 6.033 Å, which is the space between two adjacent layers in the bulk MoS28. This thickness value is the same for both armchair and zigzag MSNRs, so its value does not affect our comparison for their thermal conductivity. It is quite obvious that the thermal conductivity does not depend on the cross section. It means that the thermal conductivity in the MSNR does not depend on its width, since the thickness is a constant. On the other hand, the thermal conductivity in ballistic region increases linearly with increasing length, which has been observed in the thermal conductivity of two-dimensional graphene2730313233. In the experiment, the thermal conductivity is measured for a MSNR sample of dimension around μm9. Hence, we will predict the thermal conductivity for a MSNR of length L = 1.0 μm.


Orientation dependent thermal conductance in single-layer MoS2.

Jiang JW, Zhuang X, Rabczuk T - Sci Rep (2013)

Top: the transmission functions for armchair and zigzag MSNRs.Note obvious less transmission channels in the armchair MSNR in [150, 200] cm−1. Bottom: the thermal conductivity (κ) obtained from thermal conductance (σ) through their relationship, κ = σL/s, with cross-sectional area s = wh. The thickness h = 6.033 Å, and the length L = 1 μm. σ is calculated by the Landauer formula.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3713516&req=5

f3: Top: the transmission functions for armchair and zigzag MSNRs.Note obvious less transmission channels in the armchair MSNR in [150, 200] cm−1. Bottom: the thermal conductivity (κ) obtained from thermal conductance (σ) through their relationship, κ = σL/s, with cross-sectional area s = wh. The thickness h = 6.033 Å, and the length L = 1 μm. σ is calculated by the Landauer formula.
Mentions: Fig. 3 top panel shows the transmission functions for the armchair and zigzag MSNRs. These functions exhibit some regular steps, due to the absence of phonon-phonon scattering. In the ballistic transport, σ is proportional to the cross-sectional area, since there are more channels available for heat delivery in thicker nanoribbons. However, the thermal conductance from equation (1) does not depend on the length of the system. σ can be used to get the thermal conductivity (κ) of a MSNR with arbitrary length L: κ = σL/s, where s is the cross-sectional area. We have assumed the thickness of the MSNR to be 6.033 Å, which is the space between two adjacent layers in the bulk MoS28. This thickness value is the same for both armchair and zigzag MSNRs, so its value does not affect our comparison for their thermal conductivity. It is quite obvious that the thermal conductivity does not depend on the cross section. It means that the thermal conductivity in the MSNR does not depend on its width, since the thickness is a constant. On the other hand, the thermal conductivity in ballistic region increases linearly with increasing length, which has been observed in the thermal conductivity of two-dimensional graphene2730313233. In the experiment, the thermal conductivity is measured for a MSNR sample of dimension around μm9. Hence, we will predict the thermal conductivity for a MSNR of length L = 1.0 μm.

Bottom Line: Particularly, the thermal conductivity for the armchair MoS2 nanoribbon is about 673.6 Wm(-1) K(-1) in the armchair nanoribbon, and 841.1 Wm(-1) K(-1) in the zigzag nanoribbon at room temperature.By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS2 nanoribbon in the frequency range of [150, 200] cm(-1).Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS2 nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.

View Article: PubMed Central - PubMed

Affiliation: Institute of Structural Mechanics, Bauhaus-University Weimar, Marienstr. 15, D-99423 Weimar, Germany.

ABSTRACT
We investigate the thermal conductivity in the armchair and zigzag MoS2 nanoribbons, by combining the non-equilibrium Green's function approach and the first-principles method. A strong orientation dependence is observed in the thermal conductivity. Particularly, the thermal conductivity for the armchair MoS2 nanoribbon is about 673.6 Wm(-1) K(-1) in the armchair nanoribbon, and 841.1 Wm(-1) K(-1) in the zigzag nanoribbon at room temperature. By calculating the Caroli transmission, we disclose the underlying mechanism for this strong orientation dependence to be the fewer phonon transport channels in the armchair MoS2 nanoribbon in the frequency range of [150, 200] cm(-1). Through the scaling of the phonon dispersion, we further illustrate that the thermal conductivity calculated for the MoS2 nanoribbon is esentially in consistent with the superior thermal conductivity found for graphene.

No MeSH data available.


Related in: MedlinePlus