Phonon scattering and thermal conductance properties in two coupled graphene nanoribbons modulated with bridge atoms

2014 ◽  
Vol 378 (28-29) ◽  
pp. 1952-1955 ◽  
Author(s):  
Shi-Hua Tan ◽  
Li-Ming Tang ◽  
Ke-Qiu Chen
Keyword(s):  
Phonon Scattering ◽  
Graphene Nanoribbons ◽  
Thermal Conductance

scholarly journals Effects of Divacancy and Extended Line Defects on the Thermal Transport Properties of Graphene Nanoribbons

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1609 ◽  
Author(s):  
Min Luo ◽  
Bo-Lin Li ◽  
Dengfeng Li
Keyword(s):  
Transport Properties ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Low Frequency ◽  
Impurity Scattering ◽  
Low Frequencies ◽  
Thermal Transport Properties ◽  
Line Defects

The effects of divacancy, including isolated defects and extended line defects (ELD), on the thermal transport properties of graphene nanoribbons (GNRs) are investigated using the Nonequilibrium Green’s function method. Different divacancy defects can effectively tune the thermal transport of GNRs and the thermal conductance is significantly reduced. The phonon scattering of a single divacancy is mostly at high frequencies while the phonon scattering at low frequencies is also strong for randomly distributed multiple divacancies. The collective effect of impurity scattering and boundary scattering is discussed, which makes the defect scattering vary with the boundary condition. The effect on thermal transport properties of a divacancy is also shown to be closely related to the cross section of the defect, the internal structure and the bonding strength inside the defect. Both low frequency and high frequency phonons are scattered by 48, d5d7 and t5t7 ELD. However, the 585 ELD has almost no influence on phonon scattering at low frequency region, resulting in the thermal conductance of GNRs with 585 ELD being 50% higher than that of randomly distributed 585 defects. All these results are valuable for the design and manufacture of graphene nanodevices.

Electron–Phonon Scattering Is Much Weaker in Carbon Nanotubes than in Graphene Nanoribbons

2019 ◽  
Vol 10 (22) ◽  
pp. 7179-7187 ◽  
Author(s):  
Guoqing Zhou ◽  
Chao Cen ◽  
Shuyi Wang ◽  
Mingsen Deng ◽  
Oleg V. Prezhdo
Keyword(s):  
Carbon Nanotubes ◽  
Phonon Scattering ◽  
Graphene Nanoribbons ◽  
Electron Phonon Scattering

Strained effects on the thermal conductance of flexural and in-plane modes in graphene nanoribbons

2019 ◽  
Vol 33 (31) ◽  
pp. 1950383
Author(s):  
Bengang Bao ◽  
Gao-Hua Liao ◽  
Jun He ◽  
Chang-Ning Pan
Keyword(s):  
Transport Properties ◽  
Phonon Mode ◽  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Low Frequency ◽  
Phonon Transport ◽  
Frequency Region ◽  
Function Approach ◽  
Non Equilibrium Green’S Function ◽  
Plane Mode

Ballistic thermal transport properties in graphene nanoribbon modulated with strain are investigated by non-equilibrium Green’s function approach. The results show that the strain can suppress the phonon transport of flexural phonon mode (FPM) and enhance the phonon transport of in-plane mode (IPM) in low-frequency region, leading to the reduction in the thermal conductance of FPM and the enhancement in the thermal conductance of IPM. The total thermal conductance is decreased by strain as the reduction in the thermal conductance of FPM overcomes the enhancement in the thermal conductance of IPM.

scholarly journals Mechanisms governing phonon scattering by topological defects in graphene nanoribbons

2015 ◽  
Vol 27 (5) ◽  
pp. 055401 ◽  
Author(s):  
Ziming Zhu ◽  
Xiaolong Yang ◽  
Mingyuan Huang ◽  
Qingfeng He ◽  
Guang Yang ◽  
...  
Keyword(s):  
Phonon Scattering ◽  
Graphene Nanoribbons ◽  
Topological Defects

scholarly journals Impurity Substitution Enhances Thermoelectric Figure of Merit in Zigzag Graphene Nanoribbons

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Saeideh Ramezani Akbarabadi ◽  
Mojtaba Madadi Asl
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Electrical Conductance ◽  
Thermal Conductance ◽  
Simultaneous Increase ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Zigzag Graphene Nanoribbons

The thermoelectric properties of zigzag graphene nanoribbons (ZGNRs) are sensitive to chemical modification. In this study, we employed density functional theory (DFT) combined with the nonequilibrium green’s function (NEGF) formalism to investigate the thermoelectric properties of a ZGNR system by impurity substitution of single and double nitrogen (N) atoms into the edge of the nanoribbon. N-doping changes the electronic transmission probability near the Fermi energy and suppresses the phononic transmission. This results in a modified electrical conductance, thermal conductance, and thermopower. Ultimately, simultaneous increase of the thermopower and suppression of the electron and phonon contributions to the thermal conductance leads to the significant enhancement of the figure of merit in the perturbed (i.e., doped) system compared to the unperturbed (i.e., nondoped) system. Increasing the number of dopants not only changes the nature of transport and the sign of thermopower but also further suppresses the electron and phonon contributions to the thermal conductance, resulting in an enhanced thermoelectric figure of merit. Our results may be relevant for the development of ZGNR devices with enhanced thermoelectric efficiency.

Topological symmetry-induced width dependence of thermal conductance of edge-reconstructed graphene nanoribbons

2014 ◽  
Vol 47 (26) ◽  
pp. 265303 ◽  
Author(s):  
Jinghua Lan ◽  
Yongqing Cai ◽  
Gang Zhang ◽  
Jian-Sheng Wang ◽  
Yong-Wei Zhang
Keyword(s):  
Graphene Nanoribbons ◽  
Thermal Conductance

Thermal conductance attributed to phonon and electron in graphene nanoribbon

2014 ◽  
Vol 28 (18) ◽  
pp. 1450116 ◽  
Author(s):  
En-Jia Ye ◽  
Yi-Jian Shi ◽  
Lihong Shi ◽  
Xuean Zhao
Keyword(s):  
Low Temperature ◽  
Heat Transport ◽  
Energy Band ◽  
Function Method ◽  
Energy Transport ◽  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Square Lattice ◽  
Heat Current ◽  
Electron Contribution

In this work, the energy transport of phonon and electron in graphene nanoribbons (GNRs) are investigated by the nonequilibrium Green's function method without considering the interaction of phonon and electron. The heat current of phonon contribution comes from the gradient of temperature. While for the electron contribution, it stems from the gradient of both temperature and electrochemical potential. The corresponding intermediate functions satisfy the Onsager relationship. Thermal conductances are calculated in GNR and compared to those in square lattice ribbon model respectively. It is found that both the phonon and electron thermal conductances in square lattice ribbon are smaller than those in GNRs at low temperature and surpass those in armchair and zigzag GNRs respectively, as the temperature increases. Meanwhile, the heat transport is related to the edges of GNRs. These phenomena depend on their dispersion relations and energy band structures.

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