Thermal Transport Measurements of Bilayer and Few-Layer Graphene Supported on Silicon Dioxide

2011 ◽  
Author(s):  
Mir Mohammad Sadeghi ◽  
Li Shi
Keyword(s):  
Thermal Conductivity ◽  
Silicon Dioxide ◽  
Thermal Conductance ◽  
Layer Graphene ◽  
Scattering Effects ◽  
Before And After ◽  
Linear Rise ◽  
Opposite Behavior ◽  
Few Layer Graphene ◽  
Sio2 Support

The thermal conductivity of bilayer graphene (BLG) and few-layer graphene (FLG) samples supported on a silicon dioxide (SiO2) bridge has been measured in the temperature range between 80 K and 375 K. In the experiments, resistance heater and thermometer lines at the two ends of the bridge were used to implement steady-state thermal conductance measurements of the sample before and after the graphene on the bridge was etched away. The obtained thermal conductivity of the supported graphene increases and the temperature for the peak thermal conductivity decreases with increasing layer thickness. Compared to the reported thermal conductivity of suspended FLG samples, the opposite behavior observed here for the supported FLG reveals that interaction with the SiO2 support and also possibly polymer residue on top of the FLG sample suppresses the thermal conductivity of the supported FLG more than interlayer interaction within the FLG. The linear rise of thermal conductivity with layer number up to 8 layers suggests that the scattering effects due to substrate and polymer residue penetrates much more than 4 layers into a multilayer flake.

Thermal Conductivity Reduction in Few-Layer Graphene

2011 ◽  
Author(s):  
Dhruv Singh ◽  
Jayathi Y. Murthy ◽  
Timothy S. Fisher
Keyword(s):  
Thermal Conductivity ◽  
Weak Coupling ◽  
Phonon Scattering ◽  
Single Layer ◽  
Acoustic Mode ◽  
Single Layer Graphene ◽  
Boltzmann Transport ◽  
Layer Graphene ◽  
Out Of Plane ◽  
Few Layer Graphene

Using the linearized Boltzmann transport equation and perturbation theory, we analyze the reduction in the intrinsic thermal conductivity of few-layer graphene sheets accounting for all possible three-phonon scattering events. Even with weak coupling between layers, a significant reduction in the thermal conductivity of the out-of-plane acoustic modes is apparent. The main effect of this weak coupling is to open many new three-phonon scattering channels that are otherwise absent in graphene. The highly restrictive selection rule that leads to a high thermal conductivity of ZA phonons in single-layer graphene is only weakly broken with the addition of multiple layers, and ZA phonons still dominate thermal conductivity. We also find that the decrease in thermal conductivity is mainly caused by decreased contributions of the higher-order overtones of the fundamental out-of-plane acoustic mode. Moreover, the extent of reduction is largest when going from single to bilayer graphene and saturates for four layers. The results compare remarkably well over the entire temperature range with measurements of of graphene and graphite.

Substrate Effects on the Thermal Conductivity of Single Layer Supported Graphene

2011 ◽  
Author(s):  
Z. Wei ◽  
C. Dames ◽  
Y. Chen
Keyword(s):  
Thermal Conductivity ◽  
Silicon Dioxide ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Dynamics Model ◽  
Graphene Flake ◽  
Substrate Effects ◽  
Layer Graphene ◽  
Lennard Jones ◽  
Non Equilibrium Molecular Dynamics

A non-equilibrium molecular dynamics model is developed to calculate the thermal conductivity of single layer graphene supported on silicon dioxide. We use the Tersoff potential to describe the carbon-carbon interactions within graphene, and a Lennard-Jones (LJ) potential to describe the interactions between graphene and silicon dioxide. To overcome possible artifacts of thermal expansion, the model avoids using any periodic or fixed boundary conditions for the graphene flake. For both smooth and rough substrates, the simulations show that increasing the LJ coupling strength between graphene and substrate can reduce the in-plane thermal conductivity of graphene. We also investigated the effects of roughness. The simulations show that the thermal conductivity is sensitive to the roughness only when the coupling is large. These results indicate how the thermal properties of graphene may be modified by adjusting the coupling and roughness of the substrate.

Thermal conductivity of suspended few-layer graphene by a modified T-bridge method

2013 ◽  
Vol 103 (13) ◽  
pp. 133102 ◽  
Author(s):  
W. Jang ◽  
W. Bao ◽  
L. Jing ◽  
C. N. Lau ◽  
C. Dames
Keyword(s):  
Thermal Conductivity ◽  
Layer Graphene ◽  
Bridge Method ◽  
Few Layer Graphene

scholarly journals Interfacial coupling effects on the thermal conductivity of few-layer graphene

2020 ◽  
Vol 7 (9) ◽  
pp. 095602
Author(s):  
Yajing Kan ◽  
Feng Hong ◽  
Zhiyong Wei ◽  
Kedong Bi
Keyword(s):  
Thermal Conductivity ◽  
Interfacial Coupling ◽  
Coupling Effects ◽  
Layer Graphene ◽  
Few Layer Graphene

Enhanced Thermal Transport of Nanostructured Phase Change Composite for Thermal Energy Storage

2014 ◽  
Author(s):  
Harish Sivasankaran ◽  
Yasuyuki Takata ◽  
Masamichi Kohno
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Effective Medium Theory ◽  
Graphene Nanoplatelets ◽  
Layer Graphene ◽  
Energy Storage Applications ◽  
Few Layer Graphene

The power dissipation capacity of organic phase change materials (PCM) which is used for thermal energy storage applications is hindered by its low thermal conductivity. In this work we demonstrate that inclusion of few layer graphene nanoplatelets dramatically increase the thermal conductivity of the PCM upon solidification. The dramatic thermal conductivity increase stems from the fact that the graphene nanoplatelets are entrapped within the grain boundaries upon solidification of the crystalline structures thereby increasing the percolation pathways. We also show that the enhancement in thermal conductivity is beyond the predictions of effective medium theory. The present work introduces an efficient way to enhance the thermal conductivity of nanocomposites using few layer graphene by effectively controlling the heat transport path simply upon solidification. Such a phase change material with enhanced thermal conductivity makes it a promising candidate for thermal energy storage applications.

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