Four-Probe Measurement of Thermal Transport in Suspended Few-Layer Graphene With Polymer Residue

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Eric Ou ◽  
Xun Li ◽  
Sangyeop Lee ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Thermal Transport ◽  
Thermal Contact ◽  
Experimental Studies ◽  
Phonon Transport ◽  
Contact Thermal Resistance ◽  
Layer Graphene ◽  
Scattering Rate ◽  
Transport Measurements ◽  
Polymeric Residue

The presence of unknown thermal contact thermal resistance has limited prior two-probe thermal transport measurements of suspended graphene samples. Here, we report four-probe thermal transport measurements of suspended seven-layer graphene. By isolating the thermal contact resistance, we are able to attribute the observed reduced thermal conductivity primarily to polymeric residue on the sample instead of the contact thermal resistance, which resulted in ambiguity in the prior experimental studies of the effect of polymer reside. The extrinsic scattering rate due to the polymer residue is extracted from the measurement results based on a solution of the Peierls-Boltzmann phonon transport equation.

Sensitivity of Thermal Transport in Uranium Dioxide to Fission Gas

2019 ◽  
Author(s):  
Katherine Mitchell ◽  
Hunter Horner ◽  
Alex Resnick ◽  
Jungkyu Park ◽  
Eduardo B. Farfán ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Uranium Dioxide ◽  
Thermal Transport ◽  
Temperature Drop ◽  
Phonon Transport ◽  
Interfacial Thermal Resistance ◽  
Large Temperature ◽  
Gas Bubble ◽  
Gas Generation ◽  
Fission Gas

Abstract Understanding the effect of fission gas generation on thermal resistance in various nuclear fuels is critical for managing fuel performance. Fission gas in the fuels degrades its thermal properties by altering the lattice vibrations. It results in thermal expansion that increases the thermal resistance and decreases the structural stability of the fuels. In this research, thermal transport in uranium dioxide is studied at a microscopic level when Xe and Kr gasses interact with uranium and oxygen atoms. Reverse non-equilibrium molecular dynamics (RNEMD) is used to calculate the thermal resistances and provide an understanding about the effect of the fission gas release on phonon transport. The results show that the thermal conductivity of uranium dioxide is decreased nearly by 78% by the presence of only one fission gas bubble. The thermal transport in uranium dioxide is shown to become highly diffusive by a single fission gas bubble and a large temperature drop in temperature profiles are observed in all simulation structures with fission gas bubbles. The average interfacial thermal resistance across a fission gas bubble is estimated to be 2.1 × 10−9 Km2/W.

scholarly journals Computational Study of In-Plane Phonon Transport in Si Thin Films

2014 ◽  
Vol 4 (1) ◽  
Author(s):  
Xinjiang Wang ◽  
Baoling Huang
Keyword(s):  
Thin Films ◽  
Thermal Transport ◽  
Computational Study ◽  
Isotope Effects ◽  
Phonon Transport ◽  
Phonon Confinement ◽  
Phonon Modes ◽  
Scattering Rate ◽  
Si Films ◽  
Thermal Conductivities

Abstract We have systematically investigated the in-plane thermal transport in Si thin films using an approach based on the first-principles calculations and lattice dynamics. The effects of phonon mode depletion induced by the phonon confinement and the corresponding variation in interphonon scattering, which may be important for the thermal conductivities of ultra-thin films but are often neglected in precedent studies, are considered in this study. The in-plane thermal conductivities of Si thin films with different thicknesses have been predicted over a temperature range from 80 K to 800 K and excellent agreements with experimental results are found. The validities of adopting the bulk phonon properties and gray approximation of surface specularity in thin film studies have been clarified. It is found that in ultra-thin films, while the phonon depletion will reduce the thermal conductivity of Si thin films, its effect is largely offset by the reduction in the interphonon scattering rate. The contributions of different phonon modes to the thermal transport and isotope effects in Si films with different thicknesses under various temperatures are also analyzed.

Measurements of the Intrinsic Thermal Conductivity of Individual Multi-Wall Carbon Nanotubes

2011 ◽  
Author(s):  
Juekuan Yang ◽  
Scott W. Waltermire ◽  
Yang Yang ◽  
Deyu Li ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Heat Source ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Experimental Studies ◽  
Contact Thermal Resistance ◽  
Multi Wall Carbon Nanotubes ◽  
The Past ◽  
Thermal Conductivities

Thermal transport through carbon nanotubes (CNTs) attracted a lot of attention over the past decade. Several experimental studies have been carried out to determine the thermal conductivities of CNTs [1–3]. However, the measurements are based on an individual CNT sample between two suspended membranes and the results actually include both the intrinsic thermal resistance of the CNT and the contact thermal resistance between the CNT and the two suspended membranes that serve as a heat source and a heat sink. Hence, the effective thermal conductivity extracted from these measurements should be lower than the intrinsic thermal conductivities of the CNTs measured. To minimize the contact thermal resistance, electron beam induce deposition (EBID) of different metals has been used to increase the contact area between the CNT and the heat source and sink [3,4]. However, it is still not clear how effective this treatment is and to what level the effective thermal conductivity obtained after the EBID treatment reflects the intrinsic one.

Thermal Transport in Nanostructured Solid-State Cooling Devices

2005 ◽  
Vol 127 (1) ◽  
pp. 108-114 ◽  
Author(s):  
Deyu Li ◽  
Scott T. Huxtable ◽  
Alexis R. Abramson ◽  
Arun Majumdar
Keyword(s):  
Thermal Conductivity ◽  
Solid State ◽  
Nanostructured Materials ◽  
Thermal Transport ◽  
Experimental Studies ◽  
Phonon Transport ◽  
Peltier Effect ◽  
Cooling Devices ◽  
Low Dimensional ◽  
Solid State Cooling

Low-dimensional nanostructured materials are promising candidates for high efficiency solid-state cooling devices based on the Peltier effect. Thermal transport in these low-dimensional materials is a key factor for device performance since the thermoelectric figure of merit is inversely proportional to thermal conductivity. Therefore, understanding thermal transport in nanostructured materials is crucial for engineering high performance devices. Thermal transport in semiconductors is dominated by lattice vibrations called phonons, and phonon transport is often markedly different in nanostructures than it is in bulk materials for a number of reasons. First, as the size of a structure decreases, its surface area to volume ratio increases, thereby increasing the importance of boundaries and interfaces. Additionally, at the nanoscale the characteristic length of the structure approaches the phonon wavelength, and other interesting phenomena such as dispersion relation modification and quantum confinement may arise and further alter the thermal transport. In this paper we discuss phonon transport in semiconductor superlattices and nanowires with regards to applications in solid-state cooling devices. Systematic studies on periodic multilayers called superlattices disclose the relative importance of acoustic impedance mismatch, alloy scattering, and crystalline imperfections at the interfaces. Thermal conductivity measurements of mono-crystalline silicon nanowires of different diameters reveal the strong effects of phonon-boundary scattering. Experimental results for Si/SiGe superlattice nanowires indicate that different phonon scattering mechanisms may disrupt phonon transport at different frequencies. These experimental studies provide insight regarding the dominant mechanisms for phonon transport in nanostructures. Finally, we also briefly discuss Peltier coolers made from nanostructured materials that have shown promising cooling performance.

scholarly journals An Improved Thermal Performance Modeling for High-speed Spindle of Machine Tool Based on Thermal Contact Resistance Analysis

2021 ◽  
Author(s):  
Bing Fang ◽  
Mengna Cheng ◽  
Tianqi Gu ◽  
Dapeng Ye
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
High Speed ◽  
Thermal Contact ◽  
Great Influence ◽  
Contact Thermal Resistance ◽  
Spindle System ◽  
Fea Model

Abstract The distribution of the temperature field has a great influence on structural performance, thermal deformation, thermal error compensation. To improve the prediction accuracy of the temperature distribution of the spindle system, a comprehensive model considering the contact thermal resistance (TCR) of the interfaces was established to analyze the thermal performance of high-speed spindle system in the present work. An elastoplastic contact model was used to calculate the contacting areas and loads of interfaces, which were employed to establish the contact thermal resistance model of the main interfaces of spindle, such as bearing rings and tool holders. Basing on the TCR parameters, a Finite Element Analysis (FEA) model was proposed to analyze the temperature distribution of the spindle system. And a temperature test experiment was set up to verify the accuracy of the FEA model. The results show that the relative error of representative test points was all less than 5%, which means the established model can appropriately reflect the temperature field distribution of the spindle.

On the existence and uniqueness of steady state solutions in thermoelastic contact with frictional heating

2005 ◽  
Vol 461 (2057) ◽  
pp. 1261-1282 ◽  
Author(s):  
L.-E Andersson ◽  
A Klarbring ◽  
J.R Barber ◽  
M Ciavarella
Keyword(s):  
Thermal Resistance ◽  
Existence And Uniqueness ◽  
Frictional Heating ◽  
Thermal Contact ◽  
Lipschitz Constant ◽  
Contact Thermal Resistance ◽  
Uniqueness Of Solutions ◽  
Lipschitz Continuous ◽  
Mathematical Problems ◽  
Three Space

It is well known that contact and friction in thermoelasticity result in mathematical problems which may lack solutions or have multiple solutions. Previously, issues related to thermal contact and issues related to frictional heating have been discussed separately. In this work, the two effects are coupled. Theorems of existence and uniqueness of solutions in two or three space dimensions are obtained—essentially extending, to frictional heating, results due to Duvaut, which were built on Barber's heat exchange conditions. Two qualitatively different existence results are given. The first one requires that the contact thermal resistance goes to zero at least as fast as the inverse of the contact pressure. The second existence theorem requires no such growth condition, but requires instead that the frictional heating, i.e. the sliding velocity times the friction coefficient, is small enough. Finally, it is shown that a solution is unique if the inverse of the contact thermal resistance is Lipschitz continuous and the Lipschitz constant, as well as the frictional heating, is small enough.

Thermal Conductance of Individual Single-Wall Carbon Nanotubes

2008 ◽  
Author(s):  
Michael T. Pettes ◽  
Li Shi
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Resistance ◽  
Phonon Scattering ◽  
Thermal Conductance ◽  
Phonon Transport ◽  
Single Wall Carbon Nanotubes ◽  
Platinum Resistance ◽  
Contact Thermal Resistance ◽  
Single Wall Carbon ◽  
Temperature Range

This work presents an experimental study of phonon transport in individual suspended single-wall carbon nanotubes (SWCNTs). Through the use of a micro fabricated device consisting of two adjacent suspended membranes, each with a platinum resistance heater and thermometer, the thermal conductance of several individual SWCNTs has been directly measured over the temperature range of 100 to 490 K. The effects of Umklapp phonon-phonon scattering remain weak and the thermal conductance remains roughly proportional to the calculated ballistic conductance throughout the temperature range. The macroscopic thermal conductance increases with temperature throughout the temperature range indicating static scattering processes or contact thermal resistance dominate transport in this regime. These results are an order of magnitude lower than the predicted ballistic thermal conductance calculated for a defect-free (18,0) nanotube. The results contrast with thermal conductance measurements reported using a high-bias DC self heating method. The discrepancy is discussed in terms of the differences in the contact thermal resistance, defects, and measurement methods.

scholarly journals Decoupling electron and phonon transport in single-nanowire hybrid materials for high-performance thermoelectrics

2021 ◽  
Vol 7 (20) ◽  
pp. eabe6000
Author(s):  
Lin Yang ◽  
Madeleine P. Gordon ◽  
Akanksha K. Menon ◽  
Alexandra Bruefach ◽  
Kyle Haas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Electrical Transport ◽  
High Performance ◽  
Figure Of Merit ◽  
Phonon Transport ◽  
Core Shell ◽  
Nanowire Diameter ◽  
High Performing ◽  
Polycrystalline Thin Films

Organic-inorganic hybrids have recently emerged as a class of high-performing thermoelectric materials that are lightweight and mechanically flexible. However, the fundamental electrical and thermal transport in these materials has remained elusive due to the heterogeneity of bulk, polycrystalline, thin films reported thus far. Here, we systematically investigate a model hybrid comprising a single core/shell nanowire of Te-PEDOT:PSS. We show that as the nanowire diameter is reduced, the electrical conductivity increases and the thermal conductivity decreases, while the Seebeck coefficient remains nearly constant—this collectively results in a figure of merit, ZT, of 0.54 at 400 K. The origin of the decoupling of charge and heat transport lies in the fact that electrical transport occurs through the organic shell, while thermal transport is driven by the inorganic core. This study establishes design principles for high-performing thermoelectrics that leverage the unique interactions occurring at the interfaces of hybrid nanowires.

scholarly journals A Thermal Transport Study of Branched Carbon Nanotubes with Cross and T-Junctions

2021 ◽  
Vol 11 (13) ◽  
pp. 5933
Author(s):  
Wei-Jen Chen ◽  
I-Ling Chang
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Thermal Management ◽  
Thermal Transport ◽  
Topological Defects ◽  
Branch Length ◽  
Phonon Transport ◽  
Heat Current ◽  
Transport Mechanisms ◽  
Non Equilibrium Molecular Dynamics

This study investigated the thermal transport behaviors of branched carbon nanotubes (CNTs) with cross and T-junctions through non-equilibrium molecular dynamics (NEMD) simulations. A hot region was created at the end of one branch, whereas cold regions were created at the ends of all other branches. The effects on thermal flow due to branch length, topological defects at junctions, and temperature were studied. The NEMD simulations at room temperature indicated that heat transfer tended to move sideways rather than straight in branched CNTs with cross-junctions, despite all branches being identical in chirality and length. However, straight heat transfer was preferred in branched CNTs with T-junctions, irrespective of the atomic configuration of the junction. As branches became longer, the heat current inside approached the values obtained through conventional prediction based on diffusive thermal transport. Moreover, directional thermal transport behaviors became prominent at a low temperature (50 K), which implied that ballistic phonon transport contributed greatly to directional thermal transport. Finally, the collective atomic velocity cross-correlation spectra between branches were used to analyze phonon transport mechanisms for different junctions. Our findings deeply elucidate the thermal transport mechanisms of branched CNTs, which aid in thermal management applications.

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