3ω
           method for specific heat and thermal conductivity measurements

Lu, Lixin; Wang, Yi; Zhang, D. L.

doi:10.1063/1.1378340

Cited by 401 publications

(286 citation statements)

References 10 publications

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“…Connecting the copper wires at opposite ends of the sample to two independent heating blocks allows a temperature gradient across the crystal to determine the Seebeck coefficient as described by Chaikin and Kwak [19] . Measurement of the thermal conductivity was attained by means of the 3ω-method at self-heating geometry for rodlike samples of high surface-to-volume ratio [20,21] . Feeding an AC-current, 0 sin( ), into the sample via the outer contacts results in a temperature and resistance oscillation of doubled frequency for materials with a temperature-dependent resistivity of the form = [22,23] .…”

Section: Low-cost and Sustainable Organic Thermoelectrics Based On Lomentioning

confidence: 99%

Low‐Cost and Sustainable Organic Thermoelectrics Based on Low‐Dimensional Molecular Metals

et al. 2017

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk 1 DOI: 10.1002/((please add manuscript number)) Article type: Communication Low-Cost and Sustainable Organic Thermoelectrics Based on LowDimensional Molecular MetalsBy Florian Huewe*, Alexander Steeger*, Kalina Kostova, Laurence Burroughs, Irene Bauer, Peter Strohriegl, Vladimir Dimitrov, Simon Woodward and Jens Pflaum* F. Huewe [ †] , A. Steeger [ †] The dimensionless figure of merit measures a material's thermoelectric performancewhere electrical conductivity (resistivity ), Seebeck coefficient/thermopower , and thermal conductivity provide the power factor = 2 . Materials with high electrical conductivity and thermopower but low thermal conductivity are desirable to maximize and hence, the thermoelectric conversion efficiency. Approximately, is inversely proportional to which in turn is related to the electronic thermal conductivity el = via the Wiedemann-Franz (WF) law.Advances in have been achieved by tuning the doping of semiconductors to maximize the [6] together with reducing the phononic contribution to thermal conduction by means of nanostructured superlattice architectures [7,8] . To overcome the inherent limitations of ordinary materials, a dimensionality reduction of the electronic system has been proposed [9] . This can lead to a violation of the WF law [10,11] and to phonon drag contributions to the thermopower [12] . Complex crystal structures, e.g. Zintl compounds [13] and skutterudites [14] , have been evaluated as good thermoelectric 3 candidates due to reduced lattice thermal conductivity and electronic band structure tunability. These optimization strategies, together with the ability for low-cost production and low-temperature processibility, have recently raised interest in organic polymers [15] , such as PEDOT:Tos, reaching = 0.25 at room temperature (RT) [4] and thus advancing the value of = 1.2 obtained for Bi2Te3 (the best RT thermoelectric material to date [7] ). Herein, quasi-1D organic conductors based on small molecules constitute a new, sustainable approach towards organic thermoelectrics that provide many of the desired electrical and thermal properties described above. Additionally, they are lightweight and thermodynamically stable allowing for portable device manufacturing and long-term usage. In comparison to organic polymers the availability of electrically high-performing p-and ntype organic conductors facilitates the construction of all-organic thermoelectric devices.As a starting point we chose two of the best p-and n-type conducting radical ion salts, TTT2I3 (TTT = Tetrathiotetracene) and (DMe-DCNQI)2Cu (DMe-DCNQI = Dimethyl-Dicyanoquinonediimine).They form macroscopic needle-like sin...

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Section: Low-cost and Sustainable Organic Thermoelectrics Based On Lomentioning

confidence: 99%

Low‐Cost and Sustainable Organic Thermoelectrics Based on Low‐Dimensional Molecular Metals

et al. 2017

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“…At each temperature and frequency, 10 ac voltage measurements are taken and averaged to increase measurement accuracy. According to the analytical expression given by Lu et al, 3 as frequency decreases, the RMS 3ω voltage should gradually increase and then asymptotically approach a frequency independent value. Figure 3D,F,H,J shows the RMS 3ω voltage as a function of input current frequency for samples with different coating thicknesses.…”

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“…The agreement between experiments and theory is further verified by observing the relationship,V 3ω,RMS ∼ I RMS 3 , for several samples as shown in Figure S3 in the Supporting Information. 26 According to the series solution described by Lu et al, 3 the thermal conductivity in the low frequency limit is given by eq 1…”

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Measurement of Thermal Conductivity of PbTe Nanocrystal Coated Glass Fibers by the 3ω Method

et al. 2013

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Fiber-based thermoelectric materials can conform to curved surfaces to form energy harvesting devices for waste heat recovery. Here we investigate the thermal conductivity in the axial direction of glass fibers coated with lead telluride (PbTe) nanocrystals using the self-heated 3ω method particularly at low frequency. While prior 3ω measurements on wire-like structures have only been demonstrated for high thermal conductivity materials, the present work demonstrates the suitability of the 3ω method for PbTe nanocrystal coated glass fibers where the low thermal conductivity and high aspect ratio result in a significant thermal radiation effect. We simulate the experiment using a finite-difference method that corrects the thermal radiation effect and extract the thermal conductivity of glass fibers coated by PbTe nanocrystals. The simulation method for radiation correction is shown to be generally much more accurate than analytical methods. We explore the effect of nanocrystal volume fraction on thermal conductivity and obtain results in the range of 0.50−0.93 W/mK near room temperature. KEYWORDS: Thermoelectric, flexible, thermal conductivity, 3ω, radiation, finite difference method F lexible thermoelectric materials such as nanocomposites 1 and fibers 2 can significantly impact waste heat recovery and solid-state cooling because of the advantages of lightweight, flexibility, and higher tolerance to thermal expansion. Particularly, flexibility can allow thermoelectric devices to be installed on curved surfaces such as automobile exhaust pipes, power plant steam pipes, manufacturing industry cooling pipes, and so forth. Our previous studies 2 showed that thermoelectric fibers made from glass fibers coated with an ultrathin layer of PbTe nanocrystals (300 nm thick) can possess a similar thermoelectric figure of merit compared to traditional rigid bulk bismuth telluride modules. The module assemblies require several millimeters of thickness, which highlights a great potential for high performance with much reduced raw material cost for the coated fibers. In this paper, we present an investigation of the thermal conductivity of our thermoelectric fibers at the single fiber level using the 3ω method to further understand the thermal transport in the axial direction. Through simulations based on the finite-difference method, we successfully model the radiation effect and extract the thermal conductivity at the single fiber level. Our simulation method for radiation correction appears to be much more accurate than conventional analytical methods. Furthermore, we measure and simulate several samples to determine the thermal conductivities of composite fibers of varying composition; from 0% PbTe to 35.8% PbTe by volume fraction.Several methods have been developed to measure the thermal properties of wire-like samples in the axial direction. These include the self-heating 3ω method, 3 dc thermal bridge

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“…Instead of a horizontal bundle suspended over a vacuum gap, 21 a vertical bundle between two electrodes in a (presumable vacuum) opening was measured. This allows direct measurement of the as-grown vertical bundles.…”

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confidence: 99%

Thermal conductivity of low temperature grown vertical carbon nanotube bundles measured using the three-ω method

Vollebregt

Banerjee

Beenakker

et al. 2013

Applied Physics Letters

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The thermal conductivity of as-grown vertical multi-walled carbon nanotubes (CNT) bundles fabricated at low temperature (500 C) was measured using a vertical 3x-method. For this, CNT were selectively grown inside an oxide opening and sandwiched between two metal electrodes. The validity of the method was confirmed by both measurements as simulations. The measured thermal conductivity of 1.7-3.5 W/mK is significantly lower than values reported before, which is caused by the low quality of the tubes. This clearly indicates that tube quality will be essential when integrating CNT. V C 2013 AIP Publishing LLC. [http://dx

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3ω method for specific heat and thermal conductivity measurements

Cited by 401 publications

References 10 publications

Low‐Cost and Sustainable Organic Thermoelectrics Based on Low‐Dimensional Molecular Metals

Low‐Cost and Sustainable Organic Thermoelectrics Based on Low‐Dimensional Molecular Metals

Measurement of Thermal Conductivity of PbTe Nanocrystal Coated Glass Fibers by the 3ω Method

Thermal conductivity of low temperature grown vertical carbon nanotube bundles measured using the three-ω method

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