Thermal conductivity in metallic nanostructures at high temperature: Electrons, phonons, and the Wiedemann-Franz law

Stojanović, Nenad; Maithripala, D. H. S.; Berg, Jordan M.; Holtz, M.

doi:10.1103/physrevb.82.075418

Cited by 241 publications

(145 citation statements)

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“…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.…”

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

et al. 2017

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“…The behaviors of phonon scattering at interfaces have been very well studied in the past. 7,[16][17][18][19][20][21][22][23][24][25] Generally, the energy is totally transmitted in a single or perfect crystal. Meanwhile, the phonons are strongly scattered at the GB, where a significant amount of total energy is reflected due to the discontinuity in the structure between two crystals.…”

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Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection

Barışık

Kim

2016

The Journal of Chemical Physics

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This study focuses on the proper characterization of temperature profiles across grain boundaries (GBs) in order to calculate the correct interfacial thermal resistance (ITR) and reveal the influence of GB geometries onto thermal transport. The solid-solid interfaces resulting from the orientation difference between the (001), (011), and (111) copper surfaces were investigated. Temperature discontinuities were observed at the boundary of grains due to the phonon mismatch, phonon backscattering, and atomic forces between dissimilar structures at the GBs. We observed that the temperature decreases gradually in the GB area rather than a sharp drop at the interface. As a result, three distinct temperature gradients developed at the GB which were different than the one observed in the bulk solid. This behavior extends a couple molecular diameters into both sides of the interface where we defined a thickness at GB based on the measured temperature profiles for characterization. Results showed dependence on the selection of the bin size used to average the temperature data from the molecular dynamics system. The bin size on the order of the crystal layer spacing was found to present an accurate temperature profile through the GB. We further calculated the GB thickness of various cases by using potential energy (PE) distributions which showed agreement with direct measurements from the temperature profile and validated the proper binning. The variation of grain crystal orientation developed different molecular densities which were characterized by the average atomic surface density (ASD) definition. Our results revealed that the ASD is the primary factor affecting the structural disorders and heat transfer at the solid-solid interfaces. Using a system in which the planes are highly close-packed can enhance the probability of interactions and the degree of overlap between vibrational density of states (VDOS) of atoms forming at interfaces, leading to a reduced ITR. Thus, an accurate understanding of thermal characteristics at the GB can be formulated by selecting a proper bin size. Published by AIP Publishing. [http://dx

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“…Така примусова орієнтація наповнювача дозволяє збільшити анізотропію складу, а отже, пріоритетні напрями для тепло-та електричного транспорту створюються уздовж напрямку зовнішнього силового поля. Це має знайти важливе застосування для теплозбереження у будівництві, в теплообмінниках та пристроях теплової дисипації в електроніці, де задана теплопровідність у певному напрямку відіграє визначальну роль [5,6]. Ці підходи є дуже привабливими завдяки простій орієнтації функціонального наповнювача в потрібних напрямках [7 -9] і такі матеріали часто називають "інтелектуальними" [10,11].…”

Section: вступunclassified

Вплив зовнішнього магнітного поля на структуроутворення та транспортні властивості полімерних композитів на основі епоксидного полімеру та Fe3O4

Korskanov¹,

Dolgoshey²,

Shantaliy³

et al. 2017

CSL

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Influence of an external magnetic field on the structure formation and transport properties of polymeric composites based on epoxy and Fe3O4, 3(36), doi: 10.26909/csl.3.2017.4 In this paper, the results of the study of the influence of an external magnetic field on the thermal and electrically conductive properties of composites based on epoxy and magnetite are presented. Different types of fillers or amplifiers have been developed to obtain composite materials with desirable thermal, mechanical and electrical properties. Fillers play an important retrofitting role in improving the efficiency of polymers and production efficiency.The samples of the initial epoxy polymer (EP) and composites based on EP and magnetite (Fe3O4) were obtained. To obtain the samples, an epoxidian oligomer (EDO) based on bisphenol A was used, with a density of 1150 kg / m 3 at a temperature of 293 K (DER 321 trademark of DOW Chemical). As a curing agent for EDO, Polypox H354 (manufacturer of UPPC (Germany)) was used. As a filler, magnetite (Fe3O4) with a density of 5200 kg/m 3 with a conductivity of 10 -4 ÷10 -2 S/m and a particle size of 1÷5 μm was selected. Such samples were formed under the action of an external magnetic field and without it. It is found that the formation of a composite under the influence of an external magnetic field leads to the formation of continuous channels from ferromagnetic particles of Fe3O4 in a continuous matrix of EP. It is established that, despite of the high intrinsic electrical conductivity of Fe3O4, the presence of continuous filler channels does not contribute significantly to the resistivity of composites due to high intercontact resistance within the filler channels. The thermal conductivity in the direction of the orientation of the Fe3O4 particles increases substantially. This means that the electrical conductivity of such composites determines the conductivity of the polymer matrix. At the same time, the specific resistance of the composite of the same gross composition in the direction along the direction of the magnetic field of the filler is much lower, but in absolute value remains rather high.Key words: polymeric composites, magnetic field, thermal conductivity.Вплив зовнішнього магнітного поля на структуроутворення та транспортні властивості полімерних композитів на основі епоксидного полімеру та Fe3O4 -Київський національний університет архітектури і будівництва, Київ, УкраїнаРазработаны различные типы наполнителей или усилителей для получения композитных материалов с желательными тепловыми, механическими и электрическими свойствами. Наполнители играют важную переоснащающую роль в повышении эффективности полимеров и эффективности производства. Получены образцы исходного эпоксидного полимера (ЭП) и композитов на основе ЭП и магнетита (Fe3O4), сформированных под действием внешнего магнитного поля и без него. Обнаружено, что формирование композита под действием внешнего магнитного поля приводит к образованию непрерывных каналов из ферромагнитных частиц Fe3O4 в сплошной матрице ЭП. Уст...

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Thermal conductivity in metallic nanostructures at high temperature: Electrons, phonons, and the Wiedemann-Franz law

Cited by 241 publications

References 26 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

Atomic density effects on temperature characteristics and thermal transport at grain boundaries through a proper bin size selection

Вплив зовнішнього магнітного поля на структуроутворення та транспортні властивості полімерних композитів на основі епоксидного полімеру та Fe3O4

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