Thermal Rectification in Three-Dimensional Asymmetric Nanostructure

Lee, Jonghoon; Varshney, Vikas; Roy, Ajit K.; Ferguson, J. B.; Farmer, Barry L.

doi:10.1021/nl301006y

Cited by 69 publications

(71 citation statements)

References 14 publications

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“…4 Phonon localization was suggested to play a role as well. 12,13 Recently, TR was also predicted to occur in asymmetric pristine carbon nanostructures, 13−17 which are composed of a single material and are attractive for their simple structure and high thermal conductance. 18 However, the origin of TR in such homogeneous nanostructures remains unclear.…”

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confidence: 99%

“…28 TR due to phonon spectra mismatch resulting from device−thermostat interactions was reported in a diamond nanopyramid. 12 If the width increases to macroscopic size, the local phonon spectra will only depend on the temperature, and the phonon spectra overlap will be the same before and after switching the thermostats; thus TR vanishes. In contrast, the difference in phonon spectra overlap across interface in heterojunctions 4,11,26,27 is enabled by two different materials, not by the confined lateral dimension.…”

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confidence: 99%

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Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures

et al. 2014

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We show that thermal rectification (TR) in asymmetric graphene nanoribbons (GNRs) is originated from phonon confinement in the lateral dimension, which is a fundamentally new mechanism different from that in macroscopic heterojunctions. Our molecular dynamics simulations reveal that, though TR is significant in nanosized asymmetric GNRs, it diminishes at larger width. By solving the heat diffusion equation, we prove that TR is indeed absent in both the total heat transfer rate and local heat flux for bulk-size asymmetric single materials, regardless of the device geometry or the anisotropy of the thermal conductivity. For a deeper understanding of why lateral confinement is needed, we have performed phonon spectra analysis and shown that phonon lateral confinement can enable three possible mechanisms for TR: phonon spectra overlap, inseparable dependence of thermal conductivity on temperature and space, and phonon edge localization, which are essentially related to each other in a complicated manner. Under such guidance, we demonstrate that other asymmetric nanostructures, such as asymmetric nanowires, thin films, and quantum dots, of a single material are potentially high-performance thermal rectifiers. KEYWORDS: Thermal rectification, phonon lateral confinement, phonon localization, edge/surface effect, molecular dynamics, phonon spectra I nspired by the impact of electric diodes on the electronics industry, extensive attention has been given to the search of rectification of various other transport processes.1−3 Thermal rectification (TR) is a diode-like behavior where the heat current changes in magnitude when the applied temperature (T) bias is reversed in direction. A perfect thermal rectifier would be one that is highly thermal conductive in one direction while insulating in the other, and it is expected to work as a promising thermal management component of electronics as chip size continues decreasing or as a stand-alone thermally driven computing system replacing the electronic ones in certain conditions.Numerous studies have predicted or demonstrated the existence of TR in bulk or nanosized systems, most of which are heterojunctions (HJ) or graded systems.3−11 For twosegment systems, TR was usually attributed to the different Tdependence of the thermal conductivity (κ), 5,7 and for interfaces TR has been interpreted as the different phonon spectra mismatch before and after reversing the applied T bias. Phonon localization was suggested to play a role as well. 12,13 Recently, TR was also predicted to occur in asymmetric pristine carbon nanostructures, 13−17 which are composed of a single material and are attractive for their simple structure and high thermal conductance. 18 However, the origin of TR in such homogeneous nanostructures remains unclear. In this work, we have observed, using molecular dynamics and analytical derivations, that phonon confinement in the lateral dimension is required for TR to occur in asymmetric homogeneous structures made of a single material. We further show that...

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Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures

et al. 2014

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“…In the previous works [9,10,24,61], most of the authors have similar predictions that thermal conductivity decreases with the increasing aspect ratio. Different from their opinions, we suggest that thermal conductivities in positive direction and negative position do not increase with the aspect ratio at all times.…”

Section: Thermal Rectification Of Bamboo-like 3c-sic 4h-sicmentioning

confidence: 59%

“…To determine the boundary and interfacial effects of nanoscale structures, some groups have studied core-shell NWs [9], variable cross-section NWs [10,11], and rough NWs [12,13] in recent years. In thermal studies of SiC, Ni et al [14] and Chantrenne and Termentzidis calculated thermal conductivities and frequency density of states of (DOS) 3C-SiC and 6H-SiC NWs with constant cross-sections by the nonequilibrium molecular dynamics (NEMD) method [15].…”

Section: Introductionmentioning

confidence: 99%

Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Wang

2017

Journal of Nanomaterials

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Bamboo-like SiC nanowires (NWs) have specific geometric shapes, which have the potential to suppress thermal conductivity by phonon boundary scattering. In this work, phonon transport behaviors in the 3C-SiC, 4H-SiC, and 6H-SiC crystal lattices are studied by the Monte Carlo (MC) method, including impurity scattering, boundary scattering, and Umklapp scattering. Phonon relaxation times for Umklapp (U) scattering for the above three SiC polytypes are calculated from the respective phonon spectra, which have not been reported in the literature. Diffuse boundary scattering and thermal rectification with different aspect ratios are also studied at different temperatures. It is found that the thermal conductivities of the bamboo-like SiC polytypes can be lowered by two orders of magnitude compared with the bulk values by contributions from boundary scattering. Compared with bamboo-like 4H-SiC and 6H-SiC NWs, 3C-SiC has the largest U scattering relaxation rate and boundary scattering rate, which leads to its lowest thermal conductivities. The thermal conductivity in the positive direction is larger than that in the negative direction because of its lower boundary scattering relaxation rate.

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“…7 Other successful experimental findings are thermal rectifiers based on carbon or boron-nitride nanotubes with asymmetric mass loading, 8 and reduced graphene oxide. 9 A thermal rectifier should provide a large heat flow for a certain temperature gradient, but ideally be insulating when the direction of the gradient, and thus 10.1039/b000000x/ of the heat flow, is reversed. From a theoretical point of view, it has been found that thermal rectification in nanostructured systems sensitively depends on several parameters such as heat bath features, 10,11 the device geometry, 12,13 and on the interface properties between different materials inside the device.…”

Section: Introductionmentioning

confidence: 99%

Engineering thermal rectification in MoS₂nanoribbons: a non-equilibrium molecular dynamics study

et al. 2015

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Phononics in two-dimensional (2D) materials is an emergent field with a high potential impact from the basic as well as applied research points of view. Hereby it is crucial to provide strategies to control heat flow via atomic-scale engineering of the materials. In this study, thermal diodes made of single layer MoS 2 nanoribbons are investigated using non-equilibrium classical molecular dynamics. Specifically, we focus on the influence of shape asymmetries of the nanoribbons on the thermal current, and obtain thermal rectification ratios up to 30% for T-shaped nanoribbons. This behavior is then rationalized through a detailed analysis of the vibrational spectrum of the ribbons. In particular, it turns out that thermal rectification is mostly related to (i) the transversal finite size of the ribbon and (ii) to the different localization behavior of high-frequency modes for forward and backward heat flow directions. We expect our results to shed light on the potential of 2D materials for engineering highly efficient nanoscale thermal devices.

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Thermal Rectification in Three-Dimensional Asymmetric Nanostructure

Cited by 69 publications

References 14 publications

Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures

Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures

Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Engineering thermal rectification in MoS₂nanoribbons: a non-equilibrium molecular dynamics study

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Thermal Rectification in Three-Dimensional Asymmetric Nanostructure

Cited by 69 publications

References 14 publications

Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures

Phonon Lateral Confinement Enables Thermal Rectification in Asymmetric Single-Material Nanostructures

Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Engineering thermal rectification in MoS2nanoribbons: a non-equilibrium molecular dynamics study

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Engineering thermal rectification in MoS₂nanoribbons: a non-equilibrium molecular dynamics study