Molecular dynamics study of the lattice thermal conductivity of Kr/Ar superlattice nanowires

Chen, Yunfei; Li, Deyu; Yang, Juekuan; Wu, Yingjie; Lukes, Jennifer R.; Majumdar, Arun

doi:10.1016/j.physb.2004.03.247

Cited by 97 publications

(77 citation statements)

References 33 publications

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“…The similar periodic length dependent thermal conductivity was also observed in Kr/Ar superlattice NWs. 78 In addition to the random and interface scatterings of phonon, the surface scattering is another way to reduce thermal conductivity. It has been demonstrated that thermal conductivity of NWs can be reduced further obviously by introducing more surface scattering: making SiNWs hollow to create inner surface, i.e.…”

Section: A 1d Nanostructuresmentioning

confidence: 99%

Thermal transport in nanostructures

et al. 2012

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This review summarizes recent studies of thermal transport in nanoscaled semiconductors. Different from bulk materials, new physics and novel thermal properties arise in low dimensional nanostructures, such as the abnormal heat conduction, the size dependence of thermal conductivity, phonon boundary/edge scatterings. It is also demonstrated that phonons transport super-diffusively in low dimensional structures, in other words, Fourier's law is not applicable. Based on manipulating phonons, we also discuss envisioned applications of nanostructures in a broad area, ranging from thermoelectrics, heat dissipation to phononic devices.

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Section: A 1d Nanostructuresmentioning

confidence: 99%

Thermal transport in nanostructures

et al. 2012

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“…In the past two decades, molecular dynamics (MD) simulations have been employed extensively to study the interface thermal conductance across various material interfaces, [5][6][7][8][9][10][11][12][13] such as Kr/Ar, 7 Si/In, 11 carbon nanotube/Si, 12 Si/polymer 9 and PbTe/GeTe. 13 A relatively good understanding of the reduced lattice thermal conductivity in nanostructured materials due to the thermal boundary resistance has been obtained.…”

Section: Introductionmentioning

confidence: 99%

Effect of lattice mismatch on phonon transmission and interface thermal conductance across dissimilar material interfaces

Yang

2012

Phys. Rev. B

139

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When phonons transport across a material interface, they experience reflection, transmission and mode conversion, which results in a local temperature jump at interface and thus dramatically changes the thermal conductivity of nanostructured materials. Phonon transmission across lattice-matched interfaces has been studied extensively in recent years with the atomistic Green's function (AGF) approach, which usually uses one unit cell to represent the cross-section along the interface. However, modeling phonon transmission across realistic material interfaces is much more challenging because realistic interfaces are usually latticemismatched ones with atomic reconstruction, defects, and species mixing, which demands a larger cross-sectional area for the AGF simulation. In this paper, an integrated molecular dynamics (MD) and AGF approach is developed to study the phonon transmission across latticemismatched interfaces. MD simulation is used to simulate atomic reconstruction close to the 1 Email: Ronggui.Yang@Colorado.Edu interface. The recursive AGF approach is then employed for the first time to calculate frequencydependent phonon transmission across lattice-mismatched interfaces with defects and species mixing, which addresses the numerical challenge in calculating phonon transmission for a relatively large cross-sectional area with reduced computational cost. The study of the relaxed interface formed from two semi-infinite bulk materials shows that lattice mismatch increases the lattice disorder and decreases the adhesion energy, which in turn lowers phonon transmission and reduces the interface thermal conductance across lattice-mismatched interfaces. Low-frequency phonons can be significantly scattered by increasing the defect size across the interface while high frequency phonons can be scattered almost completely (phonon transmission <0.1) across an alloyed layer as thin as 2.27 nm. The effect of lattice-mismatch on phonon transmission becomes smaller for interfaces with defects and species mixing. The effect of annealing temperature on the Si/Ge interface thermal conductance was studied. A significant reduction of the Si/Ge interface thermal conductance was observed for a lattice-mismatched interface when annealed at high temperature, which agrees well with the available experimental data in literature.

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“…κ l can be calculated by multiplying the interface thermal conductance G by d, G = tυC 4 , t is the interfacial phonon transmission coefficient, and υ and C the average phonon velocity and the specific heat of two phases, respectively [19]. Therefore,…”

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Thermal conductivity of composites with nanoscale inclusions and size-dependent percolation

Liang¹,

Wei²,

Li³

2008

J. Phys.: Condens. Matter

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An analytical model for thermal conductivity of composites with nanoparticles in a matrix is developed based on the effective medium theory by introducing the intrinsic size effect of thermal conductivity of nanoparticles and the interface thermal resistance effect between two phases. The model predicts the percolation of thermal conductivity with the volume fraction change of the second phase, and the percolation threshold depends on the size and the shape of the nanoparticles. The theoretical predictions are in agreement with the experimental results.(Some figures in this article are in colour only in the electronic version)Nanocomposites have a wide range of applications in the fields of optoelectronics, thermoelectrics, sensors, etc, due to their novel structure and properties [1][2][3], such as nonlinear optical properties of granular metal-dielectric composites [2] and the large enhancement of effective thermal conductivity of a fluid with the addition of a small amount of carbon nanotubes [3]. With continuous miniaturization of semiconductor and microelectronic devices, thermal transport and heat management problems have begun to attract a great deal of attention [4,5].Some devices such as computer processors and integrated circuits need high thermal conductivity, which is favorable for getting the heat away. On the other hand, for thermal barriers and thermoelectric devices, low thermal conductivity is desired. Studies have found that thermal conductivity of nanowires and thin films is size-dependent, it is lower than the corresponding bulk value [6]. However, there are not many theoretical studies on the thermal conductivity of nanocomposites, despite its importance in applications [1,3].The effective medium theory (EMT) is often used to study the physical properties of composites, such as dielectric constant [2], thermal conductivity and electrical conductivity [7]; the percolation of electrical conductivity is usually found, but there are few reports on the percolation of thermal conductivity. The role of interface thermal resistance (ITR) in the thermal conductivity of nanocomposites was emphasized in recent studies [8,9], which improves the theoretical results based on the EMT, but the related work seems to be discussed only for the dilute limit [9]. Moreover, the intrinsic size effect of the thermal conductivity of nanoscale structures was not considered for composites based on the EMT. The study based on the Boltzmann transport equation considered both the interface and the size effects, but no percolation of thermal conductivity was found for nanocomposites [8]. In this paper, a general theoretical model about the effective thermal conductivity of nanocomposites in the whole range of volume fractions of the second phases is proposed based on the EMT by introducing both the intrinsic size effect and the ITR effect. The model predicts the percolation of the thermal conductivity for composites with nanoparticles or nanorods of smaller size.Based on quantum scattering theory and the Green's f...

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Molecular dynamics study of the lattice thermal conductivity of Kr/Ar superlattice nanowires

Cited by 97 publications

References 33 publications

Thermal transport in nanostructures

Thermal transport in nanostructures

Effect of lattice mismatch on phonon transmission and interface thermal conductance across dissimilar material interfaces

Thermal conductivity of composites with nanoscale inclusions and size-dependent percolation

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