Mode confinement, interface mass-smudging, and sample length effects on phonon transport in thin nanocomposite superlattices

Srivastava, G. P.; Thomas, Iorwerth O.

doi:10.1088/1361-648x/aaf4c4

Cited by 4 publications

(8 citation statements)

References 43 publications

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“…Region R2 (D ∼ Λ) : κ = κ(a suitable effective medium expression), For ultra short period nanocomposites, we calculate κ(D << Λ) using our semi-ab initio approach for the DFT-Boltzmann based conductivity tensor [11,20] and a generalised version of Callaway's anharmonic phonon relaxation time expression [19] using phonon eigensolutions generated using Density Funtional Peturbation Theory [21]. A recap of the essential features is presented in Appendix A.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

“…Phonon eigensolutions required for the thermal conductivity calculations were generated using the Quantum Espresso package [21] with parameters defined in previous studies [11,20,30]; some quantitative corrections from previously reported thermal conductivity results are due to this study's work using the correct eigenvalue input as per recent work [26].…”

Section: Generation Of Phonon Eigensolutionsmentioning

confidence: 99%

“…Phonon scattering rates from isotopic mass defects and crystal anharmonicity in bulk materials and for ultra short period nanocomposites were calculated using the procedure described in our previous publications [11,20].…”

Section: Computation Of Mass Defect and Anharmonic Scatteringsmentioning

confidence: 99%

“…The phonon relaxation rate due to interface mass smudging (IMS) in ultra short period nanocomposites is computed by employing the perturbative scheme of treating mass defects as explained in a previous work [11]. Specifically, we considered IF mass swapping using the Gaussian distribution of the type exp(−j 2 ζ) where ζ is a parameter determining the amount j 2 ζ of mass swap in the jth interface layer.…”

Section: Computation Of Ims Scatteringmentioning

confidence: 99%

“…Indeed, no such study as far as we are aware has yet been performed. A few first-principles-based attempts have been made, but due to heavy computational demands are restricted to period sizes in the low nanometer (nm) range [9][10][11]. In this work we employ a combination of the electronic density functional theory (DFT) and the phonon Boltzmann transport equation based semi-ab initio approach and a generalised and extended modification of effective medium approach (GemEMA) to study tunable thermal transport characteristics of composites of periodicities ranging from 1 nm to 100 µm, with particular emphasis on nanocomposites of periodicities in the range 1-100 nm.…”

Section: Introductionmentioning

confidence: 99%

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Tunable Thermal Transport Characteristics of Nanocomposites

Srivastava

Thomas

2020

Nanomaterials

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We present a study of tunable thermal transport characteristics of nanocomposites by employing a combination of a full-scale semi-ab inito approach and a generalised and extended modification of the effective medium theory. Investigations are made for planar superlattices (PSLs) and nanodot superlattices (NDSLs) constructed from isotropic conductivity covalent materials Si and Ge, and NDSLs constructed from anisotropic conductivity covalent-van der Waals materials MoS 2 and WS 2 . It is found that difference in the conductivities of individual materials, period size, volume fraction of insertion, and atomic-level interface quality are the four main parameters to control phonon transport in nanocomposite structures. It is argued that the relative importance of these parameters is system dependent. The equal-layer thickness Si/Ge PSL shows a minimum in the room temperature conductivity for the period size of around 4 nm, and with a moderate amount of interface mass smudging this value lies below the conductivity of SiGe alloy.

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Section: Theoretical Frameworkmentioning

confidence: 99%

Section: Generation Of Phonon Eigensolutionsmentioning

confidence: 99%

Section: Computation Of Mass Defect and Anharmonic Scatteringsmentioning

confidence: 99%

Section: Computation Of Ims Scatteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tunable Thermal Transport Characteristics of Nanocomposites

Srivastava

Thomas

2020

Nanomaterials

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Effect of interface density, quality and period on the lattice thermal conductivity of nanocomposite materials

Thomas

Srivastava

2020

Journal of Applied Physics

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We examine the effects of interface density, quality, and period size on the lattice thermal conductivity of nanocomposite materials within the framework of a recently developed extended modified effective medium approach. A density functional theory and Boltzmann equation based semi-ab initio approach is used to calculate the constituent thermal conductivities, and the effective thermal boundary conductance is computed by modeling interface roughness based on a realistic combination of acoustic mismatch and diffuse mismatch contributions, for systems with anisotropic (directionally dependent) and isotropic thermal conductivities. Results obtained for Si/Ge and MoS2/WS2 systems indicate that the effective cross-planar thermal conductivity of planar superlattice systems is closely related to the thermal boundary resistance of the system for small superlattice periods, whereas in nanodot superlattices, the effective thermal conductivity for small particles is primarily regulated through the effective scattering lengths used in the calculation of the insert and matrix conductivities.

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Tuning the interfacial friction force and thermal conductance by altering phonon properties at contact interface

Dong¹,

Ding²,

Zhou³

et al. 2022

Nanotechnology

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Controlling friction force and thermal conductance at solid/solid interface is of great importance but remains a significant challenge. In this work, we propose a method to control the matching degree of phonon spectra at the interface through modifying the atomic mass of contact materials, thereby regulating the interfacial friction force and thermal conductance. Results of Debye theory and molecular dynamics simulations show that the cutoff frequency of phonon spectrum decreases with increasing atomic mass. Thus, two contact surfaces with equal atomic mass have same vibrational characteristics, so that more phonons could pass through the interface. In these regards, the coupling strength of phonon modes on contact surfaces makes it possible to gain insight into the nonmonotonic variation of interfacial friction force and thermal conductance. Our investigations suggest that the overlap of phonon modes increases energy scattering channels and therefore phonon transmission at the interface, and finally, an enhanced energy dissipation in friction and heat transfer ability at interface.

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Mode confinement, interface mass-smudging, and sample length effects on phonon transport in thin nanocomposite superlattices

Cited by 4 publications

References 43 publications

Tunable Thermal Transport Characteristics of Nanocomposites

Tunable Thermal Transport Characteristics of Nanocomposites

Effect of interface density, quality and period on the lattice thermal conductivity of nanocomposite materials

Tuning the interfacial friction force and thermal conductance by altering phonon properties at contact interface

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