Heat current anticorrelation effects leading to thermal conductivity reduction in nanoporous Si

Oliveira, Laura de Sousa; Hosseini, S. Aria; Greaney, Alex; Neophytou, Neophytos

doi:10.1103/physrevb.102.205405

Cited by 13 publications

(19 citation statements)

References 46 publications

(67 reference statements)

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“…Accordingly, the running thermal conductivity κ (τ ) first increases with increasing τ , then develops a maximum value at τ max , and eventually decays to zero from the positive side, with fluctuations in the long-time limit due to increasing noise-to-signal ratio. Such 035417-3 peaks in the running thermal conductivity have been observed in other contexts, such as thermal transport in nanoporous silicon [33] and nonlocal thermal transport within the linearresponse formalism [34].…”

Section: Resultssupporting

confidence: 55%

Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations

et al. 2021

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We propose a way to properly interpret the apparent thermal conductivity obtained for finite systems using equilibrium molecular dynamics simulations (EMD) with fixed or open boundary conditions in the transport direction. In such systems the heat current autocorrelation function develops negative values after a correlation time which is proportional to the length of the simulation cell in the transport direction. Accordingly, the running thermal conductivity develops a maximum value at the same correlation time and eventually decays to zero. By comparing EMD with nonequilibrium molecular dynamics (NEMD) simulations, we conclude that the maximum thermal conductivity from EMD in a system with domain length 2L is equal to the thermal conductivity from NEMD in a system with domain length L. This facilitates the use of nonperiodic-boundary EMD for thermal transport in finite samples in close correspondence to NEMD.

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Section: Resultssupporting

confidence: 55%

Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations

et al. 2021

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“…Accordingly, the running thermal conductivity κ(τ ) first increases with increasing τ , then develops a maximum value at τ max , and eventually decays to zero from the positive side, with fluctuations in the long-time limit due to increasing noise-to-signal ratio. Such peaks in the running thermal conductivity have been observed in other contexts, such as thermal transport in nanoporous silicon [32] and nonlocal thermal transport within the linear-response formalism [33].…”

Section: Models and Methodssupporting

confidence: 53%

Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations

Dong,

Xiong,

Fan

et al. 2020

Preprint

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“…Nanoengineered membranes including thin films, 2,3 nanowires, 4 nanomeshes, 5,6 nanocomposites, 7,8 and nanoporous structures [9][10][11][12] feature extremely low thermal conductivity, sometimes beyond the amorphous limit. 13 This is largely due to the scattering of phonons with large MFPs (generally with small frequencies), i.e., those that are comparable with the characteristic length of the material.…”

Section: Introductionmentioning

confidence: 99%

“…13 This is largely due to the scattering of phonons with large MFPs (generally with small frequencies), i.e., those that are comparable with the characteristic length of the material. Low-thermal conductivity can also be obtained with point defects 14,15 , such as those induced by alloying, 13,16 and vacancies 12 . Point-defect scattering strongly suppresses medium-to high-frequency phonons, mostly with shorter MFPs while leaving low-frequency phonons (generally with longer MFPs) unimpeded.…”

Section: Introductionmentioning

confidence: 99%

Mode- and Space- Resolved Thermal Transport of Alloy Nanostructures

Hosseini¹,

Khanniche²,

Snyder³

et al. 2022

Preprint

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Nanostructured semiconducting alloys obtain ultra-low thermal conductivity as a result of the scattering of phonons with a wide range of mean-free-paths (MFPs). In these materials, long-MFP phonons are scattered at the nanoscale boundaries whereas short-MFP high-frequency phonons are impeded by disordered point defects introduced by alloying. While this trend has been validated by simplified analytical and numerical methods, an ab-initio space-resolved approach remains elusive. To fill this gap, we calculate the thermal conductivity reduction in porous alloys by solving the mode-resolved Boltzmann transport equation for phonons using the finite-volume approach. We analyze different alloys, length-scales, concentrations, and temperatures, obtaining a very large reduction in the thermal conductivity over the entire configuration space. For example, a ∼97% reduction is found for Al0.8In0.2As with 25% porosity. Furthermore, we employ these simulations to validate our recently introduced "Ballistic Correction Model" (BCM), an approach that estimates the effective thermal conductivity using the characteristic MFP of the bulk alloy and the length-scale of the material. The BCM is then used to provide guiding principles in designing alloy-based nanostructures. Notably, it elucidates how porous alloys such as SixGe1−x obtain larger thermal conductivity reduction compared to porous Si or Ge, while also explaining why we should not expect similar behavior in alloys such as AlxIn1−xAs. By taking into account the synergy from scattering at different scales, we provide a route for the design of materials with ultra-low thermal conductivity.

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Heat current anticorrelation effects leading to thermal conductivity reduction in nanoporous Si

Abstract: Please refer to published version for the most recent bibliographic citation information. If a published version is known of, the repository item page linked to above, will contain details on accessing it.

Cited by 13 publications

References 46 publications

Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations

Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations

Interpretation of apparent thermal conductivity in finite systems from equilibrium molecular dynamics simulations

Mode- and Space- Resolved Thermal Transport of Alloy Nanostructures

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