Role of geometry and surface roughness in reducing phonon mean free path and lattice thermal conductivity of modulated nanowires

2020 ◽  
Vol 156 ◽  
pp. 119818
Author(s):  
Takuma Hori
Keyword(s):  
Thermal Conductivity ◽  
Surface Roughness ◽  
Free Path ◽  
Lattice Thermal Conductivity ◽  
Mean Free Path

Anisotropy in lattice thermal conductivity tensor of bulk hexagonal-MT2 (M = W, Mo and T = S and Se) by first principles phonon calculations

RSC Advances ◽  
2016 ◽  
Vol 6 (10) ◽  
pp. 7817-7828 ◽  
Author(s):  
Yingchun Ding ◽  
Min Chen ◽  
Bing Xiao
Keyword(s):  
Thermal Conductivity ◽  
Free Path ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Mean Free Path ◽  
Conductivity Tensor ◽  
Thermal Conductivity Tensor

Anisotropies in phonon mean free path and thermal conductivity as a function of temperature are calculated for 2H-MT2 structures.

scholarly journals Anisotropic intrinsic lattice thermal conductivity of phosphorene from first principles

2015 ◽  
Vol 17 (7) ◽  
pp. 4854-4858 ◽  
Author(s):  
Guangzhao Qin ◽  
Qing-Bo Yan ◽  
Zhenzhen Qin ◽  
Sheng-Ying Yue ◽  
Ming Hu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Free Path ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Mean Free Path

The intrinsic lattice thermal conductivity and the representative phonon mean free path of phosphorene.

Ioffe–Regel limit and lattice thermal conductivity reduction of high performance (AgSbTe2)15(GeTe)85 thermoelectric materials

2014 ◽  
Vol 2 (9) ◽  
pp. 3251-3256 ◽  
Author(s):  
Tiejun Zhu ◽  
Hongli Gao ◽  
Yi Chen ◽  
Xinbing Zhao
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Free Path ◽  
Thermoelectric Materials ◽  
High Performance ◽  
Lattice Thermal Conductivity ◽  
State Of The Art ◽  
Mean Free Path ◽  
Lattice Parameter ◽  
Fine Grained

This work shows that the carrier mean free path of TAGS-85 thermoelectric materials is comparable to the lattice parameter, and that refining the grain size will not affect the mobility while benefiting the thermal conductivity reduction. A state-of-the-art ZT of ~ 1.6 is obtained for the fine-grained samples.

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

scholarly journals Ballistic Heat Transport in Nanocomposite: The Role of the Shape and Interconnection of Nanoinclusions

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1982
Author(s):  
Paul Desmarchelier ◽  
Alice Carré ◽  
Konstantinos Termentzidis ◽  
Anne Tanguy
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Free Path ◽  
Mean Free Path ◽  
Strong Increase ◽  
Moderate Increase ◽  
Energy Propagation ◽  
The Mean ◽  
Dynamics Simulations

In this article, the effect on the vibrational and thermal properties of gradually interconnected nanoinclusions embedded in an amorphous silicon matrix is studied using molecular dynamics simulations. The nanoinclusion arrangement ranges from an aligned sphere array to an interconnected mesh of nanowires. Wave-packet simulations scanning different polarizations and frequencies reveal that the interconnection of the nanoinclusions at constant volume fraction induces a strong increase of the mean free path of high frequency phonons, but does not affect the energy diffusivity. The mean free path and energy diffusivity are then used to estimate the thermal conductivity, showing an enhancement of the effective thermal conductivity due to the existence of crystalline structural interconnections. This enhancement is dominated by the ballistic transport of phonons. Equilibrium molecular dynamics simulations confirm the tendency, although less markedly. This leads to the observation that coherent energy propagation with a moderate increase of the thermal conductivity is possible. These findings could be useful for energy harvesting applications, thermal management or for mechanical information processing.

Experiments on the flow of heat in liquid helium below 0.7 °K

1958 ◽  
Vol 246 (1246) ◽  
pp. 390-405 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Liquid Helium ◽  
Free Path ◽  
Empirical Relation ◽  
Mean Free Path ◽  
Series Of Experiments ◽  
The Mean ◽  
Set Up ◽  
Low Pressures ◽  
Measured Thermal Conductivity

A series of experiments has been performed to study the steady flow of heat in liquid helium in tubes of diameter 0.05 to 1.0 cm at temperatures between 0.25 and 0.7 °K. The results are interpreted in terms of the flow of a gas of phonons, in which the mean free path λ varies with temperature, and may be either greater or less than the diameter of the tube d . When λ ≫ d the flow is limited by the scattering of the phonons at the walls, and the effect of the surface has been studied, but when λ ≪ d viscous flow is set up in which the measured thermal conductivity is increased above that for wall scattering. This behaviour is very similar to that observed in the flow of gases at low pressures, and by applying kinetic theory to the problem it can be shown that the mean free path of the phonons characterizing viscosity can be expressed by the empirical relation λ = 3.8 x 10 -3 T -4.3 cm. This result is inconsistent with the temperature dependence of λ as T -9 predicted theoretically by Landau & Khalatnikov (1949).

Role of neutral-particle bombardment in dust–dust interactions in plasmas

2001 ◽  
Vol 65 (4) ◽  
pp. 257-272 ◽  
Author(s):  
Ya. K. KHODATAEV ◽  
G. E. MORFILL ◽  
V. N. TSYTOVICH
Keyword(s):  
Free Path ◽  
Particle Bombardment ◽  
Neutral Particle ◽  
Mean Free Path ◽  
Dust Particles ◽  
Neutral Particles ◽  
Additional Force ◽  
Numerical Coefficient ◽  
The Mean

It is shown that the interaction of dust with neutral plasma particles can lead to attractive forces between dust particles, both in the case where the distance between dust particles is less than the mean free path of neutral particles and in the case where it is greater. The expressions for attractive forces differs in the two limits only by a numerical coefficient. The additional force of dust interaction is found to be due to the neutrals created by recombination of charged plasma particles on the surface of dust particles. The influence of radiative dust cooling on dust–dust interaction is considered.

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