scholarly journals Lattice thermal conductivity of Bi2Te3 and SnSe using Debye-Callaway and Monte Carlo phonon transport modeling: Application to nanofilms and nanowires

2019 ◽  
Vol 100 (11) ◽  
Author(s):  
Patricia Al-Alam ◽  
Gilles Pernot ◽  
Mykola Isaiev ◽  
David Lacroix ◽  
Melanie De Vos ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Transport Modeling

Analytical Model for Lattice Thermal Conductivity Predictions of Periodic Nanoporous Structures

2016 ◽  
Author(s):  
Qing Hao ◽  
Yue Xiao ◽  
Hongbo Zhao
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Kinetic Relationship ◽  
Wide Range ◽  
Edge Scattering ◽  
Bulk Phonon ◽  
Nanoporous Structures

Phonon transport within nanoporous bulk materials or thin films is of importance to applications in thermoelectrics, gas sensors, and thermal insulation materials. Considering classical phonon size effects, the lattice thermal conductivity KL can be predicted assuming diffusive pore-edge scattering of phonons and bulk phonon mean free paths. In the kinetic relationship, kL can be computed by modifying the phonon mean free paths with the characteristic length ΛPore of the porous structure. Despite some efforts using the Monte Carlo ray tracing method to extract ΛPore, the resulting KL often diverges from that predicted by phonon Monte Carlo simulations. In this work, the effective ΛPore is extracted by directly comparing the predictions by the kinetic relationship and phonon Monte Carlo simulations. The investigation covers a wide range of period sizes and volumetric porosities. In practice, these ΛPore values can be used for thermal analysis of general nanoporous materials.

A High Thermoelectric Performance ZT in p-Type LaSe2 Crystal

2021 ◽  
Vol 871 ◽  
pp. 203-207
Author(s):  
Jian Liu
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
High Power ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
High Power Factor ◽  
P Type

In this work, we use first principles DFT calculations, anharmonic phonon scatter theory and Boltzmann transport method, to predict a comprehensive study on the thermoelectric properties as electronic and phonon transport of layered LaSe2 crystal. The flat-and-dispersive type band structure of LaSe2 crystal offers a high power factor. In the other hand, low lattice thermal conductivity is revealed in LaSe2 semiconductor, combined with its high power factor, the LaSe2 crystal is considered a promising thermoelectric material. It is demonstrated that p-type LaSe2 could be optimized to exhibit outstanding thermoelectric performance with a maximum ZT value of 1.41 at 1100K. Explored by density functional theory calculations, the high ZT value is due to its high Seebeck coefficient S, high electrical conductivity, and low lattice thermal conductivity .

scholarly journals Thermal transport in nanocrystalline Si and SiGe by ab initio based Monte Carlo simulation

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Lina Yang ◽  
Austin J. Minnich
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Ab Initio ◽  
Grain Boundaries ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Computational Study ◽  
Phonon Transport ◽  
Nanocrystalline Si

Abstract Nanocrystalline thermoelectric materials based on Si have long been of interest because Si is earth-abundant, inexpensive, and non-toxic. However, a poor understanding of phonon grain boundary scattering and its effect on thermal conductivity has impeded efforts to improve the thermoelectric figure of merit. Here, we report an ab-initio based computational study of thermal transport in nanocrystalline Si-based materials using a variance-reduced Monte Carlo method with the full phonon dispersion and intrinsic lifetimes from first-principles as input. By fitting the transmission profile of grain boundaries, we obtain excellent agreement with experimental thermal conductivity of nanocrystalline Si [Wang et al. Nano Letters 11, 2206 (2011)]. Based on these calculations, we examine phonon transport in nanocrystalline SiGe alloys with ab-initio electron-phonon scattering rates. Our calculations show that low energy phonons still transport substantial amounts of heat in these materials, despite scattering by electron-phonon interactions, due to the high transmission of phonons at grain boundaries, and thus improvements in ZT are still possible by disrupting these modes. This work demonstrates the important insights into phonon transport that can be obtained using ab-initio based Monte Carlo simulations in complex nanostructured materials.

First-Principles Study on Mn-Doped TiFeSb Half-Heusler Thermoelectric Materials

2013 ◽  
Vol 762 ◽  
pp. 471-475 ◽  
Author(s):  
Zhong Hong Lai ◽  
Jian Ma ◽  
Jing Chuan Zhu
Keyword(s):  
Thermal Conductivity ◽  
Density Of States ◽  
Thermoelectric Materials ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Mechanical Stability ◽  
Electronic Conductivity ◽  
Phonon Transport ◽  
Doping Amount ◽  
Mn Doped

The 8.33at% Mn-doped TiFeSb half-heusler thermoelectric materials were studied by first-principles in this paper. The space occupying of Mn atoms in Mn-doped TiFeSb system was studied according to thermodynamic stability, mechanical stability, and density of states at the Fermi level. The results show that Mn atoms would substitute Ti atoms preferentially at 8.33at% doping amount. The electronic and phonon transport properties were calculated in TiFeSb and (Ti0.75Mn0.25)FeSb to characterize their electronic and thermal conductivity. The results indicate that Mn-doping can increase the power factor due to improving the electronic conductivity while reducing the lattice thermal conductivity. Therefore, the (Ti0.75Mn0.25)FeSb are expected to show better thermoelectric properties than TiFeSb.

Monte Carlo Modeling of Phonon Transport Using Scattering Phase Functions

2008 ◽  
Author(s):  
Neil Zuckerman ◽  
Jennifer R. Lukes
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Numerical Methods ◽  
Ballistic Transport ◽  
Simulation Method ◽  
Phonon Transport ◽  
Nanometer Scale ◽  
Boltzmann Transport ◽  
Length Scales ◽  
Scale Structures

The calculation of heat transport in nonmetallic materials at small length scales is important in the design of thermoelectric and electronic materials. New designs with quantum dot superlattices (QDS) and other nanometer-scale structures can change the thermal conductivity in ways that are difficult to model and predict. The Boltzmann Transport Equation can describe the propagation of energy via mechanical vibrations in an analytical fashion but remains difficult to solve for the problems of interest. Numerical methods for simulation of propagation and scattering of high frequency vibrational quanta (phonons) in nanometer-scale structures have been developed but are either impractical at micron length scales, or cannot truly capture the details of interactions with nanometer-scale inclusions. Monte Carlo (MC) models of phonon transport have been developed and demonstrated based on similar numerical methods used for description of electron transport [1-4]. This simulation method allows computation of thermal conductivity in materials with length scales LX in the range of 10 nm to 10 μm. At low temperatures the model approaches a ballistic transport simulation and may function for even larger length scales.

Theoretical Thermal Conductivity of Periodic Two-Dimensional Nanocomposites

2003 ◽  
Vol 793 ◽  
Author(s):  
Ronggui Yang ◽  
Gang Chen
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
High Efficiency ◽  
Transport Model ◽  
Cell Interaction ◽  
Phonon Transport ◽  
Two Dimensional ◽  
Boltzmann Transport ◽  
Volumetric Fraction ◽  
Strong Function

ABSTRACTA phonon Boltzmann transport model is established to study the lattice thermal conductivity of nanocomposites with nanowires embedded in a host semiconductor material. Special attention has been paid to cell-cell interaction using periodic boundary conditions. The simulation shows that the temperature profiles in nanocomposites are very different from those in conventional composites, due to ballistic phonon transport at nanoscale. The thermal conductivity of periodic 2-D nanocomposites is a strong function of the size of the embedded wires and the volumetric fraction of the constituent materials. At constant volumetric fraction the smaller the wire diameter, the smaller is the thermal conductivity of periodic two-dimensional nanocomposites. For fixed silicon wire dimension, the lower the atomic percentage of germanium, the lower the thermal conductivity of the nanocomposites. The results of this study can be used to direct the development of high efficiency thermoelectric materials.

Curvature Effect on the Thermal Conductivity of Nanowires

2008 ◽  
Author(s):  
Liang-Chun Liu ◽  
Mei-Jiau Huang ◽  
Ronggui Yang
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Effective Thermal Conductivity ◽  
Silicon Nanowires ◽  
Phonon Transport ◽  
Curvature Effect ◽  
Transport Efficiency ◽  
Directional Preference ◽  
Monte Carlo Simulator ◽  
Thermal Conductivities

Directional preference of the ballistic phonon transport plays an important role in the effective thermal conductivity of nanostructures. Curved nanowires can have very different thermal conductivities from straight ones. In this work, a Monte-Carlo simulator is developed and used to investigate the curvature effect on the phonon transport in silicon nanowires. The results show that the curvature of geometry does not alter the phonon transport efficiency in large wires but decreases the effective thermal conductivity in their nano-sized counterparts.

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