Predicting Thermal Transport in Bi2Te3: From Bulk to Nanostructures

2011 ◽  
Vol 1329 ◽  
Author(s):  
Bo Qiu ◽  
Xiulin Ruan
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Transport ◽  
Morse Potential ◽  
Density Functional ◽  
Energy Surface ◽  
Nanowire Diameter ◽  
Potential Form

ABSTRACTTwo-body interatomic potentials in the Morse potential form have been developed for bismuth telluride, and the potentials are used in molecular dynamics (MD) simulations to predict the thermal conductivity of Bi2Te3 bulk, nanowires and few-quintuple thin films. The density functional theory with local density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. Molecular dynamics simulations are then performed to predict the thermal conductivity of bulk Bi2Te3 at different temperatures, and the results agree with experimental data well. We also predicted the thermal conductivity of Bi2Te3 nanowires with diameter ranging from 3 to 30 nm with both smooth (SMNW) and rough (STNW) surfaces. It is found that when the nanowire diameter decreases to the molecular scale (below 10 nm, or the so called "quantum wire"), the thermal conductivity shows significant reduction as compared to bulk value. We find the dimensional crossover behavior of thermal transport in few quintuple layer (QL) thin films at room temperature, and we attribute it to the interplay between phonon Umklapp scattering and boundary scattering. Also, nanoporous films show significantly reduced thermal conductivity compared to perfect thin films, indicating that they can be very promising thermoelectric materials.

Molecular Dynamics Simulations of the Thermal Conductivity of Bismuth Telluride Using Two-Body Interatomic Potentials

2009 ◽  
Author(s):  
Bo Qiu ◽  
Xiulin Ruan
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Bismuth Telluride ◽  
Morse Potential ◽  
Energy Surface ◽  
Interatomic Potentials ◽  
Potential Form ◽  
Dynamics Simulations

Two-body interatomic potentials in the Morse potential form have been developed for bismuth telluride, and the potentials are used in molecular dynamics (MD) simulations to predict the thermal conductivity. The density functional theory with local density approximations is first used to calculate the total energies for many artificially distorted Bi2Te3 configurations to produce the energy surface. Then by fitting to this energy surface and other experimental data, the Morse potential form is parameterized. The fitted empirical interatomic potentials are shown to reproduce the elastic and phonon data well. Molecular dynamics simulations are then performed to predict the thermal conductivity of bulk Bi2Te3 at different temperatures, and the results agree with experimental data well.

Thermal Transport in Few-Quintuple Bi2Te3 Thin Films and Nanoribbons

2011 ◽  
Author(s):  
Bo Qiu ◽  
Xiulin Ruan
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Temperature Dependence ◽  
Thermal Transport ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Md Simulations ◽  
Boundary Scattering ◽  
Nanoporous Films

In this work, thermal conductivity of perfect and nanoporous few-quintuple Bi2Te3 thin films as well as nanoribbons with perfect and zig-zag edges is investigated using molecular dynamics (MD) simulations with Green-Kubo method. We find minimum thermal conductivity of perfect Bi2Te3 thin films with three quintuple layers (QLs) at room temperature, and we believe it originates from the interplay between inter-quintuple coupling and phonon boundary scattering. Nanoporous films and nanoribbons are studied for additional phonon scattering channels in suppressing thermal conductivity. With 5% porosity in Bi2Te3 thin films, the thermal conductivity is found to decrease by a factor of 4–6, depending on temperature, comparing to perfect single QL. For nanoribbons, width and edge shape are found to strongly affect the temperature dependence as well as values of thermal conductivity.

scholarly journals Thermal Transport Evolution Due to Nanostructural Transformations in Ga-Doped Indium-Tin-Oxide Thin Films

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1126
Author(s):  
Alexandr Cocemasov ◽  
Vladimir Brinzari ◽  
Do-Gyeom Jeong ◽  
Ghenadii Korotcenkov ◽  
Sergiu Vatavu ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Spray Pyrolysis ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Thermal Transport ◽  
Density Functional ◽  
Group Symmetry ◽  
Nanocrystalline Phase ◽  
Ga Doping

We report on a comprehensive theoretical and experimental investigation of thermal conductivity in indium-tin-oxide (ITO) thin films with various Ga concentrations (0–30 at. %) deposited by spray pyrolysis technique. X-ray diffraction (XRD) and scanning electron microscopy have shown a structural transformation in the range 15–20 at. % Ga from the nanocrystalline to the amorphous phase. Room temperature femtosecond time domain thermoreflectance measurements showed nonlinear decrease of thermal conductivity in the range 2.0–0.5 Wm−1 K−1 depending on Ga doping level. It was found from a comparison between density functional theory calculations and XRD data that Ga atoms substitute In atoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The calculated phonon dispersion relations revealed that Ga doping leads to the appearance of hybridized metal atom vibrations with avoided-crossing behavior. These hybridized vibrations possess shortened mean free paths and are the main reason behind the thermal conductivity drop in nanocrystalline phase. An evolution from propagative to diffusive phonon thermal transport in ITO:Ga with 15–20 at. % of Ga was established. The suppressed thermal conductivity of ITO:Ga thin films deposited by spray pyrolysis may be crucial for their thermoelectric applications.

Molecular Dynamics Modeling of Heat Transport in Metals and Semiconductors

2010 ◽  
Author(s):  
Sreekant Narumanchi ◽  
Kwiseon Kim
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Transport ◽  
Hybrid Electric Vehicle ◽  
Heat Dissipation ◽  
Phonon Dispersion ◽  
Interfacial Resistance ◽  
Dynamics Modeling ◽  
Molecular Dynamics Modeling

Interfacial thermal transport is of great importance in a number of practical applications where interfacial resistance between layers is frequently a major bottleneck to effective heat dissipation. For example, efficient heat transfer at silicon/aluminum and silicon/copper interfaces is very critical in power electronics packages used in hybrid electric vehicle applications. It is therefore important to understand the factors that govern and impact thermal transport at semiconductor/metal interfaces. Hence, in this study, we use classical molecular dynamics modeling to understand and study thermal transport in silicon and aluminum, and some preliminary modeling to study thermal transport at the interface between silicon and aluminum. A good match is shown between our modeling results for thermal conductivity in silicon and aluminum and the experimental data. The modeling results from this study also match well with relevant numerical studies in the literature for thermal conductivity. In addition, preliminary modeling results indicate that the interfacial thermal conductance for a perfect silicon/aluminum interface is of the same order as experimental data in the literature as well as diffuse mismatch model results accounting for realistic phonon dispersion curves.

scholarly journals Decoupling electron and phonon transport in single-nanowire hybrid materials for high-performance thermoelectrics

2021 ◽  
Vol 7 (20) ◽  
pp. eabe6000
Author(s):  
Lin Yang ◽  
Madeleine P. Gordon ◽  
Akanksha K. Menon ◽  
Alexandra Bruefach ◽  
Kyle Haas ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Electrical Transport ◽  
High Performance ◽  
Figure Of Merit ◽  
Phonon Transport ◽  
Core Shell ◽  
Nanowire Diameter ◽  
High Performing ◽  
Polycrystalline Thin Films

Organic-inorganic hybrids have recently emerged as a class of high-performing thermoelectric materials that are lightweight and mechanically flexible. However, the fundamental electrical and thermal transport in these materials has remained elusive due to the heterogeneity of bulk, polycrystalline, thin films reported thus far. Here, we systematically investigate a model hybrid comprising a single core/shell nanowire of Te-PEDOT:PSS. We show that as the nanowire diameter is reduced, the electrical conductivity increases and the thermal conductivity decreases, while the Seebeck coefficient remains nearly constant—this collectively results in a figure of merit, ZT, of 0.54 at 400 K. The origin of the decoupling of charge and heat transport lies in the fact that electrical transport occurs through the organic shell, while thermal transport is driven by the inorganic core. This study establishes design principles for high-performing thermoelectrics that leverage the unique interactions occurring at the interfaces of hybrid nanowires.

scholarly journals First-Principles-Based Interatomic Potential for SI and Its Thermal Conductivity

2011 ◽  
Author(s):  
Keivan Esfarjani ◽  
Gang Chen ◽  
Asegun Henry
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Properties ◽  
Force Field ◽  
Molecular Dynamics Simulations ◽  
First Principles ◽  
Density Functional ◽  
Interatomic Potential ◽  
Force Constants ◽  
Dynamics Simulations

Based on first-principles density-functional calculations, we have developed and tested a force-field for silicon, which can be used for molecular dynamics simulations and the calculation of its thermal properties. This force field uses the exact Taylor expansion of the total energy about the equilibrium positions up to 4th order. In this sense, it becomes systematically exact for small enough displacements, and can reproduce the thermodynamic properties of Si with high fidelity. Having the harmonic force constants, one can easily calculate the phonon spectrum of this system. The cubic force constants, on the other hand, will allow us to compute phonon lifetimes and scattering rates. Results on equilibrium Green-Kubo molecular dynamics simulations of thermal conductivity as well as an alternative calculation of the latter based on the relaxation-time approximation will be reported. The accuracy and ease of computation of the lattice thermal conductivity using these methods will be compared. This approach paves the way for the construction of accurate bulk interatomic potentials database, from which lattice dynamics and thermal properties can be calculated and used in larger scale simulation methods such as Monte Carlo.

scholarly journals Thermal Transport in Graphene Oxide Films: Theoretical Analysis and Molecular Dynamics Simulation

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 285 ◽  
Author(s):  
Yi Yang ◽  
Dan Zhong ◽  
Yilun Liu ◽  
Donghui Meng ◽  
Lina Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Graphene Oxide ◽  
Molecular Dynamics Simulation ◽  
Thermal Transport ◽  
Oxide Films ◽  
Vacancy Defect ◽  
Transport Processes ◽  
Dynamics Simulation ◽  
Great Promise

As a derivative material of graphene, graphene oxide films hold great promise in thermal management devices. Based on the theory of Fourier formula, we deduce the analytical formula of the thermal conductivity of graphene oxide films. The interlaminar thermal property of graphene oxide films is studied using molecular dynamics simulation. The effect of vacancy defect on the thermal conductance of the interface is considered. The interfacial heat transfer efficiency of graphene oxide films strengthens with the increasing ratio of the vacancy defect. Based on the theoretical model and simulation results, we put forward an optimization model of the graphene oxide film. The optimal structure has the minimum overlap length and the maximum thermal conductivity. An estimated optimal overlap length for the GO (graphene-oxide) films with degree of oxidation 10% and density of vacancy defect 2% is 0.33 μm. Our results can provide effective guidance to the rationally designed defective microstructures on engineering thermal transport processes.

scholarly journals Using a monomer potential energy surface to perform approximate path integral molecular dynamics simulation of ab initio water at near-zero added cost

2019 ◽  
Vol 21 (1) ◽  
pp. 409-417 ◽  
Author(s):  
Daniel C. Elton ◽  
Michelle Fritz ◽  
Marivi Fernández-Serra
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Molecular Dynamics Simulation ◽  
Potential Energy ◽  
Path Integral ◽  
Liquid Water ◽  
Density Functional ◽  
Energy Surface ◽  
Dynamics Simulation ◽  
Functional Theory

We present a new approximate method for doing path integral molecular dynamics simulation with density functional theory and show the utility of the method for liquid water.

Molecular Dynamics Simulation on the Out-of Plane Thermal Conductivity of Single-Crystal Carbon Thin Films

2009 ◽  
Vol 60-61 ◽  
pp. 430-434 ◽  
Author(s):  
Xing Li Zhang ◽  
Zhao Wei Sun ◽  
Guo Qiang Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Potential Energy ◽  
Film Thickness ◽  
Single Crystal ◽  
Diamond Crystal ◽  
Dynamics Simulation ◽  
Crystal Direction

In this article, we select corresponding Tersoff potential energy to build potential energy model and investigate the thermal conductivities of single-crystal carbon thin-film. The equilibrium molecular dynamics (EMD) method is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (001), and the non-equilibrium molecular dynamics (NEMD) is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (111). The results of calculations demonstrate that the nanometer thin film thermal conductivity of diamond crystal is remarkably lower than the corresponding bulk experimental data and increase with increasing the film thickness, and the nanometer thin film thermal conductivity of diamond crystal relates to film thickness linearly in the simulative range. The nanometer thin film thermal conductivity also demonstrates certain regularity with the change of temperature. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of nanometer thin films.

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