scholarly journals Thermoelectric Properties of Hexagonal M2C3 (M = As, Sb, and Bi) Monolayers from First-Principles Calculations

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 597 ◽  
Author(s):  
Xue-Liang Zhu ◽  
Peng-Fei Liu ◽  
Guofeng Xie ◽  
Wu-Xing Zhou ◽  
Bao-Tian Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Density Functional ◽  
Optical Absorption Coefficient ◽  
Boltzmann Transport ◽  
Low Thermal Conductivity ◽  
Phonon Group Velocity ◽  
Optical Modes ◽  
Potential Applications ◽  
High Seebeck Coefficient ◽  
Phonon Relaxation Time

Hexagonal M2C3 compound is a new predicted functional material with desirable band gaps, a large optical absorption coefficient, and ultrahigh carrier mobility, implying its potential applications in photoelectricity and thermoelectric (TE) devices. Based on density-functional theory and Boltzmann transport equation, we systematically research the TE properties of M2C3. Results indicate that the Bi2C3 possesses low phonon group velocity (~2.07 km/s), low optical modes (~2.12 THz), large Grüneisen parameters (~4.46), and short phonon relaxation time. Based on these intrinsic properties, heat transport ability will be immensely restrained and therefore lead to a low thermal conductivity (~4.31 W/mK) for the Bi2C3 at 300 K. A twofold degeneracy is observed at conduction bands along Γ-M direction, which gives a high n-type electrical conductivity. Its low thermal conductivity and high Seebeck coefficient lead to an excellent TE response. The maximum thermoelectric figure of merit (ZT) of n-type can approach 1.41 for Bi2C3. This work shows a perspective for applications of TE and stimulate further experimental synthesis.

scholarly journals Electron, phonon and thermoelectric properties of Cu7PS6 crystal calculated at DFT level

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
B. Andriyevsky ◽  
I. E. Barchiy ◽  
I. P. Studenyak ◽  
A. I. Kashuba ◽  
M. Piasecki
Keyword(s):  
Thermal Conductivity ◽  
Effective Mass ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Copper Ions ◽  
Boltzmann Transport ◽  
Phonon Modes ◽  
Electron Effective Mass ◽  
Low Thermal Conductivity ◽  
Ion Conducting

AbstractThe promising class of the environment-friendly thermoelectrics is the copper-based argyrodite-type ion-conducting crystals exhibiting just extraordinary low thermal conductivity below the glass limit associated with the molten copper sublattice leading to a softening of phonon modes. To explain why the argyrodite structure containing copper ions favors the low thermal conductivity, we have utilized the ab initio calculations of the electron, phonon, and thermoelectric properties of Cu7PS6 crystal in the framework of the density functional and Boltzmann transport theories. To obtain the reliable thermoelectric properties of Cu7PS6, we take into account the dependence of the electron effective mass m* on the redundant carrier concentration n. We propose to use the Burstein–Moss effect for the calculation of the electron effective mass m* of a semiconductor. We have found the strong nonlinear character of copper atom vibrations in Cu7PS6 which exceeds substantially the similar values for phosphorous and sulfur atoms. The large vibration nonlinearity of the copper atoms found in Cu7PS6 explains the diffusion-like heat transfer and the relatively low coefficient of the lattice thermal conductivity (κ = 0.7 W/(m K)), which is favorable to achieve the large thermoelectric figure of merit.

scholarly journals Diffusive nature of thermal transport in stanene

2016 ◽  
Vol 18 (21) ◽  
pp. 14257-14263 ◽  
Author(s):  
Arun S. Nissimagoudar ◽  
Aaditya Manjanath ◽  
Abhishek K. Singh
Keyword(s):  
Thermal Conductivity ◽  
Density Functional Theory ◽  
Thermal Transport ◽  
Density Functional ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
Low Thermal Conductivity

Using the phonon Boltzmann transport formalism and density functional theory based calculations, we show that stanene has a low thermal conductivity.

scholarly journals Electron, Phonon and Thermoelectric Properties of Cu7PS6 Crystal Calculated at DFT Level

2021 ◽  
Author(s):  
Bohdan Andriyevskyy ◽  
Igor Barchiy ◽  
Ihor Studenyak ◽  
Andriy Kashuba ◽  
Michał Piasecki
Keyword(s):  
Thermal Conductivity ◽  
Effective Mass ◽  
Thermoelectric Properties ◽  
Density Functional ◽  
Copper Ions ◽  
Boltzmann Transport ◽  
Phonon Modes ◽  
Electron Effective Mass ◽  
Low Thermal Conductivity ◽  
Ion Conducting

Abstract The promising class of the environment-friendly thermoelectrics is the copper-based argyrodite-type ion-conducting crystals exhibiting just extraordinary low thermal conductivity below the glass limit associated with the molten copper sublattice leading to a softening of phonon modes. To explain why the argyrodite structure containing copper ions favors the low thermal conductivity, we have utilized the ab initio calculations of the electron, phonon, and thermoelectric properties of Cu7PS6 crystal in the framework of the density functional and Boltzmann transport theories. To obtain the reliable thermoelectric properties of Cu7PS6, we take into account the dependence of the electron effective mass m* on the redundant carrier concentration n. We propose to use the Burstein-Moss effect for the calculation of the electron effective mass m* of a semiconductor. We have found the strong nonlinear character of copper atom vibrations in Cu7PS6 which exceeds substantially the similar values for phosphorous and sulfur atoms. The large vibration nonlinearity of the copper atoms found in Cu7PS6 explains the diffusion-like heat transfer and the relatively low coefficient of the lattice thermal conductivity (κ = 0.7 W/(m⋅K)), which is favorable to achieve the large thermoelectric figure of merit.

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 Ultralow and anisotropic thermal conductivity in semiconductor As2Se3

2018 ◽  
Vol 20 (3) ◽  
pp. 1809-1816 ◽  
Author(s):  
Robert L. González-Romero ◽  
Alex Antonelli ◽  
Anderson S. Chaves ◽  
Juan J. Meléndez
Keyword(s):  
Thermal Conductivity ◽  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Boltzmann Transport Equation ◽  
First Principles Calculations ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
Anisotropic Thermal Conductivity

An ultralow lattice thermal conductivity of 0.14 W m−1 K−1 along the b⃑ axis of As2Se3 single crystals was obtained at 300 K by first-principles calculations involving density functional theory and the resolution of the Boltzmann transport equation.

A Study of Spatially-Resolved Non-Equilibrium in Laser-Irradiated Graphene Using Boltzmann Transport Equation

2013 ◽  
Author(s):  
Ajit K. Vallabhaneni ◽  
James Loy ◽  
Dhruv Singh ◽  
Xiulin Ruan ◽  
Jayathi Murthy
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Laser Irradiation ◽  
Density Functional ◽  
Boltzmann Transport ◽  
Energy Carriers ◽  
Spatially Resolved ◽  
Scattering Rate ◽  
Phonon Generation ◽  
Non Equilibrium

Raman spectroscopy is typically used to characterize graphene in experiments and also to measure properties like thermal conductivity and optical phonon lifetime. The laser-irradiation processes underlying this measurement technique include coupling between photons, electrons and phonons. Recent experimental studies have shown that e-ph scattering limits the performance of graphene-based electronic devices due to the difference in their timescales of relaxation resulting in various bottleneck effects. Furthermore, recently published thermal conductivity measurements on graphene are sensitive to the laser spot size which strengthens the possibility of non-equilibrium between various phonon groups. These studies point to the need to study the spatially-resolved non-equilibrium between various energy carriers in graphene. In this work, we demonstrate non-equilibrium in the e-ph interactions in graphene by solving the linearized electron and phonon Boltzmann transport equations (BTE) iteratively under steady state conditions. We start by assuming that all the electrons equilibrate rapidly to an elevated temperature under laser-irradiation and they gradually relax by phonon emission and reach a steady state. The electron and phonon BTEs are coupled because the e-ph scattering rate depends on the phonon population while the rate of phonon generation depends on the e-ph scattering rate. We used density-functional theory/density-functional perturbation theory (DFT/DFPT) to calculate the electronic eigen states, phonon frequencies and the e-ph coupling matrix elements. We calculated the rate of energy loss from the hot electrons in terms of the phonon generation rate (PGR) which serve as an input for solving the BTE. Likewise, ph-ph relaxation times are calculated from the anharmonic lattice dynamics (LD)/FGR. Through our work, we obtained the spatially resolved temperature profiles of all the relevant energy carriers throughout the entire domain; these are impossible to obtain through experiments.

Strain engineering of phonon thermal transport properties in monolayer 2H-MoTe2

2017 ◽  
Vol 19 (47) ◽  
pp. 32072-32078 ◽  
Author(s):  
Aamir Shafique ◽  
Young-Han Shin
Keyword(s):  
Thermal Conductivity ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Boltzmann Transport Equation ◽  
Strain Engineering ◽  
First Principles Calculations ◽  
Boltzmann Transport ◽  
Phonon Group Velocity ◽  
Phonon Lifetime ◽  
Phonon Properties

The effect of strain on the phonon properties such as phonon group velocity, phonon anharmonicity, phonon lifetime, and lattice thermal conductivity of monolayer 2H-MoTe2is studied by solving the Boltzmann transport equation based on first principles calculations.

Thermoelectric performance of XI2 (X = Ge, Sn, Pb) bilayers

2021 ◽  
Author(s):  
Nan Lu ◽  
Jie Guan
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Transport Theory ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
Boltzmann Transport Theory ◽  
Dimensionless Figure Of Merit ◽  
Structure Calculations

Abstract We study the thermal and electronic transport properties as well as the TE performance of three two-dimensional XI2 (X = Ge, Sn, Pb) bilayers using density functional theory and Boltzmann transport theory. We compared the lattice thermal conductivity, electrical conductivity, Seebeck coefficient, and dimensionless figure of merit (ZT) for the XI2 monolayers and bilayers. Our results show that the lattice thermal conductivity at room temperature for the bilayers is as low as ~1.1-1.7 Wm-1K-1, which is about 1.6 times as large as the monolayers for all the three materials. Electronic structure calculations show that all the XI2 bilayers are indirect-gap semiconductors with the band gap values between 1.84 eV and 1.96 eV at PBE level, which is similar as the corresponding monolayers. The calculated results of ZT show that the bilayer structures display much less direction dependent TE efficiency and have much larger n-type ZT values compared with the monolayers. The dramatic difference between the monolayer and bilayer indicates that the inter-layer interaction plays an important role in the TE performance of XI2, which provides the tunability on their TE characteristics.

scholarly journals Effects of Al substitution by Si in Ti3AlC2 nanolaminate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. A. Hadi ◽  
Md Roknuzzaman ◽  
M. T. Nasir ◽  
U. Monira ◽  
S. H. Naqib ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid Solutions ◽  
Density Functional ◽  
Visible Region ◽  
Coating Materials ◽  
Cell Parameters ◽  
Barrier Coating ◽  
Cauchy Pressure ◽  
Potential Applications ◽  
Temperature Lattice

AbstractRecently, a series of high-purity Ti3(Al1−xSix)C2 solid solutions with new compositions (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) have been reported with interesting mechanical properties. Here, we have employed density functional theory for Ti3(Al1−xSix)C2 solid solutions to calculate a wider range of physical properties including structural, electronic, mechanical, thermal and optical. With the increase of x, a decrease of cell parameters is observed. All elastic constants and moduli increase with x. The Fermi level gradually increases, moving towards and past the upper bound of the pseudogap, when the value of x goes from zero to unity, indicating that the structural stability reduces gradually when the amount of Si increases within the Ti3(Al1−xSix)C2 system. In view of Cauchy pressure, Pugh’s ratio and Poisson’s ratio all compositions of Ti3(Al1−xSix)C2 are brittle in nature. Comparatively, low Debye temperature, lattice thermal conductivity and minimum thermal conductivity of Ti3AlC2 favor it to be a thermal barrier coating material. High melting temperatures implies that the solid solutions Ti3(Al1−xSix)C2 may have potential applications in harsh environments. In the visible region (1.8–3.1 eV), the minimum reflectivity of all compositions for both polarizations is above 45%, which makes them potential coating materials for solar heating reduction.

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