Influence of structure disorder on the lattice thermal conductivity of polycrystals: A frequency-dependent phonon-transport study

2012 ◽  
Vol 111 (1) ◽  
pp. 014309 ◽  
Author(s):  
Qing Hao
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Frequency Dependent ◽  
Transport Study ◽  
Structure Disorder

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 .

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.

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.

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.

scholarly journals Phonon Transport and Thermoelectric Properties of Imidazole-Graphyne

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5604
Author(s):  
Yanyan Chen ◽  
Jie Sun ◽  
Wei Kang ◽  
Qian Wang
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Transport Theory ◽  
Hole Concentration ◽  
Chemical Properties ◽  
Phonon Transport ◽  
Thermoelectric Performance ◽  
Boltzmann Transport ◽  
Boltzmann Transport Theory ◽  
Carbon Based

The pentagon has been proven to be an important structural unit for carbon materials, leading to different physical and chemical properties from those of hexagon-based allotropes. Following the development from graphene to penta-graphene, a breakthrough has very recently been made for graphyne—for example, imidazole-graphyne (ID-GY) was formed by assembling experimentally synthesized pentagonal imidazole molecules and acetylenic linkers. In this work, we study the thermal properties and thermoelectric performance of ID-GY by combining first principle calculations with the Boltzmann transport theory. The calculated lattice thermal conductivity of ID-GY is 10.76 W/mK at 300 K, which is only one tenth of that of γ-graphyne (106.24 W/mK). A detailed analysis of the harmonic and anharmonic properties, including the phonon group velocity, phonon lifetime, atomic displacement parameter, and bond energy curves, reveals that the low lattice thermal conductivity can be attributed to the low Young’s modulus, low Debye temperature, and high Grüneisen parameter. Furthermore, at room temperature, ID-GY can reach a high ZT value of 0.46 with a 5.8 × 1012 cm−2 hole concentration, which is much higher than the value for many other carbon-based materials. This work demonstrates that changing structural units from hexagonal to pentagonal can significantly reduce the lattice thermal conductivity and enhance the thermoelectric performance of carbon-based materials.

The Effects of Diameter and Chirality in the Thermal Transport in Free-Standing and Supported Carbon-Nanotubes

2012 ◽  
Author(s):  
Bo Qiu ◽  
Yan Wang ◽  
Qing Zhao ◽  
Xiulin Ruan
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Thermal Transport ◽  
Lattice Thermal Conductivity ◽  
Axial Direction ◽  
Md Simulations ◽  
Phonon Transport ◽  
Free Standing ◽  
Effective Boundary ◽  
Phonon Lifetime

We use molecular dynamics (MD) simulations to explore the lattice thermal transport in freestanding and supported single-wall carbon-nanotube (SWCNT) in comparison to that in graphene nanoribbon (GNR) and graphene sheet. We find the lattice thermal conductivity of freestanding SWCNT and GNR increases with diameter/width and approaches that of graphene. This is partly attributed to the curvature that shortens phonon lifetime in SWCNT. In contrast to GNR, there is only weak chirality dependence in the thermal conductivity of freestanding SWCNT. When SWCNT is put on substrate, an effective boundary along the SWCNT axial direction at the SWCNT-substrate interface is created, rendering resemblance between the phonon transport in supported SWCNT and that in freestanding GNR. As a result, the thermal conductivity of supported SWCNTs differ by around 10%, depending on chirality. The thermal conductivity of SWCNT decreases by about 34–41% when supported, which is less than that of the reduction seen in supported graphene.

Phonon transport and thermoelectric properties of semiconducting Bi2Te2X (X = S, Se, Te) monolayers

2019 ◽  
Vol 21 (10) ◽  
pp. 5679-5688 ◽  
Author(s):  
Zahid Rashid ◽  
Arun S. Nissimagoudar ◽  
Wu Li
Keyword(s):  
Thermal Conductivity ◽  
Dimensionality Reduction ◽  
Thermoelectric Properties ◽  
Lattice Thermal Conductivity ◽  
Phonon Transport ◽  
Thermoelectric Conversion ◽  
Conversion Performance ◽  
Novel Strategy

Confinement or dimensionality reduction is a novel strategy to reduce the lattice thermal conductivity and, consequently, to improve the thermoelectric conversion performance.

scholarly journals Pivotal role of magnetic ordering and strain in lattice thermal conductivity of chromium-trihalide monolayers

2D Materials ◽  
2021 ◽  
Author(s):  
Tribhuwan Pandey ◽  
Francois M Peeters ◽  
Milorad V Milosevic
Keyword(s):  
Thermal Conductivity ◽  
Magnetic Materials ◽  
Tensile Strain ◽  
Lattice Thermal Conductivity ◽  
Magnetic Ordering ◽  
Phonon Transport ◽  
Phonon Coupling ◽  
Spin Devices ◽  
Very High

Abstract Understanding the coupling between spin and phonons is critical for controlling the lattice thermal conductivity (κl) in magnetic materials, as we demonstrate here for CrX3 (X = Br and I) monolayers. We show that these compounds exhibit large spin-phonon coupling (SPC), dominated by out-ofplane vibrations of Cr atoms, resulting in significantly different phonon dispersions in ferromagnetic (FM) and paramagnetic (PM) phases. Lattice thermal conductivity calculations provide additional evidence for strong SPC, where particularly large κlis found for the FM phase. Most strikingly, PM and FM phases exhibit radically different behavior with tensile strain, where κl increases with strain for the PM phase, and strongly decreases for the FM phase — as we explain through analysis of phonon lifetimes and scattering rates. Taken all together, we uncover the very high significance of SPC on the phonon transport in CrX3 monolayers, a result extendable to other 2D magnetic materials, that will be useful in further design of thermal spin devices.

scholarly journals Rationalizing phonon dispersion for lattice thermal conductivity of solids

2018 ◽  
Vol 5 (6) ◽  
pp. 888-894 ◽  
Author(s):  
Zhiwei Chen ◽  
Xinyue Zhang ◽  
Siqi Lin ◽  
Lidong Chen ◽  
Yanzhong Pei
Keyword(s):  
Thermal Conductivity ◽  
Boundary Condition ◽  
Periodic Boundary Condition ◽  
Periodic Boundary ◽  
Lattice Thermal Conductivity ◽  
Phonon Dispersion ◽  
Phonon Transport ◽  
Past Century ◽  
Energy Applications ◽  
Fundamental Properties

Abstract Lattice thermal conductivity (κL) is one of the most fundamental properties of solids. The acoustic–elastic-wave assumption, proposed by Debye (Debye P. Ann Phys 1912; 344: 789–839), has led to linear phonon dispersion being the most common approximation for understanding phonon transport over the past century. Such an assumption does not take into account the effect of a periodic boundary condition on the phonon dispersion, originating from the nature of periodicity on atomic arrangements. Driven by modern demands on the thermal functionality of materials, with κL ranging from ultra-low to ultra-high, any deviation from the Debye approximation in real materials becomes more and more significant. This work takes into account the periodic boundary condition, and therefore rationalizes the phonon dispersion to be more realistic. This significantly improves the precision for quickly predicting κL without any fitting parameters, as demonstrated in hundreds of materials, and offers a theoretical basis rationalizing κL to be lower than the minimum currently accepted based on the Debye dispersion. This work paves the way for designing solids with expected κL and particularly inspires the advancement of low-κL materials for thermal energy applications.

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