scholarly journals Erratum: Quantum mechanical prediction of four-phonon scattering rates and reduced thermal conductivity of solids [Phys. Rev. B 93 , 045202 (2016)]

2018 ◽  
Vol 97 (7) ◽  
Author(s):  
Tianli Feng ◽  
Xiulin Ruan
Keyword(s):  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Quantum Mechanical ◽  
Mechanical Prediction ◽  
Scattering Rates

scholarly journals Thermal Conductivity of BAs under Pressure

2021 ◽  
Author(s):  
Songrui Hou ◽  
Bo Sun ◽  
Fei Tian ◽  
Qingan Cai ◽  
Youming Xu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pressure Dependence ◽  
Acoustic Phonon ◽  
Density Functional ◽  
Phonon Scattering ◽  
Ambient Pressure ◽  
Functional Theory ◽  
Small Phase ◽  
Diamond Anvil ◽  
Scattering Rates

Abstract Boron arsenide (BAs) is an ultrahigh-thermal-conductivity material with special phonon-phonon scattering behaviors. At ambient pressure, the bunching of acoustic phonon branches in BAs is believed to result in a small phase space for three-phonon scattering. Density functional theory predicts that this acoustic phonon bunching effect is sensitive to pressure and leads to an unusual pressure dependence of thermal conductivity. To explore this physics, we measure the thermal conductivity of BAs from 0 to 25 GPa using time-domain thermoreflectance in a diamond anvil cell. We characterized two BAs samples with ambient thermal conductivities of 350 and 480 W m-1 K-1. Our experiments show that the thermal conductivity of both samples depends weakly on pressure from 0 to 25 GPa. We attribute the weak pressure dependence of the thermal conductivity of BAs to the weak pressure dependence of total phonon-phonon scattering rates. Our experimental results are consistent with DFT predictions that three-phonon scattering rates increase from 0 to 25 GPa, while four-phonon scattering rates decrease.

Comparison of Scattering Rates and Thermal Conductivity in Diamond Using Dispersion Curve Data

2005 ◽  
Author(s):  
Todd Kalisik ◽  
Pradip Majumdar ◽  
John Shafer
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Vibrational Energy ◽  
Phonon Dispersion ◽  
Symmetry Direction ◽  
Curve Fit ◽  
Polynomial Curve ◽  
Dispersion Data ◽  
Scattering Rates

The understanding of the mechanism of thermal energy transfer in thin films ranging in thicknesses from micro-scale to nano-scale is becoming very important. Thin films must be modeled at the atomic level and this entails treating the heat transfer as vibrations in a crystal lattice. The concept of phonons can be used to model the vibrational energy of the crystal. Phonon scattering rates and thermal conductivity are investigated for Cubic C (diamond). Boundary scattering, Umklapp processes, and Normal processes are the mechanisms considered for heat flow resistance. The normal processes are included due to there indirect effect on resistance (through phonon redistribution). Three symmetry directions [001], [110], [111], and three polarizations for each direction in the first Brillouin zone are considered. The main purpose of the paper is to study the effect of the curvature of the phonon dispersion curves when computing the phonon scattering rates and thermal conductivity. A comparison of thermal conductivity for each polarization and symmetry direction is made between a continuum model, a linear curve fit and a polynomial curve fit of dispersion data. A comparison is also made between the scattering rates for each polarization, symmetry direction as well as the group velocity for each.

Mode-Decay Molecular Dynamics for Frequency-Dependent Phonon Scattering Rates

2014 ◽  
Author(s):  
M. D. Gerboth ◽  
D. G. Walker
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Standing Wave ◽  
Phonon Scattering ◽  
Relaxation Rates ◽  
Phonon Modes ◽  
Crystalline Materials ◽  
Transmission Coefficients ◽  
Energy Dependent ◽  
Scattering Rates

The thermal conductivity of crystalline materials can be determined in a statistical mechanical framework as long as phonon relaxation rates are known. Unfortunately, these quantities are difficult if not impossible to measure directly, and attempts to deduce these quantities yield gross averages not energy dependent relationships. Consequently, researchers often rely on heuristic models such as Holland’s suite of scattering rates for various phonon modes. A new molecular dynamics method was developed to estimate mode-dependent scattering rates by tracking the decay of an initially imposed standing wave. The wave vector is systematically changed and the corresponding decay is collected. Ultimately, the the thermal conductivity can be reconstructed using a Landauer formalism. The phonon scattering rates of a LJ crystal are calculated using this method. The standing wave decay approach allows scattering rates to be probed more directly than wave packet simulations, which are often used to obtain transmission coefficients.

scholarly journals FourPhonon: An extension module to ShengBTE for computing four-phonon scattering rates and thermal conductivity

2022 ◽  
Vol 270 ◽  
pp. 108179
Author(s):  
Zherui Han ◽  
Xiaolong Yang ◽  
Wu Li ◽  
Tianli Feng ◽  
Xiulin Ruan
Keyword(s):  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Scattering Rates

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 Scattering Mechanisms and Suppression of Bipolar Diffusion Effect in Bi2Te2.85Se0.15Ix Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1564
Author(s):  
Jin Hee Kim ◽  
Song Yi Back ◽  
Jae Hyun Yun ◽  
Ho Seong Lee ◽  
Jong-Soo Rhyee
Keyword(s):  
Thermal Conductivity ◽  
Carrier Concentration ◽  
Hall Mobility ◽  
Lattice Distortion ◽  
Phonon Scattering ◽  
Iodine Concentration ◽  
Mean Free Path ◽  
Bandgap Energy ◽  
Diffusion Effect ◽  
Iodine Doping

We investigated the anisotropic thermoelectric properties of the Bi2Te2.85Se0.15Ix (x = 0.0, 0.1, 0.3, 0.5 mol.%) compounds, synthesized by ball-milling and hot-press sintering. The electrical conductivities of the Bi2Te2.85Se0.15Ix were significantly improved by the increase of carrier concentration. The dominant electronic scattering mechanism was changed from the mixed (T ≤ 400 K) and ionization scattering (T ≥ 420 K) for pristine compound (x = 0.0) to the acoustic phonon scattering by the iodine doping. The Hall mobility was also enhanced with the increasing carrier concentration. The enhancement of Hall mobility was caused by the increase of the mean free path of the carrier from 10.8 to 17.7 nm by iodine doping, which was attributed to the reduction of point defects without the meaningful change of bandgap energy. From the electron diffraction patterns, a lattice distortion was observed in the iodine doped compounds. The modulation vector due to lattice distortion increased with increasing iodine concentration, indicating the shorter range lattice distortion in real space for the higher iodine concentration. The bipolar thermal conductivity was suppressed, and the effective masses were increased by iodine doping. It suggests that the iodine doping minimizes the ionization scattering giving rise to the suppression of the bipolar diffusion effect, due to the prohibition of the BiTe1 antisite defect, and induces the lattice distortion which decreases lattice thermal conductivity, resulting in the enhancement of thermoelectric performance.

scholarly journals First-principles predictions of low lattice thermal conductivity and high thermoelectric performance of AZnSb (A = Rb, Cs)

RSC Advances ◽  
2021 ◽  
Vol 11 (25) ◽  
pp. 15486-15496
Author(s):  
Enamul Haque
Keyword(s):  
Thermal Conductivity ◽  
Debye Temperature ◽  
Layered Structure ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Thermoelectric Performance

The layered structure, and presence of heavier elements Rb/Cs and Sb induce high anharmonicity, low Debye temperature, intense phonon scattering, and hence, low lattice thermal conductivity.

Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

2019 ◽  
Vol 34 (02) ◽  
pp. 2050019 ◽  
Author(s):  
Y. Zhang ◽  
M. M. Fan ◽  
C. C. Ruan ◽  
Y. W. Zhang ◽  
X.-J. Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Sintered Sample ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
The Third ◽  
Ceramic Samples ◽  
Optimum Formula

[Formula: see text] ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit [Formula: see text] of [Formula: see text]. The optimum [Formula: see text] value of 0.26 is achieved at 923 K by the third sintered sample.

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