Thermal conductivity of chalcogenide glass phases governed by disparity in phonon group velocity

“Umklapp collisions and thermal conductivity” deals with heat conduction in a dielectric solid. Collisions of phonons are divided into Umklapp and normal according as a reciprocal lattice vector is or is not involved in the phonon momentum balance. A local temperature is defined by appeal to local thermodynamic equilibrium. An equilibrium phonon distribution can be off-centred, yet non-decaying, if the only collisions are “normal”, conserving the total phonon momentum. Then heat flow does not decay, even if a representative collision reverses the phonon group velocity. Conversely, in an Umklapp collision it is the non-conservation of phonon momentum that causes heat flow to decay.

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THE EFFECT OF SPONTANEOUS AND PIEZOELECTRIC POLARIZATION ON THERMAL CONDUCTIVITY OF InN

International Journal of Modern Physics B ◽

10.1142/s0217979213500318 ◽

2013 ◽

Vol 27 (09) ◽

pp. 1350031 ◽

Cited By ~ 3

Author(s):

BIJAYA KUMAR SAHOO ◽

SUSANT KUMAR SAHOO ◽

SUKDEV SAHOO

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Group Velocity ◽

Room Temperature ◽

Phonon Scattering ◽

Polarization Property ◽

Optical And Electrical Properties ◽

High Quality ◽

Phonon Group Velocity ◽

Debye Frequency

The spontaneous (SP) and piezoelectric (PZ) polarization present in the wurtzite III nitrides influence the optical and electrical properties of these materials. The effects of SP and PZ polarization on thermal properties of III nitrides have yet to be investigated. Here we have investigated the SP and PZ effects on thermal conductivity of InN . Inclusion of polarization property modifies the group velocity of phonons. The combined phonon scattering rates and thermal conductivity k of InN are calculated using modified phonon group velocity, Debye frequency and Debye temperature. Without SP and PZ polarization, the room temperature thermal conductivity of InN is found to be 132.55 W/m.K. Inclusion of SP and PZ polarization property enhances the room temperature thermal conductivity from 132.55 to 134.32 W/m.K. Our predicted thermal conductivity values are closer to the recent experimental value 120 W/m.K measured by Levander et al. for a high quality irradiated InN films at room temperature.

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Lattice Dynamics Study of Anisotropic Heat Conduction in Superlattices

MRS Proceedings ◽

10.1557/proc-626-z8.3 ◽

2000 ◽

Vol 626 ◽

Author(s):

B. Yang ◽

G. Chen

Keyword(s):

Thermal Conductivity ◽

Group Velocity ◽

Lattice Dynamics ◽

Phonon Scattering ◽

Diffuse Interface ◽

Phonon Confinement ◽

Dynamics Model ◽

Phonon Group Velocity ◽

Anisotropic Heat Conduction ◽

The Cross

ABSTRACTPast studies on the thermal conductivity suggest that phonon confinement and the associated group velocity reduction are the causes of the observed drop in the cross-plane thermal conductivity of semiconductor superlattices. In this work, we investigate the contribution of phonon confinement to the in-plane thermal conductivity of superlattices and the anisotropic effects of phonon confinement on the thermal conductivity in different directions, using a lattice dynamics model. We find that the reduced phonon group velocity due to phonon confinement may account for the dramatic reduction in the cross-plane thermal conductivity, but the in-plane thermal conductivity drop, caused by the reduced group velocity, is much less than the reported experimental results. This suggests that the reduced relaxation time due to diffuse interface phonon scattering, dislocation scattering, etc, should make major contribution to the in-plane thermal conductivity reduction.

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Lattice thermal conductivity in isotope diamond asymmetric superlattices

Japanese Journal of Applied Physics ◽

10.35848/1347-4065/ac4304 ◽

2021 ◽

Author(s):

Hsu Kai Weng ◽

Akira NAGAKUBO ◽

Hideyuki Watanabe ◽

Hirotsugu OGI

Keyword(s):

Thermal Conductivity ◽

Specific Heat ◽

Group Velocity ◽

Lattice Thermal Conductivity ◽

Trade Off ◽

Number Of Layers ◽

Phonon Group Velocity ◽

Wide Range ◽

Superlattice Structures ◽

Superlattice Period

Abstract We study lattice thermal conductivity of isotope diamond superlattices consisting of 12C and 13C diamond layers at various superlattice periods. It is found that the thermal conductivity of a superlattice is significantly deduced from that of pure diamond because of the reduction of the phonon group velocity near the folded Brillouin zone. The results show that asymmetric superlattices with different number of layers of 12C and 13C diamonds exhibit higher thermal conductivity than symmetric superlattices even with the same superlattice period, and we find that this can be explained by the trade-off between the effects of phonon specific heat and phonon group velocity. Furthermore, impurities and imperfect superlattice structures are also found to significantly reduce the thermal conductivity, suggesting that these effects can be exploited to control the thermal conductivity over a wide range.

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Heat transport through propagon-phonon interaction in epitaxial amorphous-crystalline multilayers

Communications Physics ◽

10.1038/s42005-021-00653-w ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Takafumi Ishibe ◽

Ryo Okuhata ◽

Tatsuya Kaneko ◽

Masato Yoshiya ◽

Seisuke Nakashima ◽

...

Keyword(s):

Group Velocity ◽

Density Of States ◽

Heat Dissipation ◽

Lattice Mismatch ◽

Lead Telluride ◽

Amorphous Layer ◽

Interface Layer ◽

Phonon Transport ◽

Nanoscale Systems ◽

Phonon Group Velocity

AbstractManaging heat dissipation is a necessity for nanoscale electronic devices with high-density interfaces, but despite considerable effort, it has been difficult to establish the phonon transport physics at the interface due to a “complex” interface layer. In contrast, the amorphous/epitaxial interface is expected to have almost no “complex” interface layer due to the lack of lattice mismatch strain and less associated defects. Here, we experimentally observe the extremely-small interface thermal resistance per unit area at the interface of the amorphous-germanium sulfide/epitaxial-lead telluride superlattice (~0.8 ± 4.0 × 10‒9 m2KW−1). Ab initio lattice dynamics calculations demonstrate that high phonon transmission through this interface can be predicted, like electron transport physics, from large vibron-phonon density-of-states overlapping and phonon group velocity similarity between propagon in amorphous layer and “conventional” phonon in crystal. This indicates that controlling phonon (or vibron) density-of-states and phonon group velocity similarity can be a comprehensive guideline to manage heat conduction in nanoscale systems.

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

Physical Chemistry Chemical Physics ◽

10.1039/c7cp06065c ◽

2017 ◽

Vol 19 (47) ◽

pp. 32072-32078 ◽

Cited By ~ 30

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.

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Intensity-dependent phonon group velocity in SiO2 glasses at 0.023 K

Physics Letters A ◽

10.1016/0375-9601(76)90137-7 ◽

1976 ◽

Vol 57 (5) ◽

pp. 487-488 ◽

Cited By ~ 1

Author(s):

J.E. Graebner ◽

B. Golding

Keyword(s):

Group Velocity ◽

Phonon Group Velocity

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Phonon group velocity and thermal conduction in superlattices

Physical Review B ◽

10.1103/physrevb.60.2627 ◽

1999 ◽

Vol 60 (4) ◽

pp. 2627-2630 ◽

Cited By ~ 180

Author(s):

Shin-ichiro Tamura ◽

Yukihiro Tanaka ◽

Humphrey J. Maris

Keyword(s):

Group Velocity ◽

Thermal Conduction ◽

Phonon Group Velocity

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Tuning thermal conductivity of crystalline polymer nanofibers by interchain hydrogen bonding

RSC Advances ◽

10.1039/c5ra18519j ◽

2015 ◽

Vol 5 (107) ◽

pp. 87981-87986 ◽

Cited By ~ 23

Author(s):

Lin Zhang ◽

Morgan Ruesch ◽

Xiaoliang Zhang ◽

Zhitong Bai ◽

Ling Liu

Keyword(s):

Thermal Conductivity ◽

Hydrogen Bonding ◽

Hydrogen Bonds ◽

Group Velocity ◽

Thermal Conduction ◽

Crystalline Polymer ◽

Polymer Chains ◽

Torsional Motion ◽

Polymer Nanofibers

Interchain hydrogen bonds enhance thermal conduction in crystalline polymer nanofibers by confining torsional motion of polymer chains and by increasing the group velocity of phonons.

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A C20-based 3D carbon allotrope with high thermal conductivity

Physical Chemistry Chemical Physics ◽

10.1039/c9cp02202c ◽

2020 ◽

Vol 22 (1) ◽

pp. 306-312 ◽

Cited By ~ 2

Author(s):

Yupeng Shen ◽

Fancy Qian Wang ◽

Jie Liu ◽

Qian Wang

Keyword(s):

Thermal Conductivity ◽

Group Velocity ◽

Structural Unit ◽

High Thermal Conductivity ◽

Carbon Allotrope ◽

Large Group

A new 3D carbon allotrope composed of C20 as its structural unit is proposed, which is stable and possesses high thermal conductivity due to the weak anharmonicity and large group velocity of phonons in this structure.

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