scholarly journals Tuning thermal transport in Si nanowires by isotope engineering

2016 ◽  
Vol 18 (37) ◽  
pp. 26262-26267 ◽  
Author(s):  
Miquel Royo ◽  
Riccardo Rurali
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Thermal Transport ◽  
Si Nanowires

The thermal conductivity of 28Six30Si1−x nanowires is reduced up to ∼20% (∼50%) at room (low) temperature with respect to isotope purfied nanowires.

scholarly journals Phonons and Thermal Transport in Si/SiO2 Multishell Nanotubes: Atomistic Study

2021 ◽  
Vol 11 (8) ◽  
pp. 3419
Author(s):  
Calina Isacova ◽  
Alexandr Cocemasov ◽  
Denis L. Nika ◽  
Vladimir M. Fomin
Keyword(s):  
Thermal Conductivity ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Geometrical Parameters ◽  
Boltzmann Transport ◽  
Si Nanowires ◽  
Relaxation Time Approximation ◽  
Atomistic Lattice ◽  
Key Factor ◽  
Atomistic Study

Thermal transport in the Si/SiO2 multishell nanotubes is investigated theoretically. The phonon energy spectra are obtained using the atomistic lattice dynamics approach. Thermal conductivity is calculated using the Boltzmann transport equation within the relaxation time approximation. Redistribution of the vibrational spectra in multishell nanotubes leads to a decrease of the phonon group velocity and the thermal conductivity as compared to homogeneous Si nanowires. Phonon scattering on the Si/SiO2 interfaces is another key factor of strong reduction of the thermal conductivity in these structures (down to 0.2 Wm−1K−1 at room temperature). We demonstrate that phonon thermal transport in Si/SiO2 nanotubes can be efficiently suppressed by a proper choice of nanotube geometrical parameters: lateral cross section, thickness and number of shells. We argue that such nanotubes have prospective applications in modern electronics, in cases when low heat conduction is required.

Atomistic Simulations of Heat Transport in Carbon Nanotubes Effected by Temperature and Stretch Strain

2011 ◽  
Vol 320 ◽  
pp. 38-44 ◽  
Author(s):  
Qing Yuan Meng ◽  
Yu Fei Gao ◽  
Xian Qin
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Low Temperature ◽  
Transport Properties ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Quantum Effect ◽  
Axial Strain ◽  
Thermal Transport Properties ◽  
Dynamic Structures

Carbon nanotubes (CNTs) is a well thermal transport nano materials, however, the thermal conductivity of CNTs has not been well established, only a few groups had reported experimental data and the existed simulation results ranged widely. Specially, the conclusions in low temperature section and dynamic structures were not very clearly. In this paper, the methods based on phonon scattering theory were applied to explore the thermal transport properties CNTs. The investigation was carried out under the conditions of temperature and axial strain. In the consideration of quantum effect, the thermal conductivity increased linearly with the growth of temperature in low-temperature section, and began to decrease gradually when the temperature exceeded a definite value. If an axial strain was concerned, there was an increasing trend of thermal conductivity as the stretch strain increases. However, after the strain exceeded a particular value the thermal conductivity decreased significantly. In addition, the high frequency phonon peak in PDOS was found to be an important parameter in describing thermal transport properties of dynamic structures.

Monte Carlo Simulation of Thermal Conductivities of Silicon Nanowires

2005 ◽  
Author(s):  
Yunfei Chen ◽  
Deyu Li ◽  
Jennifer R. Lukes ◽  
Zhonghua Ni
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Dispersion Relation ◽  
Thermal Transport ◽  
Phonon Transport ◽  
Si Nanowires ◽  
Nanowire Diameter ◽  
Energy Conversion Devices ◽  
Tens Nanometer

One-dimensional (1D) materials such as various kinds of nanowires and nanotubes have attracted considerable attention due to their potential applications in electronic and energy conversion devices. The thermal transport phenomena in these nanowires and nanotubes could be significantly different from that in bulk material due to boundary scattering, phonon dispersion relation change, and quantum confinement. It is very important to understand the thermal transport phenomena in these materials so that we can apply them in the thermal design of microelectronic, photonic, and energy conversion devices. While intensive experimental efforts are being carried out to investigate the thermal transport in nanowires and nanotube, an accurate numerical prediction can help the understanding of phonon scattering mechanisms, which is of fundamental theoretical significance. A Monte Carlo simulation was developed and applied to investigate phonon transport in single crystalline Si nanowires. The Phonon-phonon Normal (N) and Umklapp (U) scattering processes were modeled with a genetic algorithm to satisfy both the energy and the momentum conservation. The scattering rates of N and U scattering processes were given from the first perturbation theory. Ballistic phonon transport was modeled with the code and the numerical results fit the theoretical prediction very well. The thermal conductivity of bulk Si was then simulated and good agreement was achieved with the experimental data. Si nanowire thermal conductivity was then studied and compared with some recent experimental results. In order to study the confinement effects on phonon transport in nanowires, two different phonon dispersions, one based on bulk Si and the other solved from the elastic wave theory for nanowires, were adopted in the simulation. The discrepancy from the simulations based on different phonon dispersions increases as the nanowire diameter decreases, which suggests that the confinement effect is significant when the nanowire diameter goes down to tens nanometer range. It was found that the U scattering probability engaged in Si nanowires was increased from that in bulk Si due to the decrease of the frequency gap between different modes and the reduced phonon group velocity. Simulation results suggest that the dispersion relation for nanowire solved from the elasticity theory should be used to evaluate nanowire thermal conductivity as the nanowire diameter reduced to tens nanometer.

Low-temperature thermal conductivity and boson peak in the glassy g-As2S3

2016 ◽  
Vol 39 (0) ◽  
pp. 66-72
Author(s):  
В. Міца ◽  
О. Фегер ◽  
С. Петрецький ◽  
Р. Голомб ◽  
В. Ткач
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Boson Peak

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.

Sticky thermoelectric materials for flexible thermoelectric modules to capture low-temperature waste heat

MRS Advances ◽  
2020 ◽  
Vol 5 (10) ◽  
pp. 481-487 ◽  
Author(s):  
Norifusa Satoh ◽  
Masaji Otsuka ◽  
Yasuaki Sakurai ◽  
Takeshi Asami ◽  
Yoshitsugu Goto ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Waste Heat ◽  
Air Cooling ◽  
Conductive Adhesives ◽  
Hot Plate ◽  
Low Thermal Conductivity ◽  
Te Modules ◽  
P Type ◽  
Flexible Thermoelectric

ABSTRACTWe examined a working hypothesis of sticky thermoelectric (TE) materials, which is inversely designed to mass-produce flexible TE sheets with lamination or roll-to-roll processes without electric conductive adhesives. Herein, we prepared p-type and n-type sticky TE materials via mixing antimony and bismuth powders with low-volatilizable organic solvents to achieve a low thermal conductivity. Since the sticky TE materials are additionally injected into punched polymer sheets to contact with the upper and bottom electrodes in the fabrication process, the sticky TE modules of ca. 2.4 mm in thickness maintained temperature differences of ca. 10°C and 40°C on a hot plate of 40 °C and 120°C under a natural-air cooling condition with a fin. In the single-cell resistance analysis, we found that 75∼150-µm bismuth powder shows lower resistance than the smaller-sized one due to the fewer number of particle-particle interfaces in the electric pass between the upper and bottom electrodes. After adjusting the printed wiring pattern for the upper and bottom electrodes, we achieved 42 mV on a hot plate (120°C) with the 6 x 6 module having 212 Ω in the total resistance. In addition to the possibility of mass production at a reasonable cost, the sticky TE materials provide a low thermal conductivity for flexible TE modules to capture low-temperature waste heat under natural-air cooling conditions with fins for the purpose of energy harvesting.

A Setup for Studying the Low-Temperature Thermal Conductivity of Powder Samples

2005 ◽  
Vol 48 (3) ◽  
pp. 417-421 ◽  
Author(s):  
A. I. Krivchikov ◽  
B. Ya. Gorodilov ◽  
O. A. Korolyuk
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Powder Samples

Structural order in alkali-degraded PAN as seen in studies of low-temperature thermal conductivity

Polymer ◽  
1983 ◽  
Vol 24 (3) ◽  
pp. 258-262 ◽  
Author(s):  
N.S. Batty ◽  
A.J. Gradwell ◽  
J.T. Guthrie ◽  
D. Greig ◽  
N.D. Hardy ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Low Temperature ◽  
Structural Order

scholarly journals Study of anisotropic thermal conductivity in textured thermoelectric alloys by Raman spectroscopy

RSC Advances ◽  
2021 ◽  
Vol 11 (39) ◽  
pp. 24456-24465
Author(s):  
Rapaka S. C. Bose ◽  
K. Ramesh
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Transport Properties ◽  
Thermal Transport ◽  
Layered Crystal ◽  
Layered Crystal Structure ◽  
Thermal Transport Properties ◽  
Anisotropic Thermal Conductivity ◽  
P Type

Polycrystalline p-type Sb1.5Bi0.5Te3 (SBT) and n-type Bi2Te2.7Se0.3 (BTS) compounds possessing layered crystal structure show anisotropic electronic and thermal transport properties.

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