Thermal oscillations, second sound and thermal resonance in phonon hydrodynamics

2021 ◽  
Vol 477 (2247) ◽  
Author(s):  
Mingtian Xu
Keyword(s):  
Relaxation Time ◽  
Heat Source ◽  
Recent Observation ◽  
Phonon Transport ◽  
Single Frequency ◽  
Second Sound ◽  
At Resonance ◽  
Low Dimensional ◽  
Thermal Oscillations ◽  
Low Dimensional Materials

Recent observation of second sound in graphite at a temperature above 100 K has aroused a great interest in the study of thermal waves in non-metallic solid materials. In this article, based on the Guyer–Krumhansl model, we investigate the second sound and thermal resonance phenomena in phonon hydrodynamics. The occurrence condition for the second sound is derived. It shows that the smaller the relaxation time of N-scattering of the non-metallic solid with a large relaxation time of R-scattering, the more likely the second sound will occur. For the phonon transport in the non-metallic solid excited by an oscillatory heat source with a single frequency, the occurrence condition for thermal resonance and a formula for calculating the external heat source frequency at resonance are also derived. It is found that the low-dimensional materials with small size are prone to the occurrence of second sound and thermal resonance. These phenomena open up new avenues for thermal management and energy conversion.

scholarly journals Mach Fronts in Random Media with Fractal and Hurst Effects

2021 ◽  
Vol 5 (4) ◽  
pp. 229
Author(s):  
Junren Ran ◽  
Martin Ostoja-Starzewski ◽  
Yuriy Povstenko
Keyword(s):  
Relaxation Time ◽  
Heat Source ◽  
Random Fields ◽  
Random Media ◽  
Second Order ◽  
Heat Sources ◽  
Second Sound ◽  
Homogeneous Domain ◽  
Stochastic Fluctuations

An investigation of transient second sound phenomena due to moving heat sources on planar random media is conducted. The spatial material randomness of the relaxation time is modeled by Cauchy or Dagum random fields allowing for decoupling of fractal and Hurst effects. The Maxwell–Cattaneo model is solved by a second-order central differencing. The resulting stochastic fluctuations of Mach wedges are examined and compared to unperturbed Mach wedges resulting from the heat source traveling in a homogeneous domain. All the examined cases are illustrated by simulation movies linked to this paper.

scholarly journals The Highly Uniform Photoresponsivity from Visible to Near IR Light in Sb2Te3 Flakes

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1535
Author(s):  
Shiu-Ming Huang ◽  
Jai-Lung Hung ◽  
Mitch Chou ◽  
Chi-Yang Chen ◽  
Fang-Chen Liu ◽  
...  
Keyword(s):  
Band Structure ◽  
Energy Difference ◽  
Experimental Result ◽  
Light Illumination ◽  
Near Ir ◽  
State Band ◽  
Valence Bands ◽  
Low Dimensional ◽  
Low Dimensional Materials ◽  
Ir Light

Broadband photosensors have been widely studied in various kinds of materials. Experimental results have revealed strong wavelength-dependent photoresponses in all previous reports. This limits the potential application of broadband photosensors. Therefore, finding a wavelength-insensitive photosensor is imperative in this application. Photocurrent measurements were performed in Sb2Te3 flakes at various wavelengths ranging from visible to near IR light. The measured photocurrent change was insensitive to wavelengths from 300 to 1000 nm. The observed wavelength response deviation was lower than that in all previous reports. Our results show that the corresponding energies of these photocurrent peaks are consistent with the energy difference of the density of state peaks between conduction and valence bands. This suggests that the observed photocurrent originates from these band structure peak transitions under light illumination. Contrary to the most common explanation that observed broadband photocurrent carrier is mainly from the surface state in low-dimensional materials, our experimental result suggests that bulk state band structure is the main source of the observed photocurrent and dominates the broadband photocurrent.

scholarly journals Definition of a scoring parameter to identify low-dimensional materials components

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Peter Mahler Larsen ◽  
Mohnish Pandey ◽  
Mikkel Strange ◽  
Karsten Wedel Jacobsen
Keyword(s):  
Definition Of ◽  
Low Dimensional ◽  
Low Dimensional Materials

scholarly journals Multiple Exciton Generation in Isolated and Interacting Silicon Nanocrystals

Nanoscale ◽  
2021 ◽  
Author(s):  
Ivan Marri ◽  
Stefano Ossicini
Keyword(s):  
Renewable Energy ◽  
Solar Cell ◽  
Silicon Nanocrystals ◽  
Photovoltaic Systems ◽  
Multiple Exciton Generation ◽  
Important Challenge ◽  
Low Dimensional ◽  
Low Dimensional Materials

An important challenge in the field of renewable energy is the development of novel nanostructured solar cell devices which implement low-dimensional materials to overcome the limits of traditional photovoltaic systems....

Reasonably designed 2D WS2 and CdS microwire heterojunction for high performance photoresponse

Nanoscale ◽  
2021 ◽  
Author(s):  
Z.Q. Zheng ◽  
Yuchen Zhou ◽  
Wei Gao ◽  
Li Zhang ◽  
Mengmeng Yang ◽  
...  
Keyword(s):  
High Performance ◽  
Low Dimensional ◽  
Low Dimensional Materials

Heterojunctions based on low-dimensional materials can combine the superiorities of each composition and realize novel properties. Herein, a mixed-dimensional heterojunction comprising multilayer WS2, CdS microwire and few-layer WS2 has been...

Potential SiX (X = N, P, As, Sb, Bi) homo-bilayers for visible-light photocatalysts application

2021 ◽  
Author(s):  
Radha Somaiya ◽  
Deobrat Singh ◽  
Yogesh Kumar Sonvane ◽  
Sanjeev Kumar Gupta ◽  
Rajeev Ahuja
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Photocatalytic Water Splitting ◽  
Low Dimensional ◽  
Low Dimensional Materials

Low dimensional materials possess a challenge to identify a photocatalyst suitable for photocatalytic water splitting application. We have systematically investigated that SiN, SiP, and SiAs homo-bilayers are efficient for water...

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