Specific features of heat transfer in the orientationally ordered phases of molecular crystals in the region with predominant phonon-phonon scattering

2015 ◽  
Vol 41 (7) ◽  
pp. 551-556 ◽  
Author(s):  
A. I. Krivchikov ◽  
O. O. Romantsova ◽  
O. A. Korolyuk ◽  
G. A. Vdovichenko ◽  
Yu. V. Horbatenko
Keyword(s):  
Heat Transfer ◽  
Phonon Scattering ◽  
Molecular Crystals ◽  
Ordered Phases

One-axis molecular rotation and phonon scattering in solid C2H6 and C2F6

Open Physics ◽  
2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Oleg Pursky ◽  
Vyacheslav Konstantinov
Keyword(s):  
Heat Transfer ◽  
Phonon Scattering ◽  
Molecular Crystals ◽  
Molecular Rotation ◽  
Rotation Effect ◽  
Total Thermal Resistance ◽  
Transfer Processes ◽  
Modified Method ◽  
Reduced Coordinates ◽  
The One

AbstractUsing solid C2H6 and C2F6 as an example, the one-axis molecular rotation effect on thermal conductivity has been considered in orientationally-ordered (OO) and orientationally-disordered (OD) phases of simple molecular crystals. The influence of molecular rotation on the heat transfer processes has been studied by a modified method of reduced coordinates, which permitted separating phonon-phonon and phonon-rotation contributions to the total thermal resistance.

scholarly journals Statistical model of phonon scattering on rough boundaries of nanostructures

2021 ◽  
Vol 2057 (1) ◽  
pp. 012111
Author(s):  
A A Barinov ◽  
V I Khvesyuk
Keyword(s):  
Heat Transfer ◽  
Statistical Model ◽  
Phonon Scattering ◽  
Rapid Development ◽  
Decisive Role ◽  
Comprehensive Analysis ◽  
Urgent Task ◽  
Semiconductor Electronics ◽  
Ballistic Heat Transfer ◽  
Rough Boundaries

Abstract Because of the rapid development of semiconductor electronics and the tendency to size reduction of the elements of transistors, there is an urgent task of assessing the heat transfer regime, which determines the ability to maintain the required thermal regime. In this work, the heat transfer in micro- and nanostructures in silicon is considered, and a comprehensive analysis of factors determining the heat transfer regime is carried out. In particular, the effect of the interaction of phonons with the sample boundaries in the quasi-ballistic and ballistic heat transfer regimes, where these processes play a decisive role, is evaluated using statistical model of phonon scattering on rough boundaries of samples.

Role of nonlocal exchange in molecular crystals: The case of two proton-ordered phases of ice

2011 ◽  
Vol 32 (10) ◽  
pp. 2177-2185 ◽  
Author(s):  
Frédéric Labat ◽  
Claude Pouchan ◽  
Carlo Adamo ◽  
Gustavo E. Scuseria
Keyword(s):  
Molecular Crystals ◽  
Ordered Phases

scholarly journals Thermal effects of high energy and ultrafast lasers

2015 ◽  
Author(s):  
◽  
Nazia Afrin
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Heat Transport ◽  
Phonon Scattering ◽  
Heated Surface ◽  
High Energy ◽  
Electron Interaction ◽  
Energy Laser ◽  
High Energy Laser

Heat transfer describes the exchange of thermal energy, between physical systems depending on the temperature and pressure, by dissipating heat. The fundamental modes of heat transfer are conduction or diffusion, convection and radiation. Heat and mass transfer are kinetic processes that may occur and be studied separately or jointly. Studying them apart is simpler, but both processes are modeled by similar mathematical equation in the case of diffusion and convection. There are complex problems where heat and mass transfer processes are combined with chemical reactions, as in combustion. The resulting behavior of heat transport in microscale will be very different from macroscale heat transfer based on the averages taken over hundreds of thousands of grains (in space) and collision (in time). From the microscopic point of view, the process of heat transport is governed by phonon-electron interaction in metallic films and by phonon scattering in dielectric films, insulators and semi-conductors. For extremely heated surfaces by high energy laser pulse, it is very difficult to measure temperature of flux at the heated surface because of the unendurable capacity of the conventional sensors. Laser is the tool of choice when drill holes ranging in diameter from several millimeters to less than one micro-meter. Instead of having advanced melting and resolidification modeling process recently, the inherent uncertainties of the input parameters can directly cause unstable characteristics of the output results which means the parametric uncertainties may influence the characteristics of the phase change processes (melting and resolidification) which will affect the predictions of interfacial properties i.e., temperature, velocity and mainly the location of solid-liquid interface. All of those processes can be considered under high energy laser interaction with materials.

Study of the thermal conductivity of a metal-coated multi-walled carbon nanotube using molecular dynamics atomistic simulations

MRS Advances ◽  
2019 ◽  
Vol 4 (08) ◽  
pp. 507-513 ◽  
Author(s):  
Dinesh Bommidi ◽  
Ravindra Sunil Dhumal ◽  
Iman Salehinia
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
Phonon Scattering ◽  
Metal Coating ◽  
Atomistic Simulations ◽  
Multi Walled Carbon Nanotube

ABSTRACTThermal conductivity of a nickel-coated tri-wall carbon nanotube was studied using molecular dynamics where both the phonon and electron contributions were considered. Simulations predicted a significant effect of the metal coating on the thermal conductivity, i.e. 50% decrease for 1.2 nm of Ni coating. However, the decreasing rate of the thermal conductivity is minuscule for the metal thicker than 1.6 nm. The smaller thermal conductivity of the metal coating, phonon scattering at the interface, and less impacted heat transfer on the inner tubes of the carbon nanotube rationalized the observed trends.

Modeling and Prediction of Sub-Micrometer Heat Transfer During Thermomechanical Data Storage

1999 ◽  
Author(s):  
William P. King ◽  
Juan G. Santiago ◽  
Thomas W. Kenny ◽  
Kenneth E. Goodson
Keyword(s):  
Heat Transfer ◽  
Data Storage ◽  
Phonon Scattering ◽  
Heat Rate ◽  
Phonon Transport ◽  
Polymer Layer ◽  
Spatial Density ◽  
Atomic Force ◽  
Data Layer ◽  
Gas Conduction

Abstract Heat transfer governs the bit size and writing rate during sub-micrometer thermomechanical data storage with Atomic Force Microscope (AFM) cantilevers. The present work predicts the temperature distribution and rates of heat flow in the AFM tip and the substrate as functions of the peak cantilever temperature, the diameter of the tip-substrate contact, and the thickness of the deforming polymer coating on the silicon substrate. The calculations consider increased phonon scattering, radiation losses, and gas conduction losses at the silicon tip boundaries. Nearly ballistic phonon transport in the tip augments the dependence of the heat rate into the polymer on the tip-polymer contact diameter. For a cantilever heater temperature of 700 K and a polymer layer thickness of 80 nm, the temperature at the tip-polymer interface is predicted for contact diameters from 4 nm to 50 nm. This work models the deformation of the polymer layer during data writing and predicts data bit size as a function of tip temperature and writing time. These simulations will help optimize the design of the cantilever and the polymer data layer, with the goal of increasing the spatial density and rate of bit formation.

THERMAL TRANSPORT OF MgB2 SUPERCONDUCTORS: INTERPLAY BETWEEN ELECTRON AND LATTICE-IMPURITY SCATTERING

2007 ◽  
Vol 21 (26) ◽  
pp. 4517-4536 ◽  
Author(s):  
DINESH VARSHNEY ◽  
M. NAGAR ◽  
K. K. CHOUDHARY
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phonon Scattering ◽  
Theoretical Calculations ◽  
Impurity Scattering ◽  
Metallic Phase ◽  
Scattering Mechanism ◽  
S Wave ◽  
Lattice Contribution ◽  
Relaxation Time Approximation

We use the Kubo model to calculate the lattice contribution to the thermal conductivity (κph) in MgB 2 superconductors. The theory is formulated when heat transfer is limited by the scattering of phonons from defects, grain boundaries, charge carriers, and phonons. The lattice thermal conductivity in normal state of MgB 2 superconductors dominates and is an artifact of strong phonon-impurity and -phonon scattering mechanism. Later on, the electronic contribution to the thermal conductivity (κe) is calculated within relaxation time approximation for π and σ band carriers with s wave symmetry. Such an estimate sets an upper bound on κe and is about 30% of the total heat transfer at room temperature. The validity of the Wiedemann Franz law is also examined and an enhanced Lorenz number is obtained. Both these channels for heat transfer are clubbed and κ tot develops a broad peak at about 120 K, before falling off at higher temperatures weakly. The anomalies reported are well-accounted in terms of the scattering mechanism by phonon and electron with impurities. It is shown that the behavior of the thermal conductivity is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between electron and lattice contributions. The contribution of carriers toward κ is substantial and is due to the fact that the carriers are condensed and do not carry entropy. We include comparisons with other theoretical calculations on κe and available experimental data. The numerical analysis of heat transfer in the metallic phase of MgB 2 shows similar results as those revealed from experiments.

Translation-rotation coupling and heat transfer in orientationally-disordered phase of CCl4

Open Physics ◽  
2006 ◽  
Vol 4 (2) ◽  
Author(s):  
Oleg Pursky ◽  
Vyacheslav Konstantinov
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Free Path ◽  
Phonon Scattering ◽  
Mean Free Path ◽  
Mobility Edge ◽  
Total Thermal Resistance ◽  
Disordered Phase ◽  
Diffusive Modes

AbstractThe isochoric thermal conductivity of an orientationally-disordered phase of CCl4 is analysed within a model in which heat is transferred by phonons and above the phonon mobility edge by ”diffusive” modes migrating randomly from site to site. The mobility edge ω0 is found from the condition that the phonon mean-free path cannot become smaller than half the phonon wavelength. The contributions of phonon-phonon, one-, and two-phonon scattering to the total thermal resistance of solid CCl4 are calcualted under the assumption that the different scattering mechanisms contribute additively. An increase in the isochoric thermal conductivity with temperature is explained by suppression of phonon scattering at rotational excitations due to a decrease in correlation in the rotation of neighbouring molecules.

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