High-Temperature Thermoconductivity of Nitrogen-Type Crystals

Kokshenev, V. B.; Krupskii, I. N.; Kravchenko, Yu.G.

doi:10.1590/s0103-97331997000400013

Cited by 6 publications

(4 citation statements)

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“…The contribution of phonon-libron scattering was considered by (Manzhelii et al, 1975), and (Kokshenev et al, 1997). In harmonic approximation decomposition of the interaction energy with respect to translational and angular displacements of molecules near equilibrium positions can be written as …”

Section: Phonon-libron Scatteringmentioning

confidence: 99%

“…That involves considerable difficulties to describe this case with analytical expressions. As a consequence, a simplified model where the translational and orientational subsystems are described independently is usually used (Manzhelii et al, 1997;Kokshenev et al, 1997). The coupling produces a shift of phonons frequency with respect to the harmonic value as well as a broadening of bands, associated to the finite phonon lifetime.…”

Section: Introductionmentioning

confidence: 99%

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Heat Transfer in Molecular Crystals

Konstantinov¹

2011

Heat Transfer - Theoretical Analysis, Experimental Investigations and Industrial Systems

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Section: Phonon-libron Scatteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Heat Transfer in Molecular Crystals

Konstantinov¹

2011

Heat Transfer - Theoretical Analysis, Experimental Investigations and Industrial Systems

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“…For the 1/T -dependence to be valid, it is necessary that the crystal volume remain constant; otherwise, vibrational modes would change, which would result in a different temperature dependence of thermal conductivity. The results of numerous experimental studies of thermal conductivity demonstrate considerable deviations from the above dependence [2][3][4][5][6][7]. In particular, the high-temperature thermal conductivity of orientationally-ordered (OO) molecular crystals decreases with temperature growth by the dependence Λ ∝ T −n , where n < 1 in the isochoric case, and 1 < n < 2 at constant pressure.…”

Section: Introductionmentioning

confidence: 99%

Thermal expansion effect on heat transfer processes in orientationally-ordered molecular crystals

Pursky¹,

Konstantinov²

2009

J. Phys. Stud.

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The influence of the thermal expansion on heat transfer processes has been considered in orientationally ordered molecular crystals. A modified method of reduced coordinates was used to separate phonon-phonon and phonon-rotational contributions to the total thermal resistance in isobaric and isochoric cases. It was shown that a discrepancy between temperature dependences of the isobaric (Λp) and isochoric (Λv) thermal conductivity is mainly governed by the intensity of a phonon-phonon interaction because the phonon-rotational component of thermal resistance weakly depends on thermal expansion.

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“…Therefore, in reality, a simplified method is often used for separating the contributions from each of the phonon scattering mechanisms to the thermal conductivity. In such a description it is assumed that the translation-rotation coupling results only in a renormalization of the dispersion law, while the orientational vibrations make an additional contribution to the total thermal resistance of the crystal W = 1/Λ [5]. In this work, the influence of one-axis rotation of molecules on the heat transfer processes in the OO α-phase of C 2 H 6 and OD β-phase of C 2 F 6 is studied by the modified method of reduced coordinates [6], which separates the contributions of phonon-phonon and phonon-rotational scattering to the total thermal resistance W .…”

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confidence: 99%

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

Pursky

Konstantinov²

2011

Open Physics

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Abstract:Using solid C 2 H 6 and C 2 F 6 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 phononrotation contributions to the total thermal resistance. Molecular crystals possess a number of peculiarities, which can significantly influence the dynamics of the crystalline lattice. In molecular crystals, along with translation oscillations of molecules, it is necessary to consider the orientational movement of molecules as a whole, intramolecular rotation of molecular segments, and intramolecular oscillations. The requirement to take account of each additional kind (as compared with that in atomic crystal) of heat motion is a significant constraint on the construction of theoretical models. At the same time, by choosing corresponding experimental materials, we can exclude one or other type of heat motion from consider- * E-mail: Pursky_O@ukr.net (Corresponding author) † E-mail: Konstantinov@ilt.kharkov.ua ation. For example, intramolecular rotation of molecular segments in simple molecular crystals (SMC) can be disregarded owing to the simplicity of the molecular structure. In most cases the energy of intramolecular coupling in SMC considerably exceeds the energy of intermolecular interactions. Respectively, intermolecular oscillations give no significant contribution, as a rule, to the dynamics of SMC up to the melting point of the material. Thus, while considering the heat motion in SMC, we may restrict ourselves to the account of translation oscillations at sites of the crystal lattice and the orientational motion of molecules as a whole. Specific features of the dynamics of translational and orientational subsystem of crystals affect their thermodynamic properties and must manifest themselves in one way or another in the processes of relaxation. This is related, first of all, to the coupling (known as translation-rotation coupling) between translation dis-257 PACS

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High-Temperature Thermoconductivity of Nitrogen-Type Crystals

Cited by 6 publications

References 0 publications

Heat Transfer in Molecular Crystals

Heat Transfer in Molecular Crystals

Thermal expansion effect on heat transfer processes in orientationally-ordered molecular crystals

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

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