Investigation of the thermal conductivity of molecular crystals

Chudnovskii, A. F.; Mogilevskii, B. M.; Surin, V. G.

doi:10.1007/bf00832672

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…At high temperatures the thermal conductivity of simple molecular crystals in the orientationally ordered phases is expected to follow the 1/T law [15][16][17][18][19][20]. As noticed above, here we observe a noticeable deviation of the curves k(T) from this law.…”

Section: Methodssupporting

confidence: 73%

“…Current theoretical approaches for phonon-phonon scattering processes are able to formulate at best, semiquantitative predictions concerning the temperature dependence of the thermal conductivity [15,20]. The theory of phonon-phonon scattering is however able to provide an estimate for the coefficient À of the T -1 term in Eq.…”

Section: Experimental Evidence Of the Role Of Quasilocalized Phonons mentioning

confidence: 99%

“…(1). In fact, such a coefficient can be calculated for molecular crystals by Slack's approximation [27], as [20]:…”

Section: Experimental Evidence Of the Role Of Quasilocalized Phonons mentioning

confidence: 99%

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Experimental evidence of the role of quasilocalized phonons in the thermal conductivity of simple alcohols in orientationally ordered crystalline phases

Кривчиков¹,

Sharapova²,

Korolyuk³

et al. 2009

Low Temperature Physics

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The thermal conductivity k(T) of crystalline alcohols (methyl, ethyl and 1-propyl) within their thermodynamic equilibrium phases for T ³ 2 K and under the equilibrium vapor pressures has been measured and analyzed. While such compounds usually exhibit a rich polymorphism including amorphous and partially ordered crystals, the phases here explored correspond to crystals showing complete orientational order. The results show that the temperature dependence of k(T) above its maximum deviates from the expected decrease following a 1/Ò law with increasing temperature arising from anharmonic interactions involving acoustic excitations. Such a deviation is here attributed to the presence of a component k II (T) corresponding to the shortest-lifetime phonons (Cahill-Pohl model) additional to that k I (T) related to propagating phonons and thus: k(T) = k I (T) + k II (T). Above T = 40 K k I (T) does follow the law 1/Ò and k II (T) is basically temperature independent. The component k I (T) is well described by the Debye-Peierls model taking into account the phonon-phonon Umklapp processes and phonon scattering by dislocations. In turn, the contribution k II (T) is attributed to the effects of higher lying excitations which get thermally populated above some 40 K. Finally, a systematic trend is found concerning the strength of phonon-phonon scattering which is seen to diminish as the number of carbon atoms in the alcohol molecule increases. PACS: 66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves; 63.20.-e Phonons in crystal lattices.

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Section: Methodssupporting

confidence: 73%

Section: Experimental Evidence Of the Role Of Quasilocalized Phonons mentioning

confidence: 99%

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Experimental evidence of the role of quasilocalized phonons in the thermal conductivity of simple alcohols in orientationally ordered crystalline phases

Кривчиков¹,

Sharapova²,

Korolyuk³

et al. 2009

Low Temperature Physics

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“…22 Such a maximum is known to mark the transition from phonon-phonon scattering to phonon scattering on defects in ordered crystals. [48][49][50] To highlight such deviation from the T −1 law, Fig. 4 shows κ(T )·T in the form…”

Section: B Orientationally Ordered Phasesmentioning

confidence: 99%

Effects of internal molecular degrees of freedom on the thermal conductivity of some glasses and disordered crystals

et al. 2012

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The thermal conductivity κ(T ) of the fully ordered stable phase II, the metastable phase III, the orientationally disordered (plastic) phase I, as well as the nonergodic orientational glass (OG) phase, of the glass former cyclohexanol (C 6 H 11 OH) has been measured under equilibrium vapor pressure within the 2-200 K temperature range. The main emphasis is here focused on the influence of the conformational disorder upon the thermal properties of this material. Comparison of results with those regarding cyanoclyclohexane (C 6 H 11 CN), a chemically related compound, serves to quantify the role played by the terminal groups -OH and -CN on the phonon scattering processes. The picture that emerges shows that motions of such groups do play a minor role as scattering centers, both within the low-temperature orientationally ordered phases as well as in the OG states. The results are analyzed within the Debye-Peierls relaxation time model for isotropic solids comprising mechanisms for long-wave phonon scattering within the OG and orientational ordered low-temperature phases, as well as others arising from localized short-wavelength vibrational modes as pictured by the Cahill-Pohl model. By means of complementary neutron and Raman scattering we show that in the OG state the energy landscapes for both compounds are very similar.

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