Heat transfer in different phases of solid cyclohexene

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• 作者：V.A. Konstantinov ; A.I. Krivchikov ; O.A. Korolyuk ; V.P. Revyakin ; V.V. Sagan ; G.A. Vdovichenko ; A.V. Zvonaryova
• 关键词：Thermal conductivity ; Cyclohexene ; Polymorphism ; Orientational disorder
• 刊名：Physica B
• 出版年：2013
• 出版时间：1 September, 2013
• 年：2013
• 卷：424
• 期：Complete
• 页码：54-59
• 全文大小：806 K

文摘

The thermal conductivity of solid cyclohexene C₆H₁₀ has been measured in two independent experiments in five different stable and metastable phase states: orientational glass (Ig), orientational glass (IIIg) with a partial order, dynamically orientationally disordered state (III) with a partial order, completely orientationally ordered phase (II) and ¡°plastic¡± phase (I). The measurements were carried out at saturated vapor pressure in the temperature range 2-120 K and at isochoric conditions in ¡°plastic¡± and orientationally ordered phases on samples of different densities. The isochoric thermal conductivity of ¡°plastic¡± phase increases smoothly with temperature. It can be attributed to weakening of the translational orientational coupling which, in turn, leads to a decrease in phonon scattering on rotational excitations. The thermal conductivity of cyclohexene measured at saturated vapor pressure exhibits a similar behavior in phases Ig, IIIg, and II. At low temperatures (T<8 K) the thermal conductivity tends to T² dependence^, passes through a maximum and decreases further with increasing temperature following the dependence, which is somewhat different from 1/T. It was found that the thermal conductivity can be represented as a sum of two contributions ¦Ê(T)=¦Ê₁(T)+¦Ê₂(T), where ¦Ê₁(T) is due to propagating phonons whose mean-free path exceeds half the phonon wavelength, and ¦Ê₂(T) is attributed to localized short-wavelength or ¡°diffusive¡± vibrational modes.