异常(物理)
凝聚态物理
热导率
材料科学
微晶
无定形固体
阿累尼乌斯方程
相变
相(物质)
高原(数学)
电导率
热力学
活化能
化学
结晶学
物理
物理化学
数学分析
数学
有机化学
冶金
复合材料
作者
Daria Szewczyk,А. И. Кривчиков,A. Jeżowski
标识
DOI:10.1088/2399-6528/ad1bb5
摘要
Abstract The temperature dependencies of the thermal conductivity coefficient, κ(T), in 1-fluoroadamantane were investigated for two different orientationally-disordered states. In the first one, κ(T) exhibits a crystalline character with a typical maximum and two anomalous regions marked at higher temperatures. Here, the low-temperature power-law dependence is reduced due to a relatively large contribution of dislocations and defects in the polycrystalline sample. Above 196 K, there is an anomalous plateau in thermal conductivity resulting from the presence of an intermediate centrosymmetric state. Further, a significant increase in κ occurs above 234 K, resulting from a phase transition to a high-temperature disordered cubic phase. Subsequent cooling of the sample leads to an irreversible transition towards a disordered state resulting in a κ(T) dependence corresponding to an amorphous material behavior. The primary anomaly at 196 K disappears, while the second one associated with the phase transition at 227 K shifts towards lower temperatures. The irreversibility of this transformation is also verified by scanning microscopy images. Thermal conductivity in both phases has an additional contribution of an Arrhenius type in their temperature dependences.
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