Dielectric relaxation processes in water-in-sorbitol mixtures
Dielectric relaxation processes in water-in-sorbitol mixtures
复制标题
山梨醇水混合物中的介电弛豫过程
DOI：
10.1016/s0022-3093(02)01495-3
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发表时间：
2002
影响因子：
3.5
通讯作者：
Kei Kitai
中科院分区：
文献类型：
--
作者：
R. Nozaki;H. Zenitani;A. Minoguchi;Kei Kitai
在10 μHz ~ 500 MHz的频率范围内，在263 ~ 346 K的温度范围内，对含水率为0 ~ 0.5的山梨醇含水混合物进行了复介电常数测量。观察到两个介电弛豫过程，α和β过程。α过程服从Vogel-Fulcher-Tammann模型，而β过程服从Arkenius型温度依赖性。β过程在温度升高的温度区域内与α过程合并。在无水山梨醇中加入少量水，α过程的弛豫时间发生剧烈变化，而β过程的弛豫时间变化不大。山梨醇水混合物中α过程的行为支持了协同重排区的存在。基于目前的实验结果，从微观角度考虑，山梨醇分子之间存在取向相关性，提供了作为热活化过程的β弛豫。
Complex permittivity measurements were performed on water-in-sorbitol mixtures with molar water fraction from 0 to 0.5 in the frequency range between 10 μHz and 500 MHz at temperatures from 263 up to 346 K. Two dielectric relaxation processes, α and β processes, were observed. The α process obeys the Vogel–Fulcher–Tammann manner while the β process follows the Arrhenius-type temperature dependence. The β process merges into the α process in a temperature region with increasing temperature. Adding small amount of water into anhydrous sorbitol brings drastic change in the relaxation time of the α process but not in that of the β process. The behavior of the α process in the water-in-sorbitol mixtures supports the existence of the cooperatively rearranging region. Considerations based on present experimental results from the microscopic point of view suggest that there is orientational correlation among the sorbitol molecules providing the β relaxation as a thermally activated process.