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Dielectric α relaxation of supercooled sugar alcohols
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| Title: | Dielectric α relaxation of supercooled sugar alcohols |
| Other Titles: | 過冷却糖アルコールの誘電α緩和 |
| Authors: | 川谷, 維摩 Browse this author |
| Issue Date: | 25-Mar-2024 |
| Publisher: | Hokkaido University |
| Abstract: | Glass transition phenomena is one of the most important problem of physics. Investigation of supercooled liquids is useful to clarify phenomena related to glass transitions. It has been pointed out in several literatures that dielectric α process doesn't follow the Vogel-Fulcher-Tammann (VFT) equation near Tg even the experiments had been performed under the condition where the sample system is well relaxed to thermodynamic equilibrium state. It is necessary to investigate whether the glass transition is simply a relaxation phenomenon due to the finite observation time, or it is some kind of transition where a change in dynamics occurs. It is considered that such claims have been increased after accessible frequency range of dielectric spectroscopy had attained low frequencies such as sub-milli Hz region. In this case, it is concerned that the thermodynamical condition meets well-relaxed equilibrium state. In this study, we re-examine the behavior of the α process using typical glass formers sorbitol, xylitol and glycerol in an extremely wide frequency from 110 MHz down to 10 μHz paying attention to the thermal history of the sample during the entire measurements to precise measurement. It is found that the behavior of the α process in sorbitol depends on the thermal history. Near Tg, the α process doesn ’t follow the VFT equation derived from experimental data well above Tg. This indicates that the α process cannot be represented by a simple function from high temperature to low temperature just above the glass transition temperature. However, the divergence manner of the α relaxation frequency at a finite temperature is kept even near Tg. The results suggest that the glass transition is not just a relaxation phenomenon but some kind of transition with a changing dynamics. This article is devided into five chapters. In chapter 1, we will give you an overview of reserch on supercooled liquids and glass transitions, and the motivation for this study will be presented. In chapter 2, we recall the basic knowledge of dielectric relaxation phenomena to helping discussions in following chapters. In chapter 3, the effect of electrode structure on relaxation frequency is examined. In chapter 4, we will discuss the effect of thermal history on the relaxation frequency. Chapter 5 contains the conclusion of this thesis. |
| Conffering University: | 北海道大学 |
| Degree Report Number: | 甲第15738号 |
| Degree Level: | 博士 |
| Degree Discipline: | 理学 |
| Examination Committee Members: | (主査) 准教授 三品 具文, 教授 根本 幸児, 客員教授 長尾 忠昭, 名誉教授 野嵜 龍介 |
| Degree Affiliation: | 理学院（物性物理学専攻） |
| Type: | theses (doctoral) |
| URI: | http://hdl.handle.net/2115/92275 |
| Appears in Collections: | 学位論文 (Theses) > 博士 （理学）
課程博士 (Doctorate by way of Advanced Course) > 理学院(Graduate School of Science)
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