Dielectric relaxation processes in supercooled polyhydric alcohols and their mixtures

Minoguchi, Ayumi; Kaneko, Toshiya; Sotokawa, Hajime; Nozaki, Ryusuke

doi:10.1016/j.jnoncrysol.2006.04.026

Cited by 12 publications

(11 citation statements)

References 18 publications

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“…3 demonstrates that, despite different temperature dependences of the α-relaxation times in both materials, their β-relaxation times coincide at T b T g . This fact was already reported in an earlier work by Minoguchi et al [31] and found also for other polyols and their mixtures [46]. One may ask how this finding can be brought in line with the concept of a universal JG β-relaxation, which is assumed to be inherent to the glassy state of matter.…”

Section: Resultssupporting

confidence: 75%

High-frequency dynamics of type B glass formers investigated by broadband dielectric spectroscopy

Kastner

Köhler

Goncharov

et al. 2011

Journal of Non-Crystalline Solids

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a b s t r a c t a r t i c l e i n f oWe present the results of broadband dielectric spectroscopy on two glass formers with strong JohariGoldstein β-relaxations. In addition to the α-and β-relaxation dynamics, the extension of the spectra up to 1 THz also allows revealing information on the fast β-process in this class of materials. There is clear evidence for a fast process contributing in the region of the high-frequency loss minimum, which is analyzed in terms of the idealized mode-coupling theory.

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Section: Resultssupporting

confidence: 75%

High-frequency dynamics of type B glass formers investigated by broadband dielectric spectroscopy

Kastner

Köhler

Goncharov

et al. 2011

Journal of Non-Crystalline Solids

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“…Despite their simple molecular structure, hydrogen-bonding liquids (especially polyhydric alcohols) often maintain a supercooled state without crystallization, and consequently a variety of materials are available for studies on glass transition. For this reason, hydrogen-bonding liquids can sometimes enable systematic study based on differences in molecular structure; actually, they have long been used in studies on glass transition [1][2][3][4][5][6][7][8][9]. Interesting systematic features of the glass transition of polyhydric alcohols have been revealed through recent experimental studies [3][4][5][6][7][8][9], the results of which should inspire new theoretical approaches to studying the glass transition of hydrogen-bonding liquids.…”

Section: Introductionmentioning

confidence: 99%

Model of the cooperative rearranging region for polyhydric alcohols

Nakanishi

Nozaki

2011

Phys. Rev. E

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A simplified model of a hydrogen-bonding network is proposed in order to clarify the microscopic structure of the cooperative rearranging region (CRR) in Adam-Gibbs theory [G. Adam and J. H. Gibbs, J. Chem. Phys. 43, 139 (1965)]. Our model can be solved analytically, and it successfully explains the reported systematic features of the glass transition of polyhydric alcohols. In this model, hydrogen bonding is formulated based on binding free energy. Assuming a cluster of molecules connected by double hydrogen bonds is a CRR and approximating the hydrogen-bonding network as a Bethe lattice in percolation theory, the temperature dependence of the structural relaxation time can be obtained analytically. Reported data on relaxation times are well described by the obtained equation. By taking the lower limit of the binding free energy with this equation, the Vogel-Fulcher-Tammann equation can be derived. Consequently, the fragility index and glass transition temperature can be expressed as functions of the number of OH groups in a molecule, and this relation agrees well with the reported experimental data.

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“…Employing these materials, it is possible to vary the physical properties gradually by changing Nc, and therefore one can perform a systematic investigation to discuss about origin of the dielectric relaxation processes. Actually, it is pointed out that some dynamical properties, such as the relaxation time, the relaxation strength, the fragility index for the a process [12] exhibit systematic variations against the carbon number Nc [13][14][15]. These features would be closely connected to the mechanism dominating the glass transition in the sugar alcohols.…”

Section: Introductionmentioning

confidence: 99%