Cluster relaxation dynamics in liquids and solids near the glass-transformation temperature

• Опубліковано в: : Физика низких температур
• Дата: 2007
• Автор: Kokshenev, V.B.
• Формат: Стаття
• Мова: Англійська
• Опубліковано: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2007
• Теми: Related Topics
• Онлайн доступ: https://nasplib.isofts.kiev.ua/handle/123456789/121798
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Цитувати: Cluster relaxation dynamics in liquids and solids near the
 glass-transformation temperature/ V.B. Kokshenev // Физика низких температур. — 2007. — Т. 33, № 6-7. — С. 805-813. — Бібліогр.: 34 назв. — англ.

The structural relaxation in glass forming materials is studied near the glass transformation temperature
 Tg indicated by the heat capacity maximum. The late-time asymptote of the Kohlrausch–Williams–Watts
 form of the relaxation function is rationalized via the mesoscopic-scale correlated regions in terms of the
 Debye-type clusters following the dynamic scaling law. It is repeatedly shown that regardless of underlying
 microscopic realizations in glass formers with site disorder the structural relaxation is driven by local random
 fields, described via the directed random walks model. The relaxation space dimension ds = 3 at Tg is
 suggested for relaxing units of fractal dimension d f = 5/2 for quadrupolar-glass clusters in ortho–para hydrogen
 mixtures, that is compared with entangled-chain clusters in polymers (d f = 1) and solid-like clusters
 relaxing in supercooled molecular liquids (with ds = 6 and d f = 3). The relaxation dynamics of
 orientational-glass clusters in plastic crystals is attributed to the model of continuos time random walks in
 space ds = 6. As a by-product, the expansivity in polymers, molecular liquids and networks is predicted.