Nonequilibrium viscosity of glass

Communication: Resolving the vibrational and configurational contributions to thermal expansion in isobaric glass-forming systems

“…rheology, 11,12 and the many phenomenological models for glass relaxation behavior. 13,14 Our result confirms that this underlying assumption of these models is indeed well founded. However, additional investigation is necessary for systems bound by anisotropic forces.…”

“…Many phenomenological models of rheology [11][12][13] and glass relaxation behavior [14][15][16][17] implicitly assume that configurational and vibrational components of isobaric thermal expansion can be expressed as separate terms. From a statistical mechanics point of view, the separability of vibrational and configurational thermal expansions implies a factoring of the partition function into independent configurational and vibrational contributions.…”

Response to “Comment on ‘Heat capacity, enthalpy fluctuations, and configurational entropy in broken ergodic systems’” [J. Chem. Phys. 134, 147101 (2011)]

“…11,18 This, in turn, provided the framework for the first-ever comprehensive study of the temperature and thermal history dependence of glass viscosity during the glass transition-where there is a continuous loss of configurational entropy-and in the isostructural regime at even lower temperatures. 19 This approach was also essential for the recent discovery of the inherent nonmonotonic relaxation behavior of density fluctuations in glass-forming systems, which is confirmed by in situ small-angle x-ray scattering experiments. 20 Finally, the description of configurational entropy described in our work is the only one consistent with a topological view of glass structure, 21 in which the so-called "floppy modes" are shown to be the dominant contributors to configurational entropy.…”

Anomalous Enthalpy Relaxation in Vitreous Silica

“…The principle of the experimental approach of these studies is to trap the high potential energy state of a liquid by hyperquenching, and subsequently discharge the excessive energy by annealing at a certain temperature (Ta) below Tg for a certain period of time (ta), and then upscanning the annealed HQG in a differential scanning calorimeter (DSC). Liquid structure can be frozen-in by hyperquenching and thereby a higher fictive temperature (Tf) compared to Tg will be generated in glass state (Yue et al, 2002b;Kiczenski and Stebbins, 2006;Mauro et al, 2009a). With proceeding of the relaxation process, the Tf gradually decreases with increasing Ta and ta.…”