Shear viscosity of glass-forming melts in the liquid-glass transition region

Journal Article · Thu Apr 15 00:00:00 EDT 2010 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S106377611004014X· OSTI ID:21443552

Sanditov, D. S., E-mail: Sanditov@bsu.r ^[1]

---

1. Buryat State University (Russian Federation)

A new approach to interpreting the hole-activation model of a viscous flow of glass-forming liquids is proposed. This model underlies the development of the concept on the exponential temperature dependence of the free energy of activation of a flow within the range of the liquid-glass transition in complete agreement with available experimental data. The 'formation of a fluctuation hole' in high-heat glass-forming melts is considered as a small-scale low-activation local deformation of a structural network, i.e., the quasi-lattice necessary for the switching of the valence bond, which is the main elementary event of viscous flow of glasses and their melts. In this sense, the hole formation is a conditioned process. A drastic increase in the activation free energy of viscous flow in the liquid-glass transition region is explained by a structural transformation that is reduced to a limiting local elastic deformation of the structural network, which, in turn, originates from the excitation (critical displacement) of a bridging atom like the oxygen atom in the Si-O-Si bridge. At elevated temperatures, as a rule, a necessary amount of excited bridging atoms (locally deformed regions of the structural network) always exists, and the activation free energy of viscous flow is almost independent of temperature. The hole-activation model is closely connected with a number of well-known models describing the viscous flow of glass-forming liquids (the Avramov-Milchev, Nemilov, Ojovan, and other models).

• OSTI ID: 21443552
• Journal Information: Journal of Experimental and Theoretical Physics, Vol. 110, Issue 4; Other Information: DOI: 10.1134/S106377611004014X; Copyright (c) 2010 Pleiades Publishing, Ltd.; ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
DEFORMATION
EXCITATION
FLUCTUATIONS
FREE ENERGY
GLASS
HEAT
HOLES
LIQUIDS
OXYGEN
PHASE TRANSFORMATIONS
SHEAR
TEMPERATURE DEPENDENCE
VALENCE
VISCOSITY
VISCOUS FLOW
ELEMENTS
ENERGY
ENERGY-LEVEL TRANSITIONS
FLUID FLOW
FLUIDS
NONMETALS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
VARIATIONS