Obstruction model of the fractional Stokes–Einstein relation in glass-forming liquids
1998; Elsevier BV; Volume: 235-237; Linguagem: Inglês
10.1016/s0022-3093(98)00501-8
ISSN1873-4812
Autores Tópico(s)Glass properties and applications
ResumoDiffusion of tracer molecules in glass-forming liquids is modeled in terms of diffusion in an obstructed space. The obstructions, which model heterogeneities in supercooled liquids, are taken to be spherical and frozen in position for simplicity. This idealized model leads to the widely observed “fractional Stokes–Einstein (FSE) equation” (D∝(η/T)−ξ,0<ξ⩽1) relating the tracer particle diffusion coefficient D and the fluid viscosity η. The spherical obstruction model indicates the exponent value ξ=3/5, but ξ is predicted to vary somewhat with obstruction shape. Experimental values of ξ are summarized for comparison with our model.
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