How slow does a glass flow?

 Does the glass cease to flow at some finite temperature?” Answering this question––of pivotal importance for glass formation theories––would require ridiculously long observation times. We circumvent this infeasibility relating the (directly inaccessible) ultraviscous flow of a liquid to the elastic properties of the corresponding glass, which we measure as a function of its age. The older the glass, the lower the temperature at which viscosity can be determined. Taking advantage of physical vapor deposition, we rapidly obtain a wide spectrum of ages rivaling those of millenary ambers, enabling viscosity determinations at values as large as those pertaining to the asthenosphere. Our result, recently appeared in PNAS , ultimately rules out the finite-temperature divergence of the molecular diffusion timescale in a glass.

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Last Updated ( Friday, 31 July 2015 )