| Autor: |
Li Y; School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA., Annamareddy A; Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Morgan D; Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Yu Z; Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Wang B; Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Cao C; Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Perepezko JH; Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Ediger MD; Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Voyles PM; Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA., Yu L; School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA.; Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA. |
| Abstrakt: |
Surface diffusion is vastly faster than bulk diffusion in some glasses, but only moderately enhanced in others. We show that this variation is closely linked to bulk fragility, a common measure of how quickly dynamics is excited when a glass is heated to become a liquid. In fragile molecular glasses, surface diffusion can be a factor of 10^{8} faster than bulk diffusion at the glass transition temperature, while in the strong system SiO_{2}, the enhancement is a factor of 10. Between these two extremes lie systems of intermediate fragility, including metallic glasses and amorphous selenium and silicon. This indicates that stronger liquids have greater resistance to dynamic excitation from bulk to surface and enables prediction of surface diffusion, surface crystallization, and formation of stable glasses by vapor deposition. |
