Fragile Glasses Associated with a Dramatic Drop of Entropy under Supercooling

Abstract

We perform kinetic Monte Carlo simulations of a distinguishable-particle lattice model of structural glasses with random particle interactions. By varying the interaction distribution and the average particle hopping energy barrier, we obtain an extraordinarily wide range of kinetic fragility. A stretching exponent, characterizing structural relaxation, is found to decrease with the kinetic fragility in agreement with experiments. The most fragile glasses are those exhibiting low hopping barriers and, more importantly, dramatic drops of entropies upon cooling toward the glass transition temperatures. The entropy drops reduce possible kinetic pathways and lead to dramatic slowdowns in the dynamics. In addition, the kinetic fragility is shown to correlate with a thermodynamic fragility.

arXiv commentMain text: 6 pages with 4 figures Supplementary: 11 pages with 18 figures

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• Kauzmann Paradox: a crossover due to diminishing local excitations
• Surface mobility gradient and emergent facilitation in glassy films
• The distinguishable-particle lattice model of glasses in three dimensions
• The Angell Plot from the Potential Energy Landscape Perspective