Towards Relating Fragile-To-Strong Transition to Fragile Glass

TL;DR

This paper investigates the fragile-to-strong transition in glass formers using a lattice model, showing how narrowing energy dispersion induces the transition and aligns with observed relaxation behaviors.

Contribution

It demonstrates how adjusting energy distributions in a lattice model can reproduce the fragile-to-strong transition observed in real glasses.

Findings

FTS transition occurs when energy dispersion is narrowed.

Transition temperature coincides with minimum relaxation stretching exponent.

Model results agree with molecular dynamics simulations.

Abstract

Glass formers are in general classified as strong or fragile depending on whether their relaxation rates follow Arrhenius or super-Arrhenius temperature dependence. There are however notable exceptions such as water, which exhibit a fragile-to-strong (FTS) transition and behave as fragile and strong respectively at high and low temperatures. In this work, the FTS transition is studied using a distinguishable-particle lattice model previously demonstrated to be capable of simulating both strong and fragile glasses [Phys. Rev. Lett. 125, 265703 (2020)]. Starting with a bimodal pair-interaction distribution appropriate for fragile glasses, we show that by narrowing down the energy dispersion in the low-energy component of the distribution, a FTS transition is observed. The transition occurs at a temperature at which the stretching exponent of the relaxation is minimized, in agreement with previous molecular dynamics simulations.