Fragility and elastic behavior of a supercooled liquid

TL;DR

This paper presents a model for supercooled liquids that links their solid-like properties to long-time dynamics, revealing a linear relationship between fragility and the ratio of bulk to shear moduli.

Contribution

It introduces a coupled model of density fluctuations and local displacements in supercooled liquids, explaining the observed linear relation between fragility and elastic moduli ratio.

Findings

Model agrees with experimental observations of fragility and elastic moduli relation.

Shows coupling affects long-time dynamics in supercooled liquids.

Supports the idea of solid-like behavior influencing glass formation.

Abstract

A model for the supercooled liquid is considered by taking into account its solid like properties. We focus on how the long time dynamics is affected due to the coupling between the slowly decaying density fluctuations and the local displacement variables in the frozen liquid. Results from our model agree with the recent observation of Novikov and Sokolov [Nature (London) {\bf 431}, 961 (2004)] that the fragility index $m$ of a glass forming material is linearly related to the corresponding ratio $K/G$ of the bulk and the shear moduli.