Universal correlations between the fragility and interparticle repulsion of glass-forming liquids

TL;DR

This paper applies an analytical model linking microscopic interparticle potential parameters to the fragility of glass-forming liquids, demonstrating universal correlations across diverse nonmetallic systems.

Contribution

It extends a model originally for metallic melts to nonmetallic glasses, establishing a universal link between interparticle repulsion and fragility.

Findings

Correlation between lambda and fragility parameter m.

Model accurately fits viscosity and relaxation times across systems.

Fragility can be traced to microscopic interaction parameters.

Abstract

A recently published analytical model, describing and predicting elasticity, viscosity, and fragility of metallic melts, is applied for the analysis of about 30 nonmetallic glassy systems, ranging from oxide network glasses to alcohols, low-molecular-weight liquids, polymers, plastic crystals, and even ionic glass formers. The model is based on the power-law exponent lambda representing the steepness parameter of the repulsive part of the inter-atomic or -molecular potential and the thermal-expansion parameter alpha_T determined by the attractive anharmonic part of the effective interaction. It allows fitting the typical super-Arrhenius temperature variation of the viscosity or dielectric relaxation time for various classes of glass-forming matter, over many decades. We discuss the relation of the model parameters found for all these different glass-forming systems to the fragility parameter m and detect a correlation of lambda and m for the non-metallic glass formers, in accord with the model predictions. Within the framework of this model, thus the fragility of glass formers can be traced back to microscopic model parameters characterizing the intermolecular interactions.