Scaling the alpha-relaxation time of supercooled fragile organic liquids

TL;DR

This paper demonstrates that the alpha-relaxation time in supercooled fragile liquids can be scaled using a single parameter combining density and temperature, extending previous findings to multiple materials.

Contribution

The authors extend the density-temperature scaling of alpha-relaxation time to various fragile liquids and propose a simple, universal functional form for tau(Gamma) with only three parameters.

Findings

Scaling applies to multiple fragile liquids.

A simple functional form for tau(Gamma) fits data over 12 orders of magnitude.

Experimental data cannot distinguish between different E(ro) forms.

Abstract

It was shown recently that the structural alpha-relaxation time tau of supercooled o-terphenyl depends on a single control parameter Gamma, which is the product of a function of density E(ro), by the inverse temperature T -1. We extend this finding to other fragile glassforming liquids using light-scattering data. Available experimental results do not allow to discriminate between several analytical forms of the function E(ro), the scaling arising from the separation of density and temperature in Gamma. We also propose a simple form for tau(Gamma), which depends only on three material-dependent parameters, reproducing relaxation times over 12 orders of magnitude.