Power law relationship between diffusion coefficients in multi-component glass forming liquids

TL;DR

This paper demonstrates that in multi-component glass-forming liquids, diffusion coefficients follow a power law relationship across various temperatures, aligning with the Adam-Gibbs relation and providing insights into their coupled dynamics.

Contribution

It reveals that diffusion coefficients in multi-component glass formers are related by a power law, extending the applicability of the Adam-Gibbs relation to multiple diffusion processes.

Findings

Diffusion coefficients follow a power law relationship in glass formers.

The power law holds across a wide temperature range.

The relation applies to various types of glass-forming liquids.

Abstract

The slow down of dynamics in glass forming liquids as the glass transition is approached has been characterised through the Adam-Gibbs relation, which relates relaxation time scales to the configurational entropy. The Adam-Gibbs relation cannot apply simultaneously to all relaxation times scales unless they are coupled, and exhibit closely related temperature dependences. The breakdown of the Stokes-Einstein relation presents an interesting situation to the contrary, and in analysing it, it has recently been shown that the Adam-Gibbs relation applies to diffusion coefficients rather than to viscosity or structural relaxation times related to the decay of density fluctuations. However, for multi-component liquids -- the typical cases considered in computer simulations, metallic glass formers, etc. -- such a statement raises the question of which diffusion coefficient is described by the Adam-Gibbs relation. All diffusion coefficients can be consistently described by the Adam-Gibbs relation if they bear a power law relationship with each other. Remarkably, we find that for a wide range of glass formers, and for a wide range of temperatures spanning the normal and the slow relaxation regimes, such a relationship holds. We briefly discuss possible rationalisations of the observed behaviour.