Qualitative change in structural dynamics of some glass-forming systems

TL;DR

This paper investigates the temperature dependence of structural relaxation in glass-forming liquids, revealing a qualitative change that challenges previous assumptions about divergence at low temperatures.

Contribution

It identifies a cusp-like maximum in the second derivative of the relaxation time, indicating a crossover from super-Arrhenius to Arrhenius behavior and questioning the divergence at finite temperatures.

Findings

Maximum in second derivative of log relaxation time observed

Crossover from super-Arrhenius to Arrhenius behavior identified

No divergence of relaxation time at non-zero temperature

Abstract

Analysis of temperature dependence of structural relaxation time in supercooled liquids revealed a qualitatively distinct feature - a sharp, cusp-like maxumum in the second derivative of its logarithm. It suggests that the super-Arrhenius behavior of the structural relaxation time in glass-forming liquids eventually crosses over to the Arrhenius behavior below the temperature of maximum, and there is no divergence of the relaxation time at non-zero temperature. The position of the maximum can be both above or below glass transition temperature, depending on the sensitivity of the structural relaxation time to changes in density. These results might turn the discussion of the glass transition to the new avenue - the origin of the limiting activation energy for structural relaxation at low temperatures.