Broadband dielectric spectroscopy and aging of glass formers

TL;DR

This study investigates aging effects in various glass formers using broadband dielectric spectroscopy, revealing that alpha-relaxation governs aging behavior across different dielectric quantities and spectral regions.

Contribution

It demonstrates that aging in glass formers is universally governed by alpha-relaxation, and provides a method to extract consistent relaxation parameters during aging.

Findings

Aging dependence is governed by alpha-relaxation regardless of dielectric quantity or spectral region.

Structural relaxation times during aging can be obtained consistent with equilibrium data.

Both structural and conductivity relaxation times are deduced from dielectric aging in CKN.

Abstract

We present the results of aging experiments on a variety of glass formers, including xylitol, glycerol, propylene carbonate, and [Ca(NO3)2]0.4[KNO3]0.6 (CKN). In addition, broadband dielectric spectra of xylitol and CKN are provided. We demonstrate that, irrespective of which dielectric quantities (dielectric constant, loss and modulus) are analyzed, and irrespective of the spectral region where they have been measured, the aging-time dependence always is governed by the structural rearrangements constituting the alpha-relaxation. If the time dependence of the structural relaxation time during aging is taken into account, relaxation times and stretching parameters, fully consistent with equilibrium data, are obtained. In CKN, both the structural relaxation time and the strongly decoupled conductivity relaxation time are deduced from the same dielectric aging experiment.