Scaling of broadband dielectric data of glass-forming liquids and plastic crystals

TL;DR

This study evaluates scaling procedures for broadband dielectric data of glass-forming liquids and plastic crystals, revealing deviations at high frequencies and questioning the divergence of static susceptibility near the Vogel-Fulcher temperature.

Contribution

It applies and compares Nagel and Dendzik scaling methods to broadband dielectric data, extending analysis range and examining susceptibility divergence.

Findings

Deviations from master curves at high frequencies.

Plastic crystals do not scale in Nagel-plot but do in Dendzik-plot.

No evidence of divergence of static susceptibility near Vogel-Fulcher temperature.

Abstract

The Nagel-scaling and the modified scaling procedure proposed recently by Dendzik et al. have been applied to broadband dielectric data on two glass- forming liquids (glycerol and propylene carbonate) and three plastic crystals (ortho-carborane, meta-carborane, and 1-cyano-adamantane). Our data extend the upper limit of the abscissa range to considerably higher values than in previously published analyses. At the highest frequencies investigated, deviations from a single master curve show up which are most pronounced in the Dendzik-scaling plot. The loss curves of the plastic crystals do not scale in the Nagel-plot, but they fall onto a separate master curve in the Dendzik-plot. In addition, we address the question of a possible divergence of the static susceptibility near the Vogel-Fulcher temperature. For this purpose, the low-temperature evolution of the high-frequency wing of the dielectric loss peaks is investigated in detail. No convincing proof for such a divergence can be deduced from the present broadband data.