Tracking coupled granular temperature and configurational entropy dynamics in granular materials via dielectric spectroscopy
Year: 2026
Type: article
Abstract: In glass-forming liquids, structural dynamics are closely related to configurational entropy and temperature, with dielectric relaxation time scaling alongside structural relaxation time as described by the Adam-Gibbs (AG) model. Under Edwards’s athermal statistical thermodynamics, a modified AG relationship has been proposed for granular matter, provided that granular temperature and configurational entropy are appropriately defined. This study investigates whether the electrical response of granular systems can provide insight into their structural dynamics through thermally activated processes, specifically electric charge hopping and trapping. By progressively reducing the volume of graphite powder to vary its packing fraction, we estimated relative configurational entropy and granular temperature from volumetric data, while evaluating electrical conductivity and capacitance via impedance spectroscopy. We demonstrate that the logarithm of the dielectric relaxation time, derived from complex impedance, exhibits a scaling behavior with granular temperature and configurational entropy across both loose and compact states. Consequently, changes in the complex impedance resulting from packing fraction variations are tuned by granular configuration, consistent with an AG-like relationship for thermal systems. These findings establish dielectric spectroscopy as a viable, non-destructive tool for tracing configurational dynamics in granular matter, analogous to its established use in polymers and glass-forming liquids.
Source: Transport Phenomena
DOI: 10.1515/tp-2026-0107
Institution: National and Kapodistrian University of Athens
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7221055562