High-frequency dynamics and test of the shoving model for the glass-forming ionic liquid Pyr14-TFSI
Artikel i vetenskaplig tidskrift, 2021

In studies of glass-forming liquids, one of the important questions is to understand to which degree chemically different classes of liquids have the same type of dynamics. In this context, room-temperature ionic liquids are interesting because they exhibit both van der Waals and Coulomb interactions. In this work we study the α relaxation and faster relaxation dynamics in the room-temperature ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14-TFSI). The paper presents quasielastic neutron and shear mechanical spectroscopy data measured over seven decades in frequency (10-3-104 Hz). The use of these two methods in combination reveal the α relaxation and four separate, faster modes. Two of these faster modes, based on the partial deuterations, can be assigned to the methyl group and the methyl end of the butyl chain of the cation. The neutron data are also used to determine the mean-square displacement (MSD) on the nanosecond timescale. It is shown that the temperature dependence of the MSD can account for the super-Arrhenius behavior of the α relaxation as predicted by the shoving model [Dyre, Rev. Mod. Phys. 78, 953 (2006)RMPHAT0034-686110.1103/RevModPhys.78.953], similarly to what is seen in simpler glass-forming liquids.


K. L. Eliasen

Roskilde Universitet (RUC)

Henriette Wase Hansen

Roskilde Universitet (RUC)

Institut Laue-Langevin

Chalmers, Fysik

Filippa Lundin

Chalmers, Fysik, Materialfysik

Daniel Rauber

Universität des Saarlandes

Rolf Hempelmann

Universität des Saarlandes

Tage Christensen

Roskilde Universitet (RUC)

Tina Hecksher

Roskilde Universitet (RUC)

Aleksandar Matic

Chalmers, Fysik, Materialfysik

Bernhard Frick

Institut Laue-Langevin

Kristine Niss

Roskilde Universitet (RUC)

Physical Review Materials

24759953 (eISSN)

Vol. 5 6 065606


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