Two Inherent Crossovers of the Diffusion Process in Glass-Forming Liquids

Published

October 5, 2018

Author(s)

Maiko Kofu, Antonio Faraone, Madhu Sudan Tyagi, Michihiro Nagao, Osamu Yamamuro

Abstract

We report on incoherent quasielastic neutron scattering measurements examining a self-diffusion process in two types of glass-forming liquids, a molecular liquid (3-methylpentane) and an ionic liquid (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide). We have experimentally demonstrated that both liquids exhibit two crossovers in the momentum transfer (Q) dependence of the self-correlation function which is basically described by the stretched exponential function, exp[-(t/T)^β]. The first crossover point (Q approximately equal} 0.2 angstrom}^-1) corresponds to a crossover from Fickian (βequal with a line 1) diffusion attributed to dynamical correlation. On the other hand, the second one at Q=0.8angstrom}^-1 is associated with the crossover from the Gaussian to non-Gaussian behavior. It is remarkable that the stretching exponent β gradually changes in between the two crossover points. We consider that the two crossovers are the universal feature for glass-forming liquids.

Citation

Physical Review E

Volume

98

Issue

4

Pub Type

Journals

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Keywords

glass formers, crossover, neutron scattering

Citation

Kofu, M. , Faraone, A. , Tyagi, M. , Nagao, M. and Yamamuro, O. (2018), Two Inherent Crossovers of the Diffusion Process in Glass-Forming Liquids, Physical Review E, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=926866 (Accessed October 21, 2025)