Experimental Evidence for a State-Point-Dependent Density-Scaling Exponent of Liquid Dynamics

A large class of liquids obey density scaling characterized by an exponent, which quantifies the relative roles of temperature and density for the dynamics. We present experimental evidence that the density-scaling exponent γ is state-point dependent for the glass formers tetramethyl-tetraphenyl-tri...

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Bibliographic Details
Published in:Physical review letters 2019-02, Vol.122 (5), p.055501-055501, Article 055501
Main Authors: Sanz, Alejandro, Hecksher, Tina, Hansen, Henriette Wase, Dyre, Jeppe C, Niss, Kristine, Pedersen, Ulf R
Format: Article
Language:English
Subjects:
Density
Liquids
Polyphenyl ether
Scaling
Thermodynamic equilibrium
Thermodynamic properties
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Summary:A large class of liquids obey density scaling characterized by an exponent, which quantifies the relative roles of temperature and density for the dynamics. We present experimental evidence that the density-scaling exponent γ is state-point dependent for the glass formers tetramethyl-tetraphenyl-trisiloxane (DC704) and 5-polyphenyl ether (5PPE). A method is proposed that from dynamic and thermodynamic properties at equilibrium estimates the value of γ. The method applies at any state point of the pressure-temperature plane, both in the supercooled and the normal liquid regimes. We find that γ is generally state-point dependent, which is confirmed by reanalyzing data for 20 metallic liquids and two model liquids.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.122.055501