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

Alejandro Sanz, Tina Hecksher, Henriette Wase Hansen, Jeppe Dyre, Kristine Niss, Ulf Rørbæk Pedersen

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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 densityscaling 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 pressuretemperature plane, both in the supercooled and the normal liquid regimes. We find that γ is generally statepoint
dependent, which is confirmed by reanalyzing data for 20 metallic liquids and two model liquids.
TidsskriftPhysical Review Letters
Udgave nummer5
StatusUdgivet - 8 feb. 2019

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