Nonequilibrium Thermodynamics of the Kovacs Effect

Details Nonequilibrium Thermodynamics of the Kovacs Effect Nonequilibrium Thermodynamics of the Kovacs Effect

2010-01-20

arxiv.org/abs/1001.3701v1

Physics

Condensed Matter

Materials Science

Scientific paper

We present a thermodynamic theory of the Kovacs effect based on the idea that the configurational degrees of freedom of a glass-forming material are driven out of equilibrium with the heat bath by irreversible thermal contraction and expansion. We assume that the slowly varying configurational subsystem, i.e. the part of the system that is described by inherent structures, is characterized by an effective temperature, and contains a volume-related internal variable. We examine mechanisms by which irreversible dynamics of the fast, kinetic-vibrational degrees of freedom can cause the entropy and the effective temperature of the configurational subsystem to increase during sufficiently rapid changes in the bath temperature. We then use this theory to interpret the numerical simulations by Mossa and Sciortino (MS), who observe the Kovacs effect in more detail than is feasible in laboratory experiments. Our analysis highlights two mechanisms for the equilibration of internal variables. In one of these, an internal variable first relaxes toward a state of quasi-equilibrium determined by the effective temperature, and then approaches true thermodynamic equilibrium as the effective temperature slowly relaxes toward the bath temperature. In the other mechanism, an internal variable directly equilibrates with the bath temperature on intermediate timescales, without equilibrating with the effective temperature at any stage. Both mechanisms appear to be essential for understanding the MS results.

Affiliated with

Also associated with

No associations

Rating

Nonequilibrium Thermodynamics of the Kovacs Effect does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Nonequilibrium Thermodynamics of the Kovacs Effect, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Nonequilibrium Thermodynamics of the Kovacs Effect will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-248622