Low Temperature Physics: 24, 20 (1998); https://doi.org/10.1063/1.593530 (15 pages)
Fizika Nizkikh Temperatur: Volume 24, Number 1 (January 1998), p. 27-46    ( to contents , go back )

On thermodynamics of supercooled liquids and glasses

A. S. Bakai

National Scientific Center " Physico-Tekhnical Insititute ", 1 Academicheskaya st., Kharkov 310108, Ukraine
E-mail: bakai@kipt.kharkov.ua
pos Анотація:

(Submitted June 18, 1997, revised August 7, 1997)

Abstract

Theomodynamics of glass-forming liquids and glasses is considered taking into account the contributions of heterophase fluctuations to free energy. The heterophase fluctuations in liquids are nuclei of non-crystalline solids. In glass the heterophase fluctuations are nuclei of liquid. The crystalline solid state is not considered. The droplet approach and the mixed state model are applied to describe free energy. It is shown that there exist three regions of stability of different structure states of the system in the plane (P ,T ) . Two of them are the stability regions of the droplet structure states. In the third one the mixed state is stable. In the droplet states the heterophase fluctuations exist as isolated droplets. In the mixed state two infinite percolating clusters (solid and liquid) are coexisting. The widths of the temperature interval, [Tt1,Tt2], where the mixed state is stable increase with the growth of the configurational entropy (complexity) of the non-crystalline solid fraction. In the frame of the approach used weak 1st order phase transitions are revealed at T=Tt1 and T=Tt2. It is shown that in the mixed state the 1st order or 2nd order phase transitions are possible. The criteria of these phase, transitions are obtained. Equations of state and expressions of thermodynamic quantities (entropy, specific heat capacity, compressibility and thermal expansion coefficient) in the droplet and mixed states are derived.

PACS:
64.70.Dv - Solid-liquid transitions

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