Transitions between Equilibrium and Nonequilibrium Phenomena in the Description of Crystal Growth

The close intertwining of equilibrium and nonequilibrium thermodynamic representations and transitions between two limiting principles of thermodynamics: the second beginning and the principle of least coercion (minimum entropy production in the stationary regime) constitute the main content of the phenomenological theories of crystal growth. The difference of the basic postulates of two sections of thermodynamics forces to discuss the problems of reversibility and irreversibility of time, scales of observed phenomena, and rules of conjugation of thermodynamic forces and flows in theories of crystal growth. A variant of the solution of some conjugation problems is shown on the example of the fluctuation model of dislocation crystal growth, which is based on the stationary isothermal process of thermodynamic free energy fluctuations. In the case of the limiting mode of adsorption of impurities on the crystal face according to the Langmuir model, the free-energy fluctuations characterized by the absence of the memory effect make it possible to identify three chemical potentials of building particles, which determine the corresponding values of solution supersaturations realized at different scale levels at the growing crystal face containing a screw dislocation. The supersaturations control quasi-equilibrium and nonequilibrium thermodynamic processes that constitute a unified dislocation mechanism of crystal growth.