Thermodynamics of Equilibrium on the "Crystal–Vapor" Interface
The topological analysis of the "crystal-vapor" equilibrium fragment of phase diagram of single-component substance is carried out. We proposed the model of the "crystal-vapor" equilibrium that enabled to obtain analytical expressions for temperature dependence of the saturated vapor pressure of the sublimated substance. Quantitative regularities governing the influence of polycrystalline substance dispersion are studied with account of polymorphism. Analytical expressions of coupling between form and size of microcrystals of polymorphic solid phase are obtained. Size dependences for pressure of isothermal transformations and for temperature of isobaric transformations of a polycrystalline substance are found. Analytical generalization of the empiric Ostwald "rule of the stages" is offered. Thermodynamical pre-condition for plastic-crystalline mesomorphism of organic compounds is substantiated.