Introduction

Abstract

Phase transitions are significant changes in the system’s properties and symmetry, which happen as a result of changes of the external conditions (temperature, pressure, chemical potential, etc.). Although various phase transitions are discussed in the book as physical phenomena, the book is more about the method to study the phase transitions than about the phenomena themselves. A lot has been written about behavior of a system close to the critical point; it is characterized by special features such as scale invariance. However, these are rare cases and most of the systems spend most of their time far away from the critical points. Rephrasing Feynman we can say that there is plenty of room away from the critical point. Evolutions of the systems when they are not close to the critical points are characterized by completely different physical features, such as rate of nucleation and growth, microstructure or pattern formation, structure modification and coarsening, etc. Physical descriptions of these features require that special consideration is taken to the free energies of the phases involved in the transformations, which in many cases are known either from thermodynamic calculations or direct experimental measurements. All of that sets the stage for different approach to phase transitions, more phenomenological, which is the main subject of this book.