ABSTRACT
Phase transitions occur widely in nature and are part of everyday experience. The order parameter may change discontinuously or continuously at the transition point. Many phase transitions are found to be of first order, with a finite change in molar volume and with a latent heat of transition. The modern discussion and development of the subject of critical phenomena, which is concerned with the behavior of physical properties of systems that undergo continuous phase transitions, has, to a large extent, involved critical exponents. In the mid-twentieth century, Ginzburg and Landau developed a phenomenological approach that provides considerable insight into continuous phase transitions. This chapter has shown how the thermodynamic approach provides a means for classifying phase transitions on the basis of the behavior of the Helmholtz potential in the vicinity of the critical point.
