Phase Transitions and Critical Phenomena

Abstract

Phase transitions may be classiˆed into several diƒerent types on the basis of the behavior with temperature of the thermodynamic potentials and the order parameter. e order parameter may change discontinuously or continuously at the transition point. In the thermodynamic description of phase transitions, the Helmholtz potential F (constant V) and the Gibbs potential G (constant P) play important roles. A scheme on the basis of the behavior of F or G in the vicinity of the transition point has been developed for the classiˆcation of phase transitions as continuous or discontinuous and is discussed in Section 9.3. Figure 9.1 shows a representative phase diagram in the P-T plane for a single component system.