ABSTRACT

Consider a crystal under the action of external influences (temperature, pressure, directional force fields). When any of these parameters is varied, the thermodynamic state of the crystal changes accordingly, tending to keep the free energy at the minimum value under all conditions. At certain specific values of the external parameters (or even internal parameters like composition), the crystal makes a transition to another phase with a lower free energy than the existing phase (cf. Fig. 1.1.1). We discuss phase transitions in this chapter.