3. Kinetics of pressure-induced phase transitions

Historically, the classification of phase transitions has been based either on the rate of transformation or on the nature of the crystalline forms encountered (Ehrenfest). For pressure-induced phase transformations, it is perhaps more general to consider two categories of solid-solid transition :

• displacive polymorphic transformations, for which the activation energy is relatively low and the transformation rather rapid. They occur at relatively low temperatures (ambient or...