Concepts in Kinetics in Solids

This chapter introduces the kinetic phenomena in materials. It presents concepts common to all kinetic phenomena in condensed matter. Kinetic phenomena that occur not too far from equilibrium conditions can be treated using linear approximations to rate relations. The linear realm including concepts from reaction rate theory and the thermodynamic theory of irreversible processes is discussed in this chapter. In gases, molecules come into contact by collision processes. In condensed matter, the atoms or molecules oscillate or rotate about a stable position or orientation, at any finite temperature. These oscillations or rotations make possible the existence of kinetic phenomena in condensed matter. Each such phenomenon involves the motions of atoms or molecules in some particular way, thus describing motion along a reaction path. If the energy of the system passes through a maximum as these particles move along the reaction path, then this maximum energy is referred as activation energy, which the system must exceed for it to precede from its initial state to a different state along this reaction path. Thus, the chapter considers a process taking place in a condensed phase in which reactants existing in some metastable state proceeds to a more stable product state.