Kinetics of order-disorder phase transitions for non-uniform order parameters

Abstract

Phenomenological theories of phase transition kinetics are extended towards initially nonuniform order parameters in the order-disorder limit. The resulting equations predict slowing down of the order parameter kinetics close to the equilibrium state and at low temperatures, T ≫ T _c. The extent of the deviations from standard TDGL behaviour depends on the value of the mixing coefficient ε² _c/ε², which regulates the stability of quenched order parameter fluctuations. Large values of ε² _c/ε² result in the development of locally saturated order parameters Q(r) in the non-equilibrium state. If the range of interactions falls below the coarse graining length, a transient overshooting of the order parameter above its equilibrium value is predicted.

Key Words:

• Keywords: Mixed kinetics
• Order-disorder
• Cation ordering
• Overshooting
• Fluctuations
• Phase transitions