Paraelastic—ferroelastic interfaces

Paraelastic–ferroelastic phase boundaries (interfaces) are two-dimensional formations in the three-dimensional crystal lattice, which accommodate the crystal lattices of two neighbouring modifications of the same compound. Their characteristic features include both orientation and kinetic properties. Three theories are presented describing the orientation of phase boundaries, i.e. the modified Sapriel theory, the Metrat theory and the Roitburd theory. The most useful of these three is the Roitburd theory. Relatively little attention has been paid to the kinetics of phase boundaries in ferroelastics. An interesting attempt made by Gordon to describe the phase boundaries' kinetics in terms of solitary wave theory is presented. The kink type solution of the time dependent Ginzburg-Landau equation may be identified with a moving phase boundary.