Kinetics of the growth of domain blocks in KDP-type ferroelectric crystals

The process of the domain-block structure formation at the ferroelectric phase transition in KDP-type crystals is investigated. An effective Hamiltonian of the system is constructed; the growth of domain blocks in the vicinity of the Curie point is numerically simulated using the Monte Carlo method, and the temperature interval of the domain block growth is determined. It is shown that the asymptotic dependence of the mean block size on time has the form R(t) similar to root t/lnt. In the framework of an equivalent mathematical model combining the Ising and Kosterlitz-Thouless two-dimensional models, a kinetic equation that approximately describes the evolution of the domain-block size distribution function is derived.