Computer simulation of domain formation in the order-disorder phase transition of the KSCN model.

Abstract

The tetragonal-orthorhombic improper ferroelastic phase transition and domain formation of the order-disorder KSCN model is studied by molecular-dynamics simulation. A two-dimensional model of either 105\ifmmode\times\else\texttimes\fi{}105 or 49\ifmmode\times\else\texttimes\fi{}49 unit cells represents a layer of this crystal. The simulation determines the orientational and strain order parameters and transition temperature. The mean-field theory gives excellent qualitative agreement of the calculated and simulated phase transition temperature. On quenching from the disorder phase and subsequent annealing, a tweed texture is obtained, which later evolves to a stripe phase with well oriented ferroelastic domain walls and arbitrarily oriented antiphase boundaries.