Dynamics of simultaneous ordering and phase separation and effect of long-range Coulomb interactions

The dynamics of simultaneous ordering and phase separation in the presence of a long-range Coulomb interaction is investigated by a computer simulation. It is shown that an intermediate nonstoichiometric ordered single phase appears as a transient phase during decomposition of a binary homogeneous disordered solid solution into an equilibrium two-phase mixture of ordered and disordered phases. Introduction of the long-range Coulomb interactions results in a mesoscale phase which consists of periodical arrays of ordered phase particles embedded in a disordered matrix.