Computer Simulation of Kinetics of Spinodal Decomposition in the Tetragonal TiO2–SnO2 System

Computer simulation was carried out for the kinetics of spinodal decomposition in the tetragonal TiO₂–SnO₂ system on the basis of a nonlinear diffusion equation. A time evolution of the microstructure and the effect of coherent strain on the separated two phases were investigated by Langer's approximate method and the finite difference method. It was shown that the composition fluctuations develop in the first stage of the spinodal decomposition, and the formation of interface and the grain growth appear in the second stage. The local stress field and the local strain field with the coherence of the lattice were calculated. Subsequently the appearance of the interface dislocations in the (100) and (010) planes was demonstrated to occur in the third stage. Physical interpretation was given to the experimental observations for the tetragonal TiO₂–SnO₂ system on the basis of those calculations.