Spinodal decomposition in tetragonal TiO2-SnO2 system

Abstract

A microscopic calculation was carried out for spinodal decomposition in the tetragonal TiO2‐SnO2 system by taking the contribution of the elastic free energy into account. Necessary elastic constants for the solid solutions and the elastic free energy of modulated structure were calculated in terms of interatomic potentials. Theoretical study and computer simulation were carried out for the dynamics of spinodal decomposition on the basis of a nonlinear diffusion equation derived from a coarse grained free energy. The time evolution of the microstructure and the effect of elastic strain on the decomposition process were investigated by Langer’s approximate method and the finite difference method. It was shown that the composition fluctuation along the [001] direction develops in the first stage, the formation of interface and the grain‐growth appear in the second stage, and the interface dislocations are introduced in the third stage. These results agree with the experimental observations in the tetragonal TiO2‐SnO2 system.