Formation of nanoparticles of bi-metallic catalysts for the growth of carbon nanotubes

Abstract

The process of phase transformation in a bi-metallic submonolayer film is studied based on phase-field theory. The film is considered as a quasi-ternary system, which is characterized by the various distribution of phases depending on the temperature and composition. The dynamics of the phase transformation are analyzed by the modified Cahn–Hilliard equation taking into account degenerative mobility, and the colored noise corresponding to compositional fluctuations, deposition, and evaporation of atoms. In most cases, the later stage of the phase transformation in a pre-deposited two-component film exhibits the power-law dependence of the linear size of new phases R ∼ t^1/4 both for the nucleation and spinodal decomposition mechanism. We have analyzed different regimes of the phase transformation in two-component submonolayer films during physical vapor deposition that can be useful for the determination of optimal conditions of the synthesis of the submonolayer films with the required morphology.