MODELING OF INTERDIFFUSION AND PHASE FORMATION IN THE THIN-FILM TWO-LAYER SYSTEM OF POLYCRYSTALLINE OXIDES TITANIUM AND COBALT

Abstract

Purpose. A model of reactive interdiffusion in a bilayer system of polycrystalline oxides of two metals with moving and stationary components in each phase is proposed. The model develops Darken theory of interdiffusion in a binary system with unlimited solubility. Results. The model provides for the existence of an immobilized metal in two states – in the composition of the traps of its phase and in the form of the oxide of another metal trapped in the trap in the phase. The interdiffusion of the mobile component of metals into phases of neighboring oxides with subsequent capture to trap centers serves as the basis for the formation of phases of complex oxides. The formulation of the boundary-value problem of the model is considered. Conclusions. Within the framework of the model, a numerical analysis of the experimental concentration distributions of titanium and cobalt in the TiO2–x – Co1–уO thin-fi lm system obtained by the Rutherford backscattering method was performed. The analysis revealed the dominant role of the diffusion of mobile cobalt into the TiO2–x phase compared with the diffusion of mobile titanium into the Co1–уO phase and the region of localization of the formation of complex oxide phases in the vicinity of the TiO2–x–Co1–у O interface.

Keywords

• modeling
• reaction interdiffusion
• Kirkendall effect
• interphase boundaries
• polycrystalline fi lms
• complex oxides.