Demixing of mixed oxide (A,B)O in an oxygen potential gradient: numerical solution of the time evolution of the demixing process

• Published in: Solid state ionics Vol. 123; no. 1; pp. 75 - 85
• Main Authors: Hong, J.-O., Teller, O., Martin, M., Yoo, H.-I.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1999; Elsevier Science
• Subjects: Chemical diffusion; Chemical interdiffusion; diffusion barriers; Condensed matter: structure, mechanical and thermal properties; Demixing; Diffusion in solids; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Oxide solid solution; Oxygen potential gradient; Physics; Solubility, segregation, and mixing; phase separation; Transport properties of condensed matter (nonelectronic); Oxide solid solution; Demixing; Chemical diffusion; Oxygen potential gradient; Oxides; Solid solutions; Diffusion; Experimental study; Demixtion
• ISSN: 0167-2738; 1872-7689
• DOI: 10.1016/S0167-2738(99)00105-8

The time evolution of the demixing process in a transition metal oxide solid solution, (A,B) 1− δ O, under a stationary oxygen potential gradient is calculated by solving the governing continuity equations numerically with a finite difference technique. The transient solution of the chemical diffusion process of a monoxide is also computed. From the time variations of the demixing profile and the spatial distribution of the chemical potential of oxygen in the oxide, it is found that two transient processes are involved in demixing leading to the steady state: (1) the establishment of a gradient in the chemical potential of oxygen across the system oxide; and (2) the redistribution of the cations leading to demixing.