Abstract: Based on the thermodynamic and kinetic analyses of Schlogl model in nonideal condition, the dependent relation between chemical stability and diffusion stability is studied. It is found that, under the conditions that the system is far from chemical equilibrium and is strongly nonideal, both excess entropy δ~2S and its time-derivative for some space-uniform steady state may, independently to a certain extent, be positive or negative. Thus the chemical reactions and diffusion may show same or different stabilities in both cases that diffusion is stable and unstable. The linear stability analysis of kinetic equation for Schlögl model has confirmed this Clansdorff-Prigogine theory of nonequilibrium thermodynamic stability which concerns itself mainly about the chemical stability in diffusionstable systems.
When system is diffusion-unstable but chemically stable, their competition might give rise to the formation of some ordered structures (dissipative structures), as it does when system is diffusion-stable but chemically unstable. The numerical simulations have confirmed this prediction. Since the phenomena of diffusion instability are rather common in practical systems, such consideration of formation of ordered structures through the competition between chemical stability and diffusion instability may expand the applications of the theory of dissipative structures.