SCIPRESS FORMA
Forma, Vol. 1 (No. 1), pp. 9-39, 1985

Spatial and Temporal Macroscopic Structures in Chemical

Shoichi Kai* and Stefan C. Müller**

*Department of Electrical Engineering, Kyushu Institute of Technology
**Max-Planck-Institute für Ernährungsphysiologie

Keywords: pattern formation, nonequilibrium, nonlinear waves

Abstract. The phenomenon of macroscopic structure formation in time and space is presented for two chemical non-equilibrium systems: (1) patterning in precipitation processes and (2) motions at an oil-water interface. In the first case, stationary patterned deposition of a salt precipitate is observed which is referred to as (periodic) Liesegang rings in the presence of macroscopic concentration gradients and as non-periodic patterns in the absence of such gradients. Recent experimental results give support to the idea that a post-nucleation mechanism due to Ostwald ripening is mainly responsible for pattern formation. Secondly, experiments on the occurrence of macroscopic dynamical-time -patterns at the interface between two immiscible reactive solutions, related to a Marangoni type interfacial instability, are reported. Various types of non-linear wave motions are classified by establishing a detailed phase diagram in the solute concentration plane.