EXPERIMENTAL AND NUMERICAL MODELLING OF THE CRYSTAL GROWTH IN POROUS MEDIA. V.I. Rakin, Institute of Geology, Komi Sci. Cent. RASci, Syktyvkar

Crystallization experiments with calcium tartrate and calcium iodate in silica gels with holographic interference control showed that seed formation and crystal growth go through two stages which is supported by numerical modelling of crystal formation in gels by the method of difference equations. At the first stage, when substance is abundant, crystal growth is limited by surface processes (kinetically controlled regime). At the second stage, when substance is scarce, seed formation and crystal growth are limited by diffusion within the volume of the porous medium (diffusional regime). This regularity is most clearly demonstrated by the data on the rates of seed formation.

The numerical model involves parameters and conditions characteristic for the experiment with calcium iodate. The model deals with one-dimensional diffusion. Rates of seed formation and crystal growth is represented as a linear dependence. Nonlinearity is inherent in the law of substance diffusion. Only such nonlinearity is introduced in the model.

Certain conditions of the numerical experiment yielded structures similar to Liesegang bands which is also observed in the physical experiment.