Theory of spinodal decomposition in magnetic liquids. The intermediate stage

The spinodal decomposition is a peculiar, insufficiently explored phase transition stage of the first kind, in which the separating system is in an absolute thermodynamically unstable state. The complete spinodal decomposition theory has yet to be formulated. In the present report a relatively simple model is presented for the spinodal decomposition of a ferrocolloid in an external magnetic field, which takes into account the interaction of concentration fluctuations. This model is not intended to describe all stages of this process and, in particular, the period when a significant portion of the colloids have changes into the large- and low-concentration metastable states, in which, according to the usual scenario of phase transitions of the first kind, heterogeneous nuclei of new phases appear. The assumed model approximately describes the intermediate separation stage which follows immediately after the linear. 17 refs., 2 figs