**2.2 The "nucleation of the solid-phase" stage**

According to the Gibbs-Volmer thermodynamic theory, the formation of a new phase is possible with a certain critical degree of supersaturation, which depends both on the nature of the starting materials and on the presence of condensation nuclei that can be introduced into the system from the outside. The formation of nuclei becomes possible when a certain (critical) degree of supersaturation of a solution is reached by the substance whose molecules are involved in the formation of a new phase.

Thus, bearing in mind the possibilities of nanotechnological influence on the stage of particle nucleation, first of all, one should speak about such control factors as the creation of supersaturation and the introduction of condensation nuclei (nuclei) from outside. The supersaturation can be created in two ways: by increasing the concentration of the substance molecules in the medium and (or) by decreasing its solubility.
