Nucleation: what happens at the initial stage?

Crystallizing growth: The initial structure of crystal nuclei is supersaturation-dependent. At low degrees of supersaturation, liquid-like nuclei are formed initially, which undergo a continuous structure transition from liquid-like to crystal-like as the size N increases. This gradual structure evolution substantially lowers the nucleation barrier DeltaG* and facilitates the nucleation relative to the formation of crystal-like clusters from the beginning.