Crystallization and polymorphism - Description of the phenomenon

After a brief historical review, this first article examines in detail the various definitions concerning crystalline polymorphism and the amorphous state, as well as those concerning powder particles (habitus/facies, aggregation and agglomeration states). Crystalline polymorphism and facies are the consequence of a complex process known as crystallization, for which a brief introduction is given in the case of the crystallization of a molecule from a solvent. This highlights the various physico-chemical parameters that play a key role in this phenomenon (nucleation, activation energy of nucleation, role of solvent and impurities, etc.). Finally, in the last paragraph, a reminder of the elements of crystallography (crystal systems/Bravais lattices, crystal lattice, asymmetric unit) is given, with the aim of establishing a number of definitions necessary for the overall understanding of the three articles that make up this study.