Crystallize

Crystallize refers to the formation of a crystalline solid with a regular lattice from a less ordered phase. It can occur from a supersaturated solution, a melt, or by deposition from a gas. The process involves nucleation, the initial appearance of a crystalline region, followed by growth as units join the lattice. Supersaturation, undercooling, and impurities influence the rate and outcome.

Practically, crystallization is achieved by methods such as evaporation or cooling of a saturated solution, adding an antisolvent, or solidification from a melt. Crystals can also form by gas deposition. Control of temperature, concentration, solvent, and agitation matters, as do the presence of seeds or surfaces that promote heterogeneous nucleation. Crystals may exhibit polymorphism, habit, and varying purity.

Applications span purification and isolation of compounds by recrystallization, production of pharmaceutical active ingredients, and creation of materials with defined properties in chemistry, metallurgy, and electronics. In the food industry, crystallization yields sugar or fat crystals. In geology and planetary science, crystal growth explains mineral formation and frost patterns.

Characterization relies on techniques such as X-ray diffraction to determine structure, microscopy to assess habit and defects, and melting point or thermal methods to assess purity. Challenges include controlling polymorphism, preventing aggregation, and preventing inclusion of impurities. Seeding and solvent choice are common strategies to steer crystal size and form.