Crystallization is the process of forming a crystalline structure from a fluid or from materials dissolved in a fluid. It occurs in two main stages: the first step is known as nucleation, where particles form and grow, and the second step is known as crystal growth, which is the increase in particle size and leads to a crystalline state. Scientists often describe crystals as if they were growing even though they are not alive. In underground cavities, crystals grow through atoms that connect in regular three-dimensional patterns.
Each crystal starts small and grows as more atoms are added. Many grow in waters rich in dissolved minerals. However, this is not a requirement; crystals can also grow from molten rock or even from fumes. Under the influence of temperature and pressure, atoms combine to form an amazing variety of crystalline forms. It is this variety and perfection of form and symmetry that has attracted scientists to the study of minerals for centuries.
Crystallography is the science that measures the crystal structure (in other words, the atomic arrangement) of a crystal. For example, selenite crystals larger than 10 meters are found in the Cueva de los Cristales in Naica, Mexico. By tracking the speed and degree of change of particles and crystals in real time, the correct process parameters can be optimized for crystallization performance. Larger molecules can be difficult to crystallize at normal temperatures and pressures, although pure elements usually form a crystalline structure. For example, a perfect diamond crystal would only contain carbon atoms, but a real crystal could also contain some boron atoms. Crystallization is a process in which liquid materials solidify or become a solid or crystals, or it can be said that materials are rapidly removed from gas or liquid.
Other, less exotic crystallization methods can be used, depending on the physical properties of the substance, including hydrothermal synthesis, sublimation, or simply solvent-based crystallization. Crystal size distribution can be optimized and controlled by carefully choosing the right crystallization conditions and process parameters. You can often see the characteristic symmetry of a crystal with the naked eye, but if the crystal is very small, a magnifying glass or microscope is a convenient instrument. The choice of crystallization method depends on the equipment available for crystallization, the objectives of the crystallization process, and the solubility and stability of the solute in the chosen solvent. While the method chosen to crystallize the product may vary depending on several factors, there are six common steps for crystallization to occur. The fusion method excels in manufacturing polycrystals, but it can also grow single crystals using techniques such as crystal extraction, the Bridgman method and epitaxy.
It is a vital crystallization step because it determines the factors of the crystalline product, such as size distribution and phase. Solution concentration, supersaturation and crystalline form (polymorph) are usually related and largely determine the successful development of the crystallization process. Control over crystallizations is critical to achieving important quality attributes, and there are a significant number of interacting factors that influence crystallinity, crystal size, particle size distribution, polymorphism, and more. A crystal or crystalline solid is a solid material whose components, such as atoms, molecules or ions, are arranged in a highly ordered microscopic structure, forming a crystal network that extends in all directions.
