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Crystallization is the process by which solids form, where the atoms or molecules are highly organized into a structure known as a crystal. Some ways by which crystals form are precipitating from a solution, freezing, or more rarely deposition directly from a gas.
For other solvents of crystallization, analysis is conveniently accomplished by dissolving the sample in a deuterated solvent and analyzing the sample for solvent signals by NMR spectroscopy. Single crystal X-ray crystallography is often able to detect the presence of these solvents of crystallization as well. Other methods may be currently ...
In chemistry, fractional crystallization is a stage-wise separation technique that relies on the liquid–solid phase change. This technique fractionates via differences in crystallization temperature and enables the purification of multi-component mixtures, as long as none of the constituents can act as solvents to the others. Due to the high ...
Crystal growth is a major stage of a crystallization process, and consists of the addition of new atoms, ions, or polymer strings into the characteristic arrangement of the crystalline lattice. [ 1 ] [ 2 ] The growth typically follows an initial stage of either homogeneous or heterogeneous (surface catalyzed) nucleation , unless a "seed ...
These have been compared with the classical theory, for example for the case of nucleation of the crystal phase in the model of hard spheres. This is a model of perfectly hard spheres in thermal motion, and is a simple model of some colloids. For the crystallization of hard spheres the classical theory is a very reasonable approximate theory. [9]
Crystallography ranges from the fundamentals of crystal structure to the mathematics of crystal geometry, including those that are not periodic or quasicrystals. At the atomic scale it can involve the use of X-ray diffraction to produce experimental data that the tools of X-ray crystallography can convert into detailed positions of atoms, and ...
The above mechanism considered crystallization from the melt, which is important for injection molding of plastic components. Another type of crystallization occurs upon extrusion used in making fibers and films. In this process, the polymer is forced through, e.g., a nozzle that creates tensile stress which partially aligns its molecules. Such ...
A crystal's crystallographic forms are sets of possible faces of the crystal that are related by one of the symmetries of the crystal. For example, crystals of galena often take the shape of cubes, and the six faces of the cube belong to a crystallographic form that displays one of the symmetries of the isometric crystal system. Galena also ...