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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.
In some cases, the degree of hydration can be critical to the resulting chemical properties. For example, anhydrous RhCl 3 is not soluble in water and is relatively useless in organometallic chemistry whereas RhCl 3 ·3H 2 O is versatile. Similarly, hydrated AlCl 3 is a poor Lewis acid and thus inactive as a catalyst for Friedel-Crafts reactions.
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 ...
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 ...
Liquid crystal (LC) is a state of matter whose properties are between those of conventional liquids and those of solid crystals.For example, a liquid crystal can flow like a liquid, but its molecules may be oriented in a common direction as in a solid.
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 ...
Vectors and planes in a crystal lattice are described by the three-value Miller index notation. This syntax uses the indices h, k, and ℓ as directional parameters. [4] By definition, the syntax (hkℓ) denotes a plane that intercepts the three points a 1 /h, a 2 /k, and a 3 /ℓ, or some multiple thereof. That is, the Miller indices are ...
Crystal formation requires two steps: nucleation and growth. [3] Nucleation is the initiation step for crystallization. [3] At the nucleation phase, protein molecules in solution come together as aggregates to form a stable solid nucleus. [3] As the nucleus forms, the crystal grows bigger and bigger by molecules attaching to this stable nucleus ...