A seed crystal is a small piece of
single crystal or
polycrystal material from which a large
crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...
of typically the same material is grown in a laboratory. Used to replicate material, the use of seed crystal to promote growth avoids the otherwise slow randomness of natural crystal growth and allows manufacture on a scale suitable for industry.
Crystal enlargement
The large crystal can be
grown by dipping the seed into a
supersaturated solution, into molten material that is then cooled, or by growth on the seed face by passing vapor of the material to be grown over it.
Theory
The theory behind this effect is thought to derive from the physical intermolecular interaction that occurs between compounds in a supersaturated
solution
Solution may refer to:
* Solution (chemistry), a mixture where one substance is dissolved in another
* Solution (equation), in mathematics
** Numerical solution, in numerical analysis, approximate solutions within specified error bounds
* Solutio ...
(or possibly vapor). In solution, liberated (soluble) molecules (
solute) are free to move about in random flow. This random flow permits for the possibility of two or more molecular compounds to interact. This interaction can potentiate intermolecular forces between the separate molecules and form a basis for a
crystal lattice
In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by
: \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n ...
. The placement of a seed crystal into solution allows the
recrystallization process to expedite by eliminating the need for random molecular collision or interaction. By introducing an already pre-formed basis of the target crystal to act upon, the intermolecular interactions are formed much more easily or readily, than relying on random flow. Often, this phase transition from solute in a solution to a
crystal lattice
In geometry and crystallography, a Bravais lattice, named after , is an infinite array of discrete points generated by a set of discrete translation operations described in three dimensional space by
: \mathbf = n_1 \mathbf_1 + n_2 \mathbf_2 + n ...
will be referred to as
nucleation. Seeding is therefore said to decrease the necessary amount of time needed for nucleation to occur in a recrystallization process.
Uses
One example where a seed crystal is used to grow large
boules or
ingots of a single crystal is the
semiconductor
A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way ...
industry where methods such as the
Czochralski process or
Bridgman technique Bridgman is a surname, and may refer to:
* David Bridgman, Australian architect
* Elijah Coleman Bridgman (1801–1861), American missionary in China
* Frederick Arthur Bridgman (1847-1928), American artist
* George Bridgman (1865-1943), anatomis ...
are employed.
Also during the process of
tempering chocolate, seed crystals can be used to promote the growth of favorable type V crystals
See also
*
Crystal structure
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pattern ...
*
Crystallization
Crystallization is the process by which solid forms, 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 deposi ...
*
Laser heated pedestal growth
*
Micro-pulling-down
*
Polycrystal
*
Single crystal
*
Wafer (electronics)
In electronics, a wafer (also called a slice or substrate) is a thin slice of semiconductor, such as a crystalline silicon (c-Si), used for the fabrication of integrated circuits and, in photovoltaics, to manufacture solar cells. The wafer ser ...
*
Disappearing polymorphs
References
Crystals
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