iPedia Free Information Center

Information about Monocrystal

Enlarge picture
A huge KDP crystal grown from a seed crystal in a supersaturated aqueous solution at LLNL which is to be cut into slices and used on the National Ignition Facility for frequency doubling and tripling.


A single crystal, also called monocrystal, is a crystalline solid in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample, with no grain boundaries. The opposite of a single crystal sample is a polycrystalline sample, which is made up of a number of smaller crystals known as crystallites. Because of a variety of entropic effects on the microstructure of solids, including the distorting effects of impurities and the mobility of crystallographic defects and dislocations, single crystals of meaningful size are exceedingly rare in nature, and can also be difficult to produce in the laboratory under controlled conditions (see also recrystallisation).

Because grain boundaries can have significant effects on the physical and electrical properties of a material, single crystals are of interest to industry, and have important industrial applications. The most notable of these is the use of single crystal silicon in the fabrication of semiconductors. On the quantum scale that microprocessors operate on, the presence of grain boundaries would have a significant impact on the functionality of field effect transistors by altering local electrical properties. Therefore, microprocessor fabricators have invested heavily in facilities to produce large single crystals of silicon.

Fabrication of single crystals usually involves the building of a crystal layer by layer of atoms. Techniques to produce large single crystals (boules) include slowly drawing a rotating "seed crystal" in a molten bath of feeder material (as in the Czochralski process and the Bridgeman technique). Some thin film deposition techniques can be used for epitaxy, forming a new layer of material with the same structure on the surface of an existing single crystal.

Uses

Monocrystals of silicon and other semiconductors are important for manufacture of integrated circuits.

Monocrystals of sapphire and other materials are used for lasers and nonlinear optics.

Monocrystals of fluorite are sometimes used in the objective lenses of apochromatic refracting telescopes.

Monocrystals of metals, especially superalloys, are used for their special mechanical properties. Turbine blades of some gas turbines are made of single crystal cast superalloy.

Monocrystals of copper (crystalline copper) are used for fine crystalline powders and hi tech wires.

See Also

References

CRYSTAL is a quantum chemistry ab initio program, designed primarily for calculations on crystals (3 dimensions), slabs (2 dimensions) and polymers (1 dimension) using translational symmetry, but it can be used for single molecules.[1] It is written by V.R. Saunders, R.
..... Click the link for more information.
A solid object is in the states of matter characterized by resistance to deformation and changes of volume. At the microscopic scale, a solid has these properties :
  • The atoms or molecules that comprise the solid are packed closely together.

..... Click the link for more information.
crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a motif, a set of atoms arranged in a particular way, and a lattice. Motifs are located upon the points of a lattice, which is an array of points repeating periodically in three
..... Click the link for more information.
crystallite is a domain of solid-state matter that has the same structure as a single crystal. Metallurgists often refer to crystallites as "grains".

Solid objects that are large enough to see and handle are rarely composed of a single crystal, except for a few cases
..... Click the link for more information.
polycrystal is a material that is made of many smaller crystallites with varying orientation. The variation in direction can be random (called random texture) or directed, possibly due to growth and processing conditions. Fiber texture is an example of the latter.

Cf.
..... Click the link for more information.
crystallite is a domain of solid-state matter that has the same structure as a single crystal. Metallurgists often refer to crystallites as "grains".

Solid objects that are large enough to see and handle are rarely composed of a single crystal, except for a few cases
..... Click the link for more information.
Ice melting - a classic example of entropy increasing[1] described in 1862 by Rudolf Clausius as an increase in the disgregation of the molecules of the body of ice.
..... Click the link for more information.
Impurities are substances inside a confined amount of liquid, gas, or solid, which differ from the chemical composition of the material or compound.

Impurities are either naturally occurring or added during synthesis of a chemical or commercial product.
..... Click the link for more information.
crystal defects. The various types of defects are enumerated here.

Point defects

It has been suggested that this section be split into a new article. ()
Point defects are defects which are not extended in space in any dimension.
..... Click the link for more information.
dislocation is a crystallographic defect, or irregularity, within a crystal structure. The presence of dislocations strongly influences many of the properties of real materials. The theory was originally developed by Vito Volterra in 1905.
..... Click the link for more information.
Recrystallization (see also crystallization) is an essentially physical process that has meanings in chemistry, metallurgy and geology.

Chemistry

In chemistry, recrystallization is a procedure for purifying compounds.
..... Click the link for more information.
grain boundary is the interface between two grains in a polycrystalline material. Grain boundaries disrupt the motion of dislocations through a material so reducing crystallite size is a common way to improve strength, as described by the Hall-Petch relationship.
..... Click the link for more information.
Silicon (IPA: /ˈsɪlɪkən/ or /ˈsɪlɪˌkɑn/, Latin: silicium
..... Click the link for more information.
Semiconductor device fabrication is the process used to create chips, the integrated circuits that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photographic and chemical processing steps during which electronic circuits are
..... Click the link for more information.
quantum mechanics is the study of the relationship between energy quanta (radiation) and matter, in particular that between valence shell electrons and photons. Quantum mechanics is a fundamental branch of physics with wide applications in both experimental and theoretical physics.
..... Click the link for more information.
Microprocessor

Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging
Date Invented: Late 1960s/Early 1970s (see article for explanation)

Connects to:
..... Click the link for more information.
The field-effect transistor (FET) is a type of transistor that relies on an electric field to control the shape and hence the conductivity of a 'channel' in a semiconductor material.
..... Click the link for more information.
boule is a term used to describe a single-crystal ingot produced by synthetic means. This is the first of many steps to create an integrated circuit, as used by many today.
..... Click the link for more information.
A seed crystal is a small piece of single crystal material from which a large crystal of, usually, the same material is to be grown. 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
..... Click the link for more information.
The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors (e.g. silicon, germanium and gallium arsenide), metals (e.g. palladium, platinum, silver, gold), salts and some man made, (or "lab") gemstones.
..... Click the link for more information.
The Bridgman technique is a method of growing single crystal ingots or boules.

The method involves heating polycrystalline material in a container above its melting point and slowly cooling it from one end where a seed crystal is located.
..... Click the link for more information.
Thin-film deposition is any technique for depositing a thin film of material onto a substrate or onto previously deposited layers. "Thin" is a relative term, but most deposition techniques allow layer thickness to be controlled within a few tens of nanometers, and some (molecular
..... Click the link for more information.
Epitaxy is a kind of interface between a thin film and a substrate. The term epitaxy (Greek; epi "above" and taxis "in ordered manner") describes an ordered crystalline growth on a monocrystalline substrate.
..... Click the link for more information.
Silicon (IPA: /ˈsɪlɪkən/ or /ˈsɪlɪˌkɑn/, Latin: silicium
..... Click the link for more information.
A semiconductor is a solid that has electrical conductivity in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically.[1] Semiconductors are tremendously important in technology.
..... Click the link for more information.
integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a
..... Click the link for more information.
Sapphire is the blue variety of the mineral corundum, an aluminium oxide (Al2O3). It can be found naturally or manufactured in large crystal boules for varied applications, including infrared optical components, watch faces, high-durability windows, and wafers
..... Click the link for more information.
laser is a mechanical device that produces coherent radiation. The term "laser" is an acronym: Light Amplification by Stimulated Emission of Radiation.
..... Click the link for more information.
Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization P responds nonlinearly to the electric field E of the light.
..... Click the link for more information.
Fluorite (also called fluorspar) is a mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon.
..... Click the link for more information.


This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus


page counter