Micro-pulling-down
Encyclopedia

Basics

The micro-pulling-down (µ-PD) method is a crystal growth
Crystal growth
A crystal is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. Crystal growth is a major stage of a crystallization process, and consists in the addition of new atoms, ions, or polymer strings into...

 technique based on continuous transport of the melted substance through micro-channel(s) made in a crucible
Crucible
A crucible is a container used for metal, glass, and pigment production as well as a number of modern laboratory processes, which can withstand temperatures high enough to melt or otherwise alter its contents...

 bottom. Continuous solidification of the melt is progressed on a liquid/solid interface positioned under the crucible. In a steady state, both the melt and the crystal are pulled-down with a constant (but generally different) velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...

.

Many different types of crystal are grown by this technique, including Y3Al5O12
Yttrium aluminium garnet
Yttrium aluminium garnet is a synthetic crystalline material of the garnet group. It is also one of three phases of the yttria-aluminium composite, the other two being yttrium aluminium monoclinic and yttrium aluminium perovskite . YAG is commonly used as a host material in various solid-state...

, Si
Si
Si, si, or SI may refer to :- Measurement, mathematics and science :* International System of Units , the modern international standard version of the metric system...

, Si-Ge, LiNbO3
Lithium niobate
Lithium niobate is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, optical modulators and various other linear and non-linear optical applications.-Properties:...

,
α-Al2O3
Sapphire
Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide , when it is a color other than red or dark pink; in which case the gem would instead be called a ruby, considered to be a different gemstone. Trace amounts of other elements such as iron, titanium, or chromium can give...

, Y2O3, Sc2O3
Scandium(III) oxide
Scandium oxide, Sc2O3, scandia is a high melting white solid used in high-temperature systems , electronic ceramics, and glass composition .-Physical and chemical properties:...

,
LiF
Lithium fluoride
Lithium fluoride is an inorganic compound with the formula LiF. It is the lithium salt of hydrofluoric acid. This white solid is a simple ionic compound. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. It is mainly used as a component of molten...

, CaF2
Calcium fluoride
Calcium fluoride is the inorganic compound with the formula CaF2. This ionic compound of calcium and fluorine occurs naturally as the mineral fluorite . It is the source of most of the world's fluorine. This insoluble solid adopts a cubic structure wherein calcium is coordinated to eight fluoride...

, BaF2
Barium fluoride
Barium fluoride is a chemical compound of barium and fluorine. It is a solid which can be a transparent crystal. It occurs in nature as the mineral frankdicksonite.-Structure:...

, etc.

Crystal growth routine

Standard routine procedure used in the growth of most of µ-PD crystals is well developed. The general stages of the growths include:

- charging of the crucible with starting materials (mixture of powders),

- heating of the crucible until starting materials in the crucible are completely melted,

- upward displacement of the seed until its contact with the meniscus or crucible,

- formation of the meniscus and partial melting of the seed top,

- correction of the shape of the meniscus through appropriate adjustment of crucible temperature and position of the seed crystal,

- crystal growth through puling of the seed in downward direction,

- separation of the as grown crystal from the meniscus,

- and cooling of the system (including the crystal and the crucible) to room temperature

See also

  • Crystal growth
    Crystal growth
    A crystal is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. Crystal growth is a major stage of a crystallization process, and consists in the addition of new atoms, ions, or polymer strings into...

  • Czochralski process
    Czochralski process
    The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors , metals , salts, and synthetic gemstones...

     (Crystal Growth)
  • Float-zone silicon
    Float-zone silicon
    Float-zone silicon is very pure silicon obtained by vertical zone melting. The process was developed at Bell Labs by Henry Theuerer in 1955 as a modification of a method developed by William Gardner Pfann for germanium. In the vertical configuration molten silicon has sufficient surface tension to...

     (Crystal Growth)
  • Verneuil process
    Verneuil process
    The Verneuil process, also called flame fusion, was the first commercially successful method of manufacturing synthetic gemstones, developed in 1902 by the French chemist Auguste Verneuil. It is primarily used to produce the ruby and sapphire varieties of corundum, as well as the diamond simulants...

     (Crystal Growth)
  • Laser-heated pedestal growth
    Laser-heated pedestal growth
    Laser-heated pedestal growth is a crystal growth technique. The technique can be viewed as a miniature floating zone, where the heat source is replaced by a powerful CO2 or YAG laser...

     (Crystal Growth)
  • Flux method
    Flux method
    Flux method is a method of crystal growth where the components of the desired substance are dissolved in a solvent . The method is particularly suitable for crystals needing to be free from thermal strain and it takes place in a crucible made of non-reactive metal such as platinum, tantalum,...

     (Crystal Growth)
  • Yttrium aluminium garnet
    Yttrium aluminium garnet
    Yttrium aluminium garnet is a synthetic crystalline material of the garnet group. It is also one of three phases of the yttria-aluminium composite, the other two being yttrium aluminium monoclinic and yttrium aluminium perovskite . YAG is commonly used as a host material in various solid-state...

  • Scandium(III) oxide
    Scandium(III) oxide
    Scandium oxide, Sc2O3, scandia is a high melting white solid used in high-temperature systems , electronic ceramics, and glass composition .-Physical and chemical properties:...

  • Sapphire
    Sapphire
    Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide , when it is a color other than red or dark pink; in which case the gem would instead be called a ruby, considered to be a different gemstone. Trace amounts of other elements such as iron, titanium, or chromium can give...

  • Lithium niobate
    Lithium niobate
    Lithium niobate is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, optical modulators and various other linear and non-linear optical applications.-Properties:...


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