Yttrium aluminum garnet

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Yttrium aluminum garnet
Yag-rod.jpg
Yttrium-aluminum-garnet rod ( Nd - doped )
General and classification
chemical formula
  • Y 3 Al 2 [AlO 4 ] 3
  • Y 3 Al 5 O 12
Mineral class
(and possibly department)
none, as synthesis is not recognized as a mineral
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Ia 3 dTemplate: room group / 230
Lattice parameters a  = 12.00  Å
Formula units Z  = 8
Physical Properties
Mohs hardness 8 to 8.5
Density (g / cm 3 ) 4.55 to 4.65
Cleavage no
Break ; Tenacity shell-like
colour colorless, green, yellow, blue, red, purple
Line color White
transparency transparent
shine Glass gloss
Crystal optics
Refractive indices n ω  = 1.833
n ε  = 1.833
Birefringence no
Axis angle 2V = 0.028 (BG)

Yttrium - aluminum - garnet (abbreviated YAG is) an artificially-prepared crystalline compound having the chemical composition Y 3 Al 5 O 12 . An artificial crystal with a similar structure is the yttrium iron garnet (YIG, for English yttrium iron garnet ).

properties

YAG has very high acoustic wave velocities, which differ only slightly in their different spatial directions. The longitudinal wave speed in the [001] direction is 8563 m / s and for the transverse wave speed in the [001] direction is 5029.3 m / s. The isotropy factor is 1.03.

Manufacturing

YAG is produced almost exclusively using the Czochralski process (Cz process), with which single crystals of more than 300 mm in length and up to 100 mm in diameter can be grown.

use

Laser and LED

YAG is mainly used as a single-crystalline host crystal for solid-state lasers . For this purpose, it is doped with various lanthanides depending on the desired properties, especially the wavelength to be emitted , including neodymium ( Nd: YAG laser ) and erbium ( Er: YAG laser ).

For the production of white LEDs , YAG powder doped with cerium (YAG: Ce 3+ ) can be used as a yellow phosphor in combination with a blue LED ( indium gallium nitride InGaN). YAG: Ce 3+ single crystals are still used as scintillators in scanning electron microscopes (SEM), where they are used to generate particularly low-noise images.

Gemstone

YAG ( gemologically correct: granatoid ) is also a popular gemstone due to its Mohs hardness of 8 to 8.5 and its high dispersion and refractive index (together they make up the so-called fire) . Colorless and under the trade names simulated diamond (also Diamonair or Cirolit ), it served as a diamond substitute until it was replaced by the more suitable zirconia . Depending on the doping with different elements and the resulting colors green, yellow, blue, red and purple, it can also be used to imitate other gemstones.

Web links

Wiktionary: YAG  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ A b c Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X .
  2. ^ A b Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 270 .
  3. ^ A b Properties and Breeding of YAG. In: yag.de. Retrieved April 20, 2018 .
  4. a b c Gemstone etiquette from Prof. Leopold Rössler. YAG (yttrium aluminum garnet). In: beyars.com. BeyArs GmbH, accessed April 20, 2018 .
  5. ^ A b Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 275 .
  6. EG Spencer, RT Denton, TB Bateman, WB Snow, LG Van Uitert: Microwave Elastic Properties of Nonmagnetic Garnets . In: Journal of Applied Physics . tape 34 , 1963, pp. 3059-3060 , doi : 10.1063 / 1.1729120 .