Gadolinium gallium garnet
Gadolinium Gallium Garnet (GGG, Gd3Ga5O12) is a synthetic crystalline material of the garnet group, with good mechanical, thermal, and optical properties. It is typically colorless. It has a cubic lattice, a density of 7.08 g/cm3 and its Mohs hardness is variously noted as 6.5 and 7.5. Its crystals are produced with the Czochralski method. During production, various dopants can be added for colour modification. The material is also used in fabrication of various optical components and as a substrate material for magneto–optical films (magnetic bubble memory).[2] It also finds use in jewelry as a diamond simulant. GGG can also be used as a seed substrate for the growth of other garnets such as yttrium iron garnet.[3]
| Gadolinium Gallium Garnet | |
|---|---|
| General | |
| Category | synthetic mineral |
| Formula (repeating unit) | Gd3Ga5O12[1] |
| Crystal system | cubic |
| Identification | |
| Color | transparent, colorless to light brown or yellow. May also be orange or blue.[1] |
| Mohs scale hardness | 6.5[1] (other sources 7.5) |
| Luster | vitreous to subadamantine[1] |
| Specific gravity | 7.05 (+.04, -.10)[1] |
| Density | 7.08 g/cm3 |
| Polish luster | vitreous to subadamantine[1] |
| Optical properties | Single refractive[1] |
| Refractive index | 1.970 (+.060)[1] |
| Birefringence | none[1] |
| Pleochroism | none[1] |
| Dispersion | .045[1] |
| Ultraviolet fluorescence | moderate to strong pinkish orange in shortwave[1] |
References
- (Gia), Gemological. Gem Reference Guide. City: Gemological Institute of America (GIA), 1988. ISBN 0-87311-019-6
- J. F. Greber "Gallium and Gallium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH, Weinheim. doi:10.1002/14356007.a12_163
- Holm, U.; Sohlstrom, H.; Brogardh, T. (1984). Kersten, Ralf T; Kist, Rainer (eds.). Yig-Sensor Design For Fibre Optical Magnetic Field Measurements. 2nd Intl Conf on Optical Fiber Sensors: OFS'84. Vol. 514. Proc. SPIE 0514, 2nd Intl Conf on Optical Fiber Sensors: OFS'84. pp. 333–6. doi:10.1117/12.945109. S2CID 107371333.
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