Lutetium oxyorthosilicate
Crystal structure | |||||||||||||
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__ Lu 3+ __ Si 4+ __ O 2− | |||||||||||||
General | |||||||||||||
Surname | Lutetium oxyorthosilicate | ||||||||||||
other names |
LSO |
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Ratio formula | Lu 2 SiO 5 | ||||||||||||
Brief description |
trigonal, colorless crystals |
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External identifiers / databases | |||||||||||||
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properties | |||||||||||||
Molar mass | 458.0165 g mol −1 | ||||||||||||
Physical state |
firmly |
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density |
7.4 g cm −3 |
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Melting point |
2047 ° C |
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Refractive index |
1.82 |
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safety instructions | |||||||||||||
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As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C |
Lutetium oxyorthosilicate (LSO) is a silicon - oxygen compound of lutetium .
Doped with cerium , it is suitable as a scintillator material for the detection of gamma rays . LSO was developed in the early 1990s and has since replaced the bismuth germanate (BGO) and gadolinium orthosilicate (GSO) scintillators used in many of the positron emission tomography (PET) systems available today . The refractive index is 1.82, the linear attenuation coefficient µ is 0.87 cm −1 and the time constant for the decay of a scintillation is 40 ns. The u. a. of atomic number and cross-section dependent photoelectric effect proportion μ r case of photon energy of 511 keV is 34%. LSO crystals have a trigonal crystal structure and a Mohs hardness of 5.8.
The very short time constant of 40 ns compared to 300 ns with BGO enables smaller coincidence windows in positron emission tomography and thus higher count rates than would otherwise be possible with the same device design. The linear attenuation coefficient µ is, however, lower than that of BGO (0.87 cm −1 vs. 0.96 cm −1 ), so that the sensitivity for gamma quanta is somewhat lower.
Lutetium oxyorthosilicate crystallizes in the monoclinic crystal system , space group C 2 / c (space group no. 15) , with the lattice parameters a = 14.28 Å , b = 6.640 Å, c = 10.25 Å and β = 122.2 °. The structure contains isolated O 2− and SiO 4 4− ions.
literature
- Guohao Ren, Laishun Qin, Huanying Li, Sheng Lu: Investigation on defects in Lu 2 SiO 5 : Ce crystals grown by Czochralski method. In: Crystal Research and Technology. Volume 41, Number 2, pp. 163-167, February 2006, doi: 10.1002 / crat.200510549
Web links
- Patent US6323489 : Single crystal scinitillator. Published November 27, 2001 , Inventor: Kenneth J. McClellan.
Individual evidence
- ↑ a b c d e MTI Corporation: New Scintillation Crystal Ce: Lu 2 SiO 5 ( MS Word ; 289 kB).
- ↑ harmonized classification for this substance . A labeling of Dilutetium oxide silicate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), retrieved on July 28, 2019, is reproduced from a self-classification by the distributor . There is not yet a
- ^ Charles L. Melcher: Scintillation Crystals for PET . In: Journal of Nuclear Medicine . tape 41 , no. 6 , 2000, ISSN 0161-5505 , p. 1051-1055 , PMID 10855634 (free full text).
- ^ A b William W. Moses: Nuclear Medical Imaging Techniques and Challenges ( Memento of January 31, 2012 in the Internet Archive ). Lawrence Berkeley National Laboratory Department of Functional Imaging, February 9, 2005 (PDF; 9.3 MB).
- ↑ T. Gustafsson, M. Klintenberg, SE Derenzo, MJ Weber, JO Thomas: Lu 2 SiO 5 by single-crystal X-ray and neutron diffraction. In: Acta Crystallographica , C57, 2001, pp. 668-669, doi: 10.1107 / S0108270101005352 .