Lanthanum(III) bromide

Lanthanum(III) bromide
Names
	IUPAC names Lanthanum(III) bromide; Lanthanum tribromide
Identifiers
CAS Number	13536-79-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	75393 ;
ECHA InfoCard	100.033.527
EC Number	36-896-7;
PubChem CID	83563;
CompTox Dashboard (EPA)	DTXSID9065526 ;
	InChI InChI=1S/3BrH.La/h31H;/q;;;+3/p-3 Key: XKUYOJZZLGFZTC-UHFFFAOYSA-K ; InChI=1/3BrH.La/h31H;/q;;;+3/p-3 Key: XKUYOJZZLGFZTC-DFZHHIFOAJ;
	SMILES Br[La](Br)Br;
Properties
Chemical formula	LaBr3
Molar mass	378.62 g/mol (anhydrous)
Appearance	white solid, hygroscopic
Density	5.06 g/cm3, solid
Melting point	783 °C (1,441 °F; 1,056 K)
Boiling point	1,577 °C (2,871 °F; 1,850 K)
Solubility in water	Very soluble
Structure
Crystal structure	hexagonal (UCl3 type), hP8
Space group	P63/m, No. 176
Coordination geometry	Tricapped trigonal prismatic; (nine-coordinate)
Hazards
EU classification (DSD) (outdated)	not listed
Flash point	not flammable
Related compounds
Other anions	Lanthanum(III) fluoride; Lanthanum(III) chloride; Lanthanum(III) iodide
Other cations	Cerium(III) bromide; Praseodymium(III) bromide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Lanthanum(III) bromide (LaBr₃) is an inorganic halide salt of lanthanum. When pure, it is a colorless white powder. The single crystals of LaBr₃ are hexagonal crystals with melting point of 783 °C. It is highly hygroscopic and water-soluble. There are several hydrates, La₃Br·x H₂O, of the salt also known. It is often used as a source of lanthanum in chemical synthesis and as a scintillation material in certain applications.

Lanthanum bromide scintillation detector

The scintillator material cerium activated lanthanum bromide (LaBr₃:Ce) was first produced in 2001.[1] LaBr₃:Ce-based radiation detectors offer improved energy resolution, fast emission and excellent temperature and linearity characteristics. Typical energy resolution at 662 keV is 3% as compared to sodium iodide detectors at 7%.[2] The improved resolution is due to a photoelectron yield that is 160% greater than is achieved with sodium iodide. Another advantage of LaBr₃:Ce is the nearly flat photo emission over a 70 °C temperature range (~1% change in light output).

Today LaBr₃ detectors are offered with bialkali photomultiplier tubes (PMT) that can be two inches in diameter and 10 or more inches long . However, miniature packaging can be obtained by the use of a silicon drift detector (SDD) or a Silicon Photomultiplier (SiPM).[3] These UV enhanced diodes provide excellent wavelength matching to the 380 nm emission of LaBr₃. The SDD is not as sensitive to temperature and bias drift as PMT. The reported spectroscopy performance of the SDD configuration resulted in a 2.8% energy resolution at 662 keV for the detector sizes considered.

LaBr₃ introduces an enhanced set of capabilities to a range of gamma spectroscopy radioisotope detection and identification systems used in the homeland security market. Isotope identification utilizes several techniques (known as algorithms) which rely on the detector's ability to discriminate peaks. The improvements in resolution allow more accurate peak discrimination in ranges where isotopes often have many overlapping peaks. This leads to better isotope classification. Screening of all types (pedestrians, cargo, conveyor belts, shipping containers, vehicles, etc.) often requires accurate isotopic identification to differentiate concerning materials from non-concerning materials (medical isotopes in patients, naturally occurring radioactive materials, etc.) Heavy R&D and deployment of instruments utilizing LaBr₃ is expected in the upcoming years.

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References

Van Loef, E. V. D; Dorenbos, P; Van Eijk, C. W. E; Krämer, K; Güdel, H. U (2001). "High-energy-resolution scintillator: Ce3+ activated LaBr3". Applied Physics Letters. 79 (10): 1573–1575. doi:10.1063/1.1385342.
Knoll, Glenn F., Radiation Detection and Measurement 3rd ed. (Wiley, New York, 2000).
A. Dawood Butt et al., "Comparison of SiPM and SDD based readouts of 1″ LaBr3:Ce scintillator for nuclear physics applications," 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), San Diego, CA, 2015, pp. 1-4. doi: 10.1109/NSSMIC.2015.7581734

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[1] Van Loef, E. V. D; Dorenbos, P; Van Eijk, C. W. E; Krämer, K; Güdel, H. U (2001). "High-energy-resolution scintillator: Ce3+ activated LaBr3". Applied Physics Letters. 79 (10): 1573–1575. doi:10.1063/1.1385342.

[2] Knoll, Glenn F., Radiation Detection and Measurement 3rd ed. (Wiley, New York, 2000).

[3] A. Dawood Butt et al., "Comparison of SiPM and SDD based readouts of 1″ LaBr3:Ce scintillator for nuclear physics applications," 2015 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), San Diego, CA, 2015, pp. 1-4. doi: 10.1109/NSSMIC.2015.7581734