Cerium(III) bromide explained

Cerium(III) bromide is an inorganic compound with the formula CeBr₃. This white hygroscopic solid is of interest as a component of scintillation counters.

Preparation and basic properties

The compound has been known since at least 1899, when Muthman and Stützel reported its preparation from cerium sulfide and gaseous HBr.^[1] Aqueous solutions of CeBr₃ can be prepared from the reaction of Ce₂(CO₃)₃·H₂O with HBr. The product, CeBr₃·H₂O can be dehydrated by heating with NH₄Br followed by sublimation of residual NH₄Br. CeBr₃ can be distilled at reduced pressure (~ 0.1 Pa) in a quartz ampoule at 875-880 °C.^[2] Like the related salt CeCl₃, the bromide absorbs water on exposure to moist air. The compound melts congruently at 722 °C, and well ordered single crystals may be produced using standard crystal growth methods like Bridgman or Czochralski.

CeBr₃ adopts the hexagonal, UCl₃-type crystal structure with the P6₃/m space group.^{[3] [4]} The cerium ions are 9-coordinate and adopt a tricapped trigonal prismatic geometry. The cerium–bromine bond lengths are 3.11 Å and 3.16 Å.^[5]

Applications

CeBr₃-doped lanthanum bromide single crystals are known to exhibit superior scintillation properties for applications in the security, medical imaging, and geophysics detectors.^{[6] [7]}

Undoped single crystals of CeBr₃ have shown promise as a γ-ray scintillation detector in nuclear non-proliferation testing, medical imaging, environmental remediation, and oil exploration.^[8]

Suppliers

• Sigma-Aldrich

References

1. Muthmann . W. . Stützel . L. . Eine einfache Methode zur Darstellung der Schwefel-, Chlor- und Brom-Verbindungen der Ceritmetalle . Berichte der Deutschen Chemischen Gesellschaft . Wiley . 32 . 3 . 1899 . 0365-9496 . 10.1002/cber.189903203115 . 3413–3419 . de.
2. Rycerz . L. . Ingier-Stocka . E. . Berkani . M. . Gaune-Escard . M. . Thermodynamic Functions of Congruently Melting Compounds Formed in the CeBr₃−KBr Binary System . Journal of Chemical & Engineering Data . American Chemical Society (ACS) . 52 . 4 . 2007 . 0021-9568 . 10.1021/je600517u . 1209–1212.
3. Morosin . B. . Crystal Structures of Anhydrous Rare-Earth Chlorides . The Journal of Chemical Physics . AIP Publishing . 49 . 7 . 1968 . 0021-9606 . 10.1063/1.1670543 . 3007–3012. 1968JChPh..49.3007M .
4. Book: A. F. . Wells . Structural Inorganic Chemistry . 5th . 1984 . Oxford University Press . 978-0-19-965763-6 . 421 .
5. W. H. . Zachariasen . William Houlder Zachariasen . Crystal chemical studies of the 5f-series of elements. I. New structure types . . 1 . 5 . 265–268 . 1948 . 10.1107/S0365110X48000703 . 1948AcCry...1..265Z .
6. van Loef . E. V. D. . Dorenbos . P. . van Eijk . C. W. E. . Krämer . K. . Güdel . H. U. . High-energy-resolution scintillator: Ce³⁺ activated LaBr₃ . Applied Physics Letters . AIP Publishing . 79 . 10 . 2001-09-03 . 0003-6951 . 10.1063/1.1385342 . 1573–1575. 2001ApPhL..79.1573V .
7. Menge . Peter R. . Gautier . G. . Iltis . A. . Rozsa . C. . Solovyev . V. . Performance of large lanthanum bromide scintillators . Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment . Elsevier BV . 579 . 1 . 2007 . 0168-9002 . 10.1016/j.nima.2007.04.002 . 6–10. 2007NIMPA.579....6M .
8. Higgins . W.M. . Churilov . A. . van Loef . E. . Glodo . J. . Squillante . M. . Shah . K. . Crystal growth of large diameter LaBr₃:Ce and CeBr₃ . Journal of Crystal Growth . Elsevier BV . 310 . 7–9 . 2008 . 0022-0248 . 10.1016/j.jcrysgro.2007.12.041 . 2085–2089. 2008JCrGr.310.2085H .