Structure and scintillation of Eu super(2+)-activated calcium bromide iodide

• Published in: Journal of luminescence Vol. 159; pp. 274 - 279
• Main Authors: Gundiah, Gautam, Gascon, Martin, Bizarri, Gregory, Derenzo, Stephen E, Bourret-Courchesne, Edith D
• Format: Journal Article
• Language: English
• Published: 01.03.2015
• Subjects: Anions; Atomic properties; Atomic structure; Bromides; Calcium; Decay; Density; Iodides; Scintillation
• ISSN: 0022-2313
• DOI: 10.1016/j.jlumin.2014.11.031

We report the structure and scintillation properties of Eu super(2+)-activated calcium bromide iodide. CaBr sub(0.7)I sub(1.3) was the only composition that could be synthesized in the CaBr sub(2)-CaI sub(2) system. The compound has an effective atomic number of 47 and crystallizes in a trigonal crystal system with the R-3 space group and a density of 3.93 g/cc. The structure is layered and contains Ca in an octahedral environment with the Br/I anions jointly occupying a single site. Eu super(2+)-activated samples show an intense narrow emission, characteristic of the 5d-4f transition of Eu super(2+), when excited with UV or X-rays. The sample with 0.5% Eu shows a light output of 63,000 ph/MeV at 662 keV with 96% of the light emitted with a monoexponential decay time of 1332 ns. An energy resolution of 10.4% full width at half maximum (FWHM) has been achieved for 662 keV gamma rays at room temperature.