Investigating new activators for small-bandgap LaX3 (X = Br, I) scintillators

• Published in: Journal of crystal growth 2018-02, Vol.483 (C), p.251-257
• Main Authors: Rutstrom, Daniel, Collette, Robyn, Stand, Luis, Loyd, Matthew, Wu, Yuntao, Koschan, Merry, Melcher, Charles L., Zhuravleva, Mariya
• Format: Article
• Language: English
• Subjects: A1. Characterization; A2. Bridgman technique; A2. Growth from melt; B1. Halides; B1. Rare earth compounds; B3. Scintillators; MATERIALS SCIENCE
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2017.12.015

•Bi3+, Sb3+, and Eu2+ were evaluated as activators for LaI3 and LaBr3.•Eu2+ was further evaluated as an activator for LaBr3−xIx.•Single crystals were grown using the vertical Bridgman method.•Europium was successfully incorporated into all compositions in its divalent state.•Room-temperature scintillation properties are reported for doped LaI3 for the first time. Luminescence and scintillation properties of Bi3+, Sb3+, and Eu2+-doped LaI3 and LaBr3 were explored. Out of the three dopants investigated, Eu2+ was the most promising new activator for small-bandgap LaX3 (X = Br, I) and was further studied in the mixed-halide LaBr3−xIx. Crystals were grown from the melt using the vertical Bridgman method. LaBr3:Eu2+ 0.5% (mol) had the most favorable scintillation properties with a light output of 43,000 ph/MeV and 6% energy resolution at 662 keV. Performance of LaBr3−xIx:Eu2+ worsened for most samples as iodide concentration was increased. Room-temperature scintillation of LaI3:Eu2+ 0.1% and 0.5% was observed and is the first case of room-temperature emission reported for doped LaI3.