Bridgman Growth of Large SrI2:Eu2+ Single Crystals: A High-performance Scintillator for Radiation Detection Applications

Journal Article · Mon Dec 31 23:00:00 EST 2012 · Journal of Crystal Growth

DOI:https://doi.org/10.1016/j.jcrysgro.2013.01.035· OSTI ID:1089231

Boatner, Lynn A ^[1]; Ramey, Joanne Oxendine ^[1]; Kolopus, James A ^[1]; Hawrami, Rastgo ^[2]; Higgins, William ^[2]; Van Loef, Edgar ^[2]; Glodo, J. ^[2]; Shah, Kanai ^[2]; Bhattacharya, P. ^[3]; Tupitsyn, E ^[3]; Groza, Michael ^[3]; Burger, Arnold ^[3]

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1. ORNL
2. Radiation Monitoring Devices, Watertown, MA
3. Fisk University, Nashville, TN

Single-crystal strontium iodide (SrI2) doped with relatively high levels (e.g., 3 - 6 %) of Eu2+ exhibits characteristics that make this material superior, in a number of respects, to other scintillators that are currently used for radiation detection. Specifically, SrI2:Eu2+ has a light yield that is significantly higher than LaBr3:Ce3+ -a currently employed commercial high-performance scintillator. Additionally, SrI2:Eu2+ is characterized by an energy resolution as high as 2.6% at the 137Cs gamma-ray energy of 662 keV, and there is no radioactive component in SrI2:Eu2+ - unlike LaBr3:Ce3+ that contains 138La. The Ce3+-doped LaBr3 decay time is, however, faster (30 nsec) than the 1.2 sec decay time of SrI2:Eu2+. Due to the relatively low melting point of strontium iodide (~515 oC), crystal growth can be carried out in quartz crucibles by the vertical Bridgman technique. Materials-processing and crystal-growth techniques that are specific to the Bridgman growth of europium-doped strontium iodide scintillators are described here. These techniques include the use of a porous quartz frit to physically filter the molten salt from a quartz antechamber into the Bridgman growth crucible and the use of a bent or bulb grain selector design to suppress multiple grain growth. Single crystals of SrI2:Eu2+ scintillators with good optical quality and scintillation characteristics have been grown in sizes up to 5.0 cm in diameter by applying these techniques. Other aspects of the SrI2:Eu2+ crystal-growth methods and of the still unresolved crystal-growth issues are described here.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: ORNL work for others
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1089231
• Journal Information: Journal of Crystal Growth, Journal Name: Journal of Crystal Growth Vol. 379; ISSN 0022-0248
• Country of Publication: United States
• Language: English