Defect Engineering in SrI₂:Eu²⁺ Single Crystal Scintillators

Journal Article · Tue Jun 23 00:00:00 EDT 2015 · Crystal Growth and Design

DOI:https://doi.org/10.1021/acs.cgd.5b00552· OSTI ID:1265461

Wu, Yuntao ^[1]; Boatner, Lynn A. ^[2]; Lindsey, Adam C. ^[1]; Zhuravleva, Mariya ^[1]; Jones, Steven ^[3]; Auxier, John D. ^[3]; Hall, Howard L. ^[3]; Melcher, Charles L. ^[1]

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1. Univ. of Tennessee, Knoxville, TN (United States). Scintillation Materials Research Center, Dept. of Materials Science and Engineering
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Radiation Detection Materials and Systems (CRDMS)
3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering

Eu²⁺-activated strontium iodide is an excellent single crystal scintillator used for gamma-ray detection and significant effort is currently focused on the development of large-scale crystal growth techniques. A new approach of molten-salt pumping or so-called melt aging was recently applied to optimize the crystal quality and scintillation performance. Nevertheless, a detailed understanding of the underlying mechanism of this technique is still lacking. The main purpose of this paper is to conduct an in-depth study of the interplay between microstructure, trap centers and scintillation efficiency after melt aging treatment. Three SrI²:2 mol% Eu2+ single crystals with 16 mm diameter were grown using the Bridgman method under identical growth conditions with the exception of the melt aging time (e.g. 0, 24 and 72 hours). Using energy-dispersive X-ray spectroscopy, it is found that the matrix composition of the finished crystal after melt aging treatment approaches the stoichiometric composition. The mechanism responsible for the formation of secondary phase inclusions in melt-aged SrI²:Eu²⁺ is discussed. Simultaneous improvement in light yield, energy resolution, scintillation decay-time and afterglow is achieved in melt-aged SrI²:Eu²⁺. The correlation between performance improvement and defect structure is addressed. The results of this paper lead to a better understanding of the effects of defect engineering in control and optimization of metal halide scintillators using the melt aging technique.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1265461
• Journal Information: Crystal Growth and Design, Vol. 15, Issue 8; ISSN 1528-7483
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Crystal Growth
Optical Materials
Scintillation
Microstructure
Traps.