TY - JOUR
T1 - Quaternary Iodide K(Ca,Sr)I3:Eu2+ Single-Crystal Scintillators for Radiation Detection
T2 - Crystal Structure, Electronic Structure, and Optical and Scintillation Properties
AU - Wu, Yuntao
AU - Li, Qi
AU - Chakoumakos, Bryan C.
AU - Zhuravleva, Mariya
AU - Lindsey, Adam C.
AU - Johnson, Jesse Ashby
AU - Stand, Luis
AU - Koschan, Merry
AU - Melcher, Charles L.
N1 - Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2016/10/1
Y1 - 2016/10/1
N2 - A mixed crystal strategy is reported as an effective approach to improving the performances of inorganic scintillators for radiation detection applications. The aim of this work is to optimize ternary iodide KCaI3:Eu2+ single crystals via partial Sr2+ substitution, and to provide physical insights and a strategy of designing promising halide scintillators. The ∅22 mm × 50 mm long K(Ca,Sr)I3:Eu2+ single crystals are grown by the Bridgman method. Crystal structure refinements verify the phase purity and the orthorhombic crystal system with a space group of Cmcm (No. 63) in the solid solutions. An energy resolution of 2.5 ± 0.1% at 662 keV and a light yield of 74 000 ± 4000 photons per MeV can be achieved for a 4 mm cube KCa0.835Sr0.165I3:Eu2+. It is for the first time that a halide solid solution is synthesized with a competitive scintillating performance as current state-of-the-art scintillators, such as SrI2:Eu2+ and LaBr3:Ce3+. A combination of first-principles calculations and optical characterization experiments is employed to construct the host material band edges and the relative positions of 5d and 4f energy levels of the Eu2+ activation center. The origins of the improvement of light yield and scintillation response nonproportionality are proposed from experimental and theoretical insights.
AB - A mixed crystal strategy is reported as an effective approach to improving the performances of inorganic scintillators for radiation detection applications. The aim of this work is to optimize ternary iodide KCaI3:Eu2+ single crystals via partial Sr2+ substitution, and to provide physical insights and a strategy of designing promising halide scintillators. The ∅22 mm × 50 mm long K(Ca,Sr)I3:Eu2+ single crystals are grown by the Bridgman method. Crystal structure refinements verify the phase purity and the orthorhombic crystal system with a space group of Cmcm (No. 63) in the solid solutions. An energy resolution of 2.5 ± 0.1% at 662 keV and a light yield of 74 000 ± 4000 photons per MeV can be achieved for a 4 mm cube KCa0.835Sr0.165I3:Eu2+. It is for the first time that a halide solid solution is synthesized with a competitive scintillating performance as current state-of-the-art scintillators, such as SrI2:Eu2+ and LaBr3:Ce3+. A combination of first-principles calculations and optical characterization experiments is employed to construct the host material band edges and the relative positions of 5d and 4f energy levels of the Eu2+ activation center. The origins of the improvement of light yield and scintillation response nonproportionality are proposed from experimental and theoretical insights.
KW - alkali earth halides
KW - electron traps
KW - electronic structures
KW - mixed crystals
KW - scintillators
UR - http://www.scopus.com/inward/record.url?scp=84973644279&partnerID=8YFLogxK
U2 - 10.1002/adom.201600239
DO - 10.1002/adom.201600239
M3 - Article
AN - SCOPUS:84973644279
SN - 2195-1071
VL - 4
SP - 1518
EP - 1532
JO - Advanced Optical Materials
JF - Advanced Optical Materials
IS - 10
ER -