Defect Engineering by Codoping in KCaI3:Eu2+ Single-Crystalline Scintillators

作     者：Yuntao Wu Qi Li Steven Jones Chaochao Dun Sheng Hu Mariya Zhuravleva Adam C. Lindsey Luis Stand Matthew Loyd Merry Koschan John Auxier, II Howard L. Hall Charles L. Melcher 

作者机构：Scintillation Materials Research Center University of Tennessee Knoxville Tennessee 37996 USA Department of Materials Science and Engineering University of Tennessee Knoxville Tennessee 37996 USA Physical Science Division IBM Thomas J Watson Research Center Yorktown Heights New York 10598 USA Department of Computer Science University of Illinois at Urbana-Champaign Urbana Illinois 61801 USA Department of Nuclear Engineering University of Tennessee Knoxville Tennessee 37996 USA Department of Physics Wake Forest University Winston-Salem North Carolina 27109 USA Department of Chemical and Biomolecular Engineering University of Tennessee Knoxville Tennessee 37996 USA 

出 版 物：《Physical Review Applied》 (Phys. Rev. Appl.)

年 卷 期：2017年第8卷第3期

页      面：034011-034011页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：U.S. Department of Homeland Security, DHS Domestic Nuclear Detection Office, DNDO, (2012-DN-077-ARI067-06) Domestic Nuclear Detection Office, DNDO 

主　　题：Crystal defects Crystal growth Dopants Luminescence Point defects Solid-state detectors Medical imaging Scintillators 

摘      要：Eu2+-doped alkali or alkali earth iodide scintillators with energy resolutions ≤3% at 662 keV promise the excellent discrimination ability for radioactive isotopes required for homeland-security and nuclear-nonproliferation applications. To extend their applications to x-ray imaging, such as computed tomography scans, the intense afterglow which delays the response time of such materials is an obstacle that needs to be overcome. However, a clear understanding of the origin of the afterglow and feasible solutions is still lacking. In this work, we present a combined experimental and theoretical investigation of the physical insights of codoping-based defect engineering which can reduce the afterglow effectively in KCaI3:Eu2+ single-crystal scintillators. We illustrate that Sc3+ codoping greatly suppresses the afterglow, whereas Y3+, Gd3+, or La3+ codoping enhances the afterglow. Meanwhile, a light yield of 57 000 photons/MeV and an energy resolution of 3.4% at 662 keV can be maintained with the appropriate concentration of Sc3+ codoping, which makes the material promising for medical-imaging applications. Through our thermoluminescence techniques and density-functional-theory calculations, we are able to identify the defect structures and understand the mechanism by which codoping affects the scintillation performance of KCaI3:Eu2+ crystals. The proposed defect-engineering strategy is further validated by achieving afterglow suppression in Mg2+ codoped KCaI3:Eu2+ single crystals.