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Title: Scintillation properties and increased vacancy formation in cerium and calcium co-doped yttrium aluminum garnet

Abstract

Co-doping with divalent elements is known to improve the light yield and decay times of some cerium-activated scintillators, despite the stabilization of tetravalent Ce 4+, previously believed to be non-luminescent, from the Ce 3+ state. Ce 4+ stabilization is a charge compensation mechanism which results from divalent ion substitution of a 3+site. To elucidate the underlying mechanisms, which remain poorly understood, we have grown three Ce,Ca:YAG crystals with different amounts of calcium co-dopants by the Czochralski method and characterized their scintillation and defect properties. Calcium co-doping reduces the decay times and stabilizes the formation of Ce 4+ as expected. Interestingly, X-ray fluorescence analysis reveals a decreased concentration of cerium within the YAG crystal for the sample doped with high levels of Ca, which could contribute to the observation that scintillator properties are improved only for low levels of Ca co-doping. Additionally, positron annihilation spectroscopy reveals an increase in the concentration of vacancies with increasing Ca concentration, while thermoluminescence is observed to show no detectable signal. Furthermore, room temperature photoluminescence of the Ce 4f to 5d 1 transition demonstrates decreased emission with increasing Ca co-doping. These data suggest that Ca co-doping decreases the decay time by creating defects with non-radiative decaymore » pathways.« less

Authors:
ORCiD logo [1];  [1];  [2];  [1]
  1. Washington State Univ., Pullman, WA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1544510
Report Number(s):
LLNL-JRNL-776837
Journal ID: ISSN 0022-0248; 969839
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Crystal Growth
Additional Journal Information:
Journal Volume: 507; Journal Issue: C; Journal ID: ISSN 0022-0248
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY

Citation Formats

Dickens, Peter T., Haven, Drew T., Friedrich, Stephan, and Lynn, Kelvin G. Scintillation properties and increased vacancy formation in cerium and calcium co-doped yttrium aluminum garnet. United States: N. p., 2018. Web. doi:10.1016/j.jcrysgro.2018.10.059.
Dickens, Peter T., Haven, Drew T., Friedrich, Stephan, & Lynn, Kelvin G. Scintillation properties and increased vacancy formation in cerium and calcium co-doped yttrium aluminum garnet. United States. doi:10.1016/j.jcrysgro.2018.10.059.
Dickens, Peter T., Haven, Drew T., Friedrich, Stephan, and Lynn, Kelvin G. Tue . "Scintillation properties and increased vacancy formation in cerium and calcium co-doped yttrium aluminum garnet". United States. doi:10.1016/j.jcrysgro.2018.10.059. https://www.osti.gov/servlets/purl/1544510.
@article{osti_1544510,
title = {Scintillation properties and increased vacancy formation in cerium and calcium co-doped yttrium aluminum garnet},
author = {Dickens, Peter T. and Haven, Drew T. and Friedrich, Stephan and Lynn, Kelvin G.},
abstractNote = {Co-doping with divalent elements is known to improve the light yield and decay times of some cerium-activated scintillators, despite the stabilization of tetravalent Ce4+, previously believed to be non-luminescent, from the Ce3+ state. Ce4+ stabilization is a charge compensation mechanism which results from divalent ion substitution of a 3+site. To elucidate the underlying mechanisms, which remain poorly understood, we have grown three Ce,Ca:YAG crystals with different amounts of calcium co-dopants by the Czochralski method and characterized their scintillation and defect properties. Calcium co-doping reduces the decay times and stabilizes the formation of Ce4+ as expected. Interestingly, X-ray fluorescence analysis reveals a decreased concentration of cerium within the YAG crystal for the sample doped with high levels of Ca, which could contribute to the observation that scintillator properties are improved only for low levels of Ca co-doping. Additionally, positron annihilation spectroscopy reveals an increase in the concentration of vacancies with increasing Ca concentration, while thermoluminescence is observed to show no detectable signal. Furthermore, room temperature photoluminescence of the Ce 4f to 5d1 transition demonstrates decreased emission with increasing Ca co-doping. These data suggest that Ca co-doping decreases the decay time by creating defects with non-radiative decay pathways.},
doi = {10.1016/j.jcrysgro.2018.10.059},
journal = {Journal of Crystal Growth},
number = C,
volume = 507,
place = {United States},
year = {2018},
month = {10}
}

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